[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
Paul Koning wrote: > Suppose you had schematics of, say, a KA-10. You could turn those > gates into VHDL or Verilog, and that should deliver an exact replica > of the original machine, bug for bug compatible. That assumes the > timing quirks are manageable The mapping from asynchronous pulses, delay lines, etc, to VHDL or Verilog isn't entirely straight forward. Still, it can be done, and in the case of a KA10, it has. See https://github.com/aap/fpdpga
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
CAREY SCHUG wrote: > What I wish somebody would create is an S-100 card (probably with a > raspberry pie daughter running simulation for future upgradeability) > that, initially emulates a complete Byte-8 or Imsai computer including > memory and disk images on sdc cards, 24x40 display on an HDMI display > and USB keyboard. serial and parallel ports emulated. I believe this tick some of your boxes: https://thehighnibble.com/imsai8080/
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
our 1620 model 2 still did multiplication by table lookup. --Carey > On 02/27/2024 9:53 PM CST Chuck Guzis via cctalk > wrote: > > > On 2/27/24 18:34, CAREY SCHUG via cctalk wrote: > > > And the 1620 does addition and multiplication by table lookup. > > That was only the CADET; the Model II had the math hardcoded. There was > an octal arithmetic option for the Model II, so it could do binary math > of a sort. Spent lots of fun hours on a CADET with a 1311 disk drive. > > --Chuck
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
On 2/27/24 18:34, CAREY SCHUG via cctalk wrote: > And the 1620 does addition and multiplication by table lookup. That was only the CADET; the Model II had the math hardcoded. There was an octal arithmetic option for the Model II, so it could do binary math of a sort. Spent lots of fun hours on a CADET with a 1311 disk drive. --Chuck
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
On 2/27/24 20:34, CAREY SCHUG via cctalk wrote: Again, even if somebody offered me a complete IBM model 30 with disk and tape drives, I could not afford the shipping. would A 360/30 could be a real problem. It used air bags to push the microcode cards against the bit line boards. Those air bags looked suspiciously like IV bags from the hospital. I can't imagine they would still hold air after 50 years. The 360/40 had mylar cards with flex-print to make the microcode word lines, these were punched to break the lines so they went either through, or around the sense transformers to select a 1 or 0 for that bit. Old mylar tends to crack, and I assume that would break the conductive printing. The 360/50 and /65 had capacitive microcode read only storage which consisted of bit line boards with copper squares and word line boards that had zig-zag word line traces that had either the drive line or balance line widened to cover the bit line square, to select 1 or 0. These boards were separated by a 1 mil mylar sheet, and squeezed by a spring-loaded metal plate and a foam pressure spreader. I think these have at least a SLIGHT chance of still working after 5 decades. The power was not real high on these machines, although the peripherals could draw a lot. The 360/50 and /65 CPUs drew just a couple KW each. Of course, the models /50 and /65 were a LOT bigger than a /30, and much heavier. There's a reason people used to talk about "big iron". As for the logic, the 360's used SLT, a 1/2" square ceramic hybrid with, generally two transistors, 4 diodes and 4 resistors per package. The complete schematics for all of them are in the FEMM, and I'll bet one could replace them with a tiny PCB with SOT23 transistors, etc. to replace any bad modules. Jon
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
I'd say the real cost is the second or third system to get spare parts. that is why I want to replace the WD chip. the microprocessor talks to it at bus speed. the os knows it has to wait, though some waits are for the wd chip to say it is done. a SIMPLE mod to the legacy OS can eliminate those waits, thus IO as fast as a real hard disk, maybe as fast as an SSD. I love the 1130, the only I/O instructions given to the printer are input. And the 1620 does addition and multiplication by table lookup. Again, even if somebody offered me a complete IBM model 30 with disk and tape drives, I could not afford the shipping. would probably have to take out the a window to get it inside (big expense), and it might instantly become a basement installation. I'd have to have much more power and A/C installed. And no spare parts. Now, any front panels... Even recreations of front panels would be treasured. In the 1980s the Bradford exchange had a 360/40 front panel mounted in their space with lights artificially flashing. I might even attempt to modify an emulator program to flash the lights appropriately. --Carey > On 02/27/2024 7:16 PM CST ben via cctalk wrote: > > > On 2024-02-27 3:09 p.m., Paul Koning via cctalk wrote: > > > > > >> On Feb 27, 2024, at 4:49 PM, CAREY SCHUG via cctalk > >> wrote: > >> > >> Religion warning: I was a mainframer. Since at any practical budget, > >> they can only be emulated, > > > > Dumpster diving is a 0 dollar budget. > People could afford the APPLE II, 8080 S-100 bus, SWTPC 6909. I assume > with careful shopping one can rebuild them for about the same price, in > small quanities. > Power supplies require harder to find parts. > > Main frame rebuilding is costly, but I suspect the real cost is I/O > that can't be duplicated. A hardware emulation using microcode to me > is real computer, a windows fly by night emulation is not, as the base > platform is too unstable. > > > > Depends on your definition of emulated. Is an FPGA version merely an > > "emulation"? You might say yes if it's a functional model. Arguably no, > > if it's a gate level model. > > > I have bad luck with FPGA's, too many timing issues with routing. > I have better luck with a 2901 4 bit alu and some support logic mounted > on a small pcb. > > > Suppose you had schematics of, say, a KA-10. You could turn those gates > > into VHDL or Verilog, and that should deliver an exact replica of the > > original machine, bug for bug compatible. That assumes the timing quirks > > are manageable, which for most machines should be true. (It isn't for a > > CDC 6600.) > > > > paul > > The IBM 1130 is also a pretty scary machine inside. > The blog is here. > https://rescue1130.blogspot.com/ > > Ben.
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
On 2024-02-27 3:09 p.m., Paul Koning via cctalk wrote: On Feb 27, 2024, at 4:49 PM, CAREY SCHUG via cctalk wrote: Religion warning: I was a mainframer. Since at any practical budget, they can only be emulated, Dumpster diving is a 0 dollar budget. People could afford the APPLE II, 8080 S-100 bus, SWTPC 6909. I assume with careful shopping one can rebuild them for about the same price, in small quanities. Power supplies require harder to find parts. Main frame rebuilding is costly, but I suspect the real cost is I/O that can't be duplicated. A hardware emulation using microcode to me is real computer, a windows fly by night emulation is not, as the base platform is too unstable. Depends on your definition of emulated. Is an FPGA version merely an "emulation"? You might say yes if it's a functional model. Arguably no, if it's a gate level model. I have bad luck with FPGA's, too many timing issues with routing. I have better luck with a 2901 4 bit alu and some support logic mounted on a small pcb. Suppose you had schematics of, say, a KA-10. You could turn those gates into VHDL or Verilog, and that should deliver an exact replica of the original machine, bug for bug compatible. That assumes the timing quirks are manageable, which for most machines should be true. (It isn't for a CDC 6600.) paul The IBM 1130 is also a pretty scary machine inside. The blog is here. https://rescue1130.blogspot.com/ Ben.
[cctalk] Re: Resurrecting old microcomputers
> On Feb 27, 2024, at 5:22 PM, CAREY SCHUG via cctalk > wrote: > > OK, probably the hardest part is the floppy disk, as the mechanics corrode > over time > more than chips. > > People have built electronics to connect to a floppy cable and emulate a drive > electronically. Difficult to catch the timing on flux changes and digitize. Not hard for floppies. Harder but still doable for MFM hard drives -- David Gesswein did a very impressive version that's surprisingly inexpensive, using a BeagleBone Black or Green as the control engine. I have one, it works perfectly. paul
[cctalk] Re: emulating floppies [was: Paper tape in casettes...]
CORRECTION: GCR was used on Apple2, 400K/800K Mac, Commodore, Sirius/Vector, etc. That should read Victor 9000, NOT Vector [Graphics] Vector Graphics was hard sectored, and not GCR. Northstar is probably the best known of the hard sector formats.
[cctalk] Re: emulating floppies [was: Paper tape in casettes...]
On Tue, 27 Feb 2024, CAREY SCHUG via cctalk wrote: did not know about gcr/mfm on same floppy...if you respond, please mention who does that. gaak, I don't even recognize "gcr" at this point. I remember mfm and something else. mfm was single density, right? was gcr double density? does not seem familiar, but certainly there was a double density encoding scheme that the device attached to the floppy cable would have to recognize. Grossly oversimplified: FM is Frequency Modulation, often called "single density". There are clock pulses, and bit or no bit between the pulses, therefore, strings of off bits look like one frewuency, and strings of on bits look like another (double) frequency. MFM is Modified Frequency modulation. when it came out, it was almost double the capacity of FM, so the marketing people called it "double density". It wasn't until after that naming that FM began to be called "single density" (In a very similar way, if you look at old newspapers, "World War 1" wasn't called that until the existence or spectre of "World War 2") It was obvious that clock pulses weren't really needed between on bits. By leaving those ones out, the average frequency/signal density was much lower, making it possible to increase (typically double) the data transfer rate. and thus almost twice the capacity per track. GCR is Group Coded Record. Some patterns of bits are more "spread out" than others. If you can find those, you could break up your 8 bit data into 2 "nybbles" of 4 bits each, using only the nybbles that were spread out enough to increase the data transfer rate, and squeeze more of those pairs into the space that the 8 bit bytes had taken. If you can find 32 "loose" patterns, then you could record 5 bytes into 8 of those patterns. A little extra firmware to do the conversion, but nothing horrendous. Thus GCR typically would be about one and a half as much data per track as FM, GCR was used on Apple2, 400K/800K Mac, Commodore, Sirius/Vector, etc. 1.4M Mac is ordinary MFM, and can be done with WD style disk controllers. Commodore Amiga was MFM, BUT, did not have the IBM/WD track and sector structures; losing those, and reading a track at a time, and decoding that into sectors in software permitted a little more capacity per track/disk. In addition, on some hard drives, RLL (Run Length limited) is similar to GCR. Changing the motor speed or the data transfer rate for different tracks, makes it easier to use different numbers of sectors, to put less data on the small inner tracks, and more on the longer outer tracks. In order to get closer to a standard linear velocity on the track, instead of a standard angular velocity. There are a few machines, such as Ensoniq, that would put multiple sizes of sectors on a track! You can fit 5 1024 byte sectors on a track, but not enough left for a sixth; however there was enough space for an additional 512 byte sector. There were more recording formats, such as MMFM, having FM sector headers, with MFM sector content, etc. The NEC 765 and its ilk are similar to WD 179x in capability, but with important differences, including, WD has a "track read" command, NEC does not but has a "multiple sector resd", NEC is "flash blinded" by the index pulse, and needs a little more time after index before reading, some NEC controllers can't handle 128 byte MFM sector, many are implemented without support for FM on the FDC board, . . . -- Grumpy Ol' Fred ci...@xenosoft.com
[cctalk] Re: emulating floppies [was: Paper tape in casettes...]
On 2/27/24 15:43, Wayne S via cctalk wrote: > I know you do this for a living and are good at it. Most of us don’t do it as > a living but have piles of floppies that we want to recover cheaply using an > existing method. Grease, cat and other wezels, are fine but you have to do > more work to get usable stuff, unless your floppies are all c64 The > applesauce just seems further along than the others. > Just my opinion. To be fair, the OP was talking about replacing the WD disk controller. As far as I know, WD 17xx and 27xx controllers can do FM and MFM. Heck, they can't even do M2FM. A small exception. Back in the 1970s, we did do GCR using the WD1781, which is basically a 1771 without the modulation appendages. And even then, it took a Multibus-sized board to implement the scheme. --Chuck
[cctalk] Re: emulating floppies [was: Paper tape in casettes...]
Vector uses gcr. Apparently. I’m not well versed in any of this, just relaying stuff i read from the Applesauce discord support channel. People ask questions like all of yours there all the time. Join it and scroll back on that channel. Lotsa interesting stuff. Sent from my iPhone > On Feb 27, 2024, at 15:43, Wayne S wrote: > > I know you do this for a living and are good at it. Most of us don’t do it > as a living but have piles of floppies that we want to recover cheaply using > an existing method. Grease, cat and other wezels, are fine but you have to > do more work to get usable stuff, unless your floppies are all c64 The > applesauce just seems further along than the others. > Just my opinion. > > Sent from my iPhone > >> On Feb 27, 2024, at 15:33, CAREY SCHUG via cctalk >> wrote: >> >> I knew most of this, which is why emulating the floppy controller should be >> easier. >> >> applesauce is platform specific (ok, ANY floppy emulation will be platform >> specific for apple) >> >> I thought the applesauce page said it was not yet available for standard >> shugart style as in trs-80, s-100... >> >> greaseweasel is platform specific. the color coco is not yet available in >> the USA, needing shipping from Europe, which in my experience is not cheap. >> not even promised for trs80 1/3/4 or s-100. and are the parts cheap? dunno. >> >> did not know about gcr/mfm on same floppy...if you respond, please mention >> who does that. gaak, I don't even >> recognize "gcr" at this point. I remember mfm and something else. mfm was >> single density, right? was gcr >> double density? does not seem familiar, but certainly there was a double >> density encoding scheme that the >> device attached to the floppy cable would have to recognize. >> >> I had forgotten that atari? commodore? changed speed, though I remember I >> knew that before. >> >> --Carey >> On 02/27/2024 5:18 PM CST Wayne S via cctalk wrote: >>> >>> >>> The “support” channel has the most info on the applesause. >>> >>> >>> Sent from my iPhone >>> On Feb 27, 2024, at 15:12, Wayne S wrote: >>> >>> Chuck, not to disagree much, because you are an expert, but there’s more >>> to decoding floppies than just reading them. Some floppies have tracks that >>> are recorded at different speeds. Some have tracks that use different >>> modulation gcr on some and mfm on others. A lot of floppies have different >>> skew. The applesauce tries to handle these problems and give you a readable >>> file. It’s mostly in the software. >>> >>> I tried to send the discord link but don’t know if it got thru so here it >>> is again >>> >>> https://discord.gg/njetE8zU >>> >>> Wayne >>> >>> >>> Sent from my iPhone >>> On Feb 27, 2024, at 15:02, Chuck Guzis via cctalk wrote: >>> >>> On 2/27/24 14:42, Wayne S via cctalk wrote: >>> Take a look at the Applesauce. >>> It hooks up to a lot of different floppy drives and records and decodes the >>> flux. >>> Version2 of the hardware is being sourced and should be available in a few >>> months. >>> >>> Good grief, there are more of these things floating around than one can >>> shake a stick at. The Greasweazel is perhaps the cheapest, using a $3 >>> ($1.30 or so from Aliexpress) STM32F103 "Blue Pill" board. >>> >>> It's almost trivial doing this if you don't need the "eye candy". >>> Basically you run a timer in capture mode, with capture triggered by an >>> edge on the drive's "read data" line. >>> >>> Modern MCUs don't even break a sweat doing this. >>> >>> It's nice seeing the proliferation after many years of harping on the >>> subject... >>> >>> --Chuck
[cctalk] Re: emulating floppies [was: Paper tape in casettes...]
I know you do this for a living and are good at it. Most of us don’t do it as a living but have piles of floppies that we want to recover cheaply using an existing method. Grease, cat and other wezels, are fine but you have to do more work to get usable stuff, unless your floppies are all c64 The applesauce just seems further along than the others. Just my opinion. Sent from my iPhone > On Feb 27, 2024, at 15:33, CAREY SCHUG via cctalk > wrote: > > I knew most of this, which is why emulating the floppy controller should be > easier. > > applesauce is platform specific (ok, ANY floppy emulation will be platform > specific for apple) > > I thought the applesauce page said it was not yet available for standard > shugart style as in trs-80, s-100... > > greaseweasel is platform specific. the color coco is not yet available in > the USA, needing shipping from Europe, which in my experience is not cheap. > not even promised for trs80 1/3/4 or s-100. and are the parts cheap? dunno. > > did not know about gcr/mfm on same floppy...if you respond, please mention > who does that. gaak, I don't even > recognize "gcr" at this point. I remember mfm and something else. mfm was > single density, right? was gcr > double density? does not seem familiar, but certainly there was a double > density encoding scheme that the > device attached to the floppy cable would have to recognize. > > I had forgotten that atari? commodore? changed speed, though I remember I > knew that before. > > --Carey > >> On 02/27/2024 5:18 PM CST Wayne S via cctalk wrote: >> >> >> The “support” channel has the most info on the applesause. >> >> >> Sent from my iPhone >> >> On Feb 27, 2024, at 15:12, Wayne S wrote: >> >> Chuck, not to disagree much, because you are an expert, but there’s more >> to decoding floppies than just reading them. Some floppies have tracks that >> are recorded at different speeds. Some have tracks that use different >> modulation gcr on some and mfm on others. A lot of floppies have different >> skew. The applesauce tries to handle these problems and give you a readable >> file. It’s mostly in the software. >> >> I tried to send the discord link but don’t know if it got thru so here it is >> again >> >> https://discord.gg/njetE8zU >> >> Wayne >> >> >> Sent from my iPhone >> >> On Feb 27, 2024, at 15:02, Chuck Guzis via cctalk >> wrote: >> >> On 2/27/24 14:42, Wayne S via cctalk wrote: >> Take a look at the Applesauce. >> It hooks up to a lot of different floppy drives and records and decodes the >> flux. >> Version2 of the hardware is being sourced and should be available in a few >> months. >> >> Good grief, there are more of these things floating around than one can >> shake a stick at. The Greasweazel is perhaps the cheapest, using a $3 >> ($1.30 or so from Aliexpress) STM32F103 "Blue Pill" board. >> >> It's almost trivial doing this if you don't need the "eye candy". >> Basically you run a timer in capture mode, with capture triggered by an >> edge on the drive's "read data" line. >> >> Modern MCUs don't even break a sweat doing this. >> >> It's nice seeing the proliferation after many years of harping on the >> subject... >> >> --Chuck
[cctalk] emulating floppies [was: Paper tape in casettes...]
I knew most of this, which is why emulating the floppy controller should be easier. applesauce is platform specific (ok, ANY floppy emulation will be platform specific for apple) I thought the applesauce page said it was not yet available for standard shugart style as in trs-80, s-100... greaseweasel is platform specific. the color coco is not yet available in the USA, needing shipping from Europe, which in my experience is not cheap. not even promised for trs80 1/3/4 or s-100. and are the parts cheap? dunno. did not know about gcr/mfm on same floppy...if you respond, please mention who does that. gaak, I don't even recognize "gcr" at this point. I remember mfm and something else. mfm was single density, right? was gcr double density? does not seem familiar, but certainly there was a double density encoding scheme that the device attached to the floppy cable would have to recognize. I had forgotten that atari? commodore? changed speed, though I remember I knew that before. --Carey > On 02/27/2024 5:18 PM CST Wayne S via cctalk wrote: > > > The “support” channel has the most info on the applesause. > > > Sent from my iPhone > > On Feb 27, 2024, at 15:12, Wayne S wrote: > > Chuck, not to disagree much, because you are an expert, but there’s more to > decoding floppies than just reading them. Some floppies have tracks that are > recorded at different speeds. Some have tracks that use different modulation > gcr on some and mfm on others. A lot of floppies have different skew. The > applesauce tries to handle these problems and give you a readable file. It’s > mostly in the software. > > I tried to send the discord link but don’t know if it got thru so here it is > again > > https://discord.gg/njetE8zU > > Wayne > > > Sent from my iPhone > > On Feb 27, 2024, at 15:02, Chuck Guzis via cctalk > wrote: > > On 2/27/24 14:42, Wayne S via cctalk wrote: > Take a look at the Applesauce. > It hooks up to a lot of different floppy drives and records and decodes the > flux. > Version2 of the hardware is being sourced and should be available in a few > months. > > Good grief, there are more of these things floating around than one can > shake a stick at. The Greasweazel is perhaps the cheapest, using a $3 > ($1.30 or so from Aliexpress) STM32F103 "Blue Pill" board. > > It's almost trivial doing this if you don't need the "eye candy". > Basically you run a timer in capture mode, with capture triggered by an > edge on the drive's "read data" line. > > Modern MCUs don't even break a sweat doing this. > > It's nice seeing the proliferation after many years of harping on the > subject... > > --Chuck
[cctalk] Re: applesauce vs western digital emulator
On 2/27/24 14:50, CAREY SCHUG via cctalk wrote: > but still only floppy speeds. maybe they have software mods for larger > capacity, but > still only floppy speeds. emulate the western digital chip and go as fast as > the > original machine can handle it. There are inexpensive floppy emulators available with custom software. Search for "Gotek". You can even modify the basic cheap unit to have a small OLED screen and a rotary encoder for switching among the hundreds of images that you've recorded using your Greaseweazle. The Gotek is essentially a cheap MCU-with some level-shifting logic and a USB port for a pen drive. There is also an emulator for an MFM hard drive. Silicon just keeps marching on... --Chuck
[cctalk] "HB A8" ISA SCSI controller BIOS image?
I have some 8-bit ISA 53c90a based SCSI controllers labeled "SCSI HB A8". Mine are made by "Advanced Information Concepts", but apparently they were also made by "Control Concepts". Unfortunately, mine don't have the BIOS chips installed. I have a picture of the card with a chip installed labeled "Ver-3.02 CCI 0991", so I know an 8k or 16k boot prom existed. Does anyone have such a card that they'd be willing to dump a prom image from (or let me borrow it to dump). KJ
[cctalk] Re: Paper tape in casettes...
The “support” channel has the most info on the applesause. Sent from my iPhone On Feb 27, 2024, at 15:12, Wayne S wrote: Chuck, not to disagree much, because you are an expert, but there’s more to decoding floppies than just reading them. Some floppies have tracks that are recorded at different speeds. Some have tracks that use different modulation gcr on some and mfm on others. A lot of floppies have different skew. The applesauce tries to handle these problems and give you a readable file. It’s mostly in the software. I tried to send the discord link but don’t know if it got thru so here it is again https://discord.gg/njetE8zU Wayne Sent from my iPhone On Feb 27, 2024, at 15:02, Chuck Guzis via cctalk wrote: On 2/27/24 14:42, Wayne S via cctalk wrote: Take a look at the Applesauce. It hooks up to a lot of different floppy drives and records and decodes the flux. Version2 of the hardware is being sourced and should be available in a few months. Good grief, there are more of these things floating around than one can shake a stick at. The Greasweazel is perhaps the cheapest, using a $3 ($1.30 or so from Aliexpress) STM32F103 "Blue Pill" board. It's almost trivial doing this if you don't need the "eye candy". Basically you run a timer in capture mode, with capture triggered by an edge on the drive's "read data" line. Modern MCUs don't even break a sweat doing this. It's nice seeing the proliferation after many years of harping on the subject... --Chuck
[cctalk] Re: Paper tape in casettes...
Chuck, not to disagree much, because you are an expert, but there’s more to decoding floppies than just reading them. Some floppies have tracks that are recorded at different speeds. Some have tracks that use different modulation gcr on some and mfm on others. A lot of floppies have different skew. The applesauce tries to handle these problems and give you a readable file. It’s mostly in the software. I tried to send the discord link but don’t know if it got thru so here it is again https://discord.gg/njetE8zU Wayne Sent from my iPhone On Feb 27, 2024, at 15:02, Chuck Guzis via cctalk wrote: On 2/27/24 14:42, Wayne S via cctalk wrote: Take a look at the Applesauce. It hooks up to a lot of different floppy drives and records and decodes the flux. Version2 of the hardware is being sourced and should be available in a few months. Good grief, there are more of these things floating around than one can shake a stick at. The Greasweazel is perhaps the cheapest, using a $3 ($1.30 or so from Aliexpress) STM32F103 "Blue Pill" board. It's almost trivial doing this if you don't need the "eye candy". Basically you run a timer in capture mode, with capture triggered by an edge on the drive's "read data" line. Modern MCUs don't even break a sweat doing this. It's nice seeing the proliferation after many years of harping on the subject... --Chuck
[cctalk] Re: Paper tape in casettes...
On 2/27/24 14:42, Wayne S via cctalk wrote: > Take a look at the Applesauce. > It hooks up to a lot of different floppy drives and records and decodes the > flux. > Version2 of the hardware is being sourced and should be available in a few > months. > Good grief, there are more of these things floating around than one can shake a stick at. The Greasweazel is perhaps the cheapest, using a $3 ($1.30 or so from Aliexpress) STM32F103 "Blue Pill" board. It's almost trivial doing this if you don't need the "eye candy". Basically you run a timer in capture mode, with capture triggered by an edge on the drive's "read data" line. Modern MCUs don't even break a sweat doing this. It's nice seeing the proliferation after many years of harping on the subject... --Chuck
[cctalk] Re: applesauce vs western digital emulator
but still only floppy speeds. maybe they have software mods for larger capacity, but still only floppy speeds. emulate the western digital chip and go as fast as the original machine can handle it. there were non-apple disk emulators (including one designed for automatic loom weavers or something). I think still would be far more expensive than circuitry to decode floppy drive data lines. --Carey > On 02/27/2024 4:42 PM CST Wayne S via cctalk wrote: > > > Take a look at the Applesauce. > It hooks up to a lot of different floppy drives and records and decodes the > flux. > Version2 of the hardware is being sourced and should be available in a few > months. >
[cctalk] Re: Paper tape in casettes...
> On 02/27/2024 12:29 PM CST paul.kimpel--- via cctalk > wrote: > Bitsavers has a collection of G-15 manuals. Rob Kolstad (formerly of BSDI) and I sat down last August to categorize his online scans. AFAICT he has the largest collection. (Of course I forgot to bring my copy of the technical manual with all the waveforms penciled in.) He and I need to get back to that project. It had been a long time (high school days!) since I looked at that doc. To an experienced engineer, it's now clear how much of a work of genius it was (so few gates!) No wonder I had trouble understanding it all as a teenager. > David Lovett has been restoring a G-15 for the System Source Computer Museum > in Maryland (US). Hmm. I don't remember if Rob told me about that project. He knows of two in Texas. Some of my old notes are at http://obscurecomputers.org/g15/index.html . mcl
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
On 2/27/24 14:09, Paul Koning via cctalk wrote: > Suppose you had schematics of, say, a KA-10. You could turn those gates into > VHDL or Verilog, and that should deliver an exact replica of the original > machine, bug for bug compatible. That assumes the timing quirks are > manageable, which for most machines should be true. (It isn't for a CDC > 6600.) A section manager from years ago mentioned to me that, as a fresh EE out of school, his first job at CDC was measuring the loops of (taper pin) wire on the 6600 to which Seymour had attached tags that said "tune". --Chuck
[cctalk] Re: Paper tape in casettes...
Take a look at the Applesauce. It hooks up to a lot of different floppy drives and records and decodes the flux. Version2 of the hardware is being sourced and should be available in a few months. Sent from my iPhone > On Feb 27, 2024, at 14:32, Martin Bishop via cctalk > wrote: > > >> >>> I would love to see a PDP-8 with 1/2 size flip chips using today's smaller >>> logic. > > Can you get the logic ? Especially the bus / backplane driving parts. > > https://retrocmp.com/projects/qbone/326-qbone-unibone-alternative-bus-drivers > Q-bus transceivers (DS8641 being a classic) are unobtainium in commercial > qtys, the substitutes listed seem little more available > Omnibus parts ... > > https://www.microchip.com/en-us/product/pic16f13145 > An 8..28 pin microcontroller with 32 (4-1) LUTs on 1.8 - 5 V supply, might > control output transistors for roll your own bus transceivers > Small, cheap and perhaps sufficiently fast / flexible; also, perhaps > competition for the 22V10 ? > > Martin > >
[cctalk] Re: Paper tape in casettes...
> On 02/27/2024 9:05 AM CST Jon Elson via cctalk wrote: > > I think the Bendix G-15 had cassettes for the 5-level tape > they used. I can confirm this from personal experience. mcl
[cctalk] Re: Paper tape in casettes...
>> I would love to see a PDP-8 with 1/2 size flip chips using today's smaller >> logic. Can you get the logic ? Especially the bus / backplane driving parts. https://retrocmp.com/projects/qbone/326-qbone-unibone-alternative-bus-drivers Q-bus transceivers (DS8641 being a classic) are unobtainium in commercial qtys, the substitutes listed seem little more available Omnibus parts ... https://www.microchip.com/en-us/product/pic16f13145 An 8..28 pin microcontroller with 32 (4-1) LUTs on 1.8 - 5 V supply, might control output transistors for roll your own bus transceivers Small, cheap and perhaps sufficiently fast / flexible; also, perhaps competition for the 22V10 ? Martin
[cctalk] Resurrecting old microcomputers
OK, probably the hardest part is the floppy disk, as the mechanics corrode over time more than chips. People have built electronics to connect to a floppy cable and emulate a drive electronically. Difficult to catch the timing on flux changes and digitize. More than I want to spend at this time. Couldn't somebody more clever than me develop something that would plug into a Western Digital floppy disk controller socket, catch the commands to the device directly? Probably need to be an FPGA, to actively monitor and catch the bus signals. Yes, and apple would have to have it's own, probably a card to plug into the bus. Although I think I have an apple ][ 3rd party card what uses a WD controller and standards shugart style drives. probably the disks are incompatible with those from the apple ][ card, which is why I then bought a 3rd party apple style card and disk (but did not do enough with any of them to remember details). IIRC there was one other early PC that did not use WD floppy controller chips. connect this wd emulator via USB to a modern tablet/desktop/smartphone where storage and heavy lifting would be done. With minimal changes to the original operating system, define floppy with at least 255 tracks of (?) at least 255 records of (?) 4096 bytes, effectively making a hard disk, and of course as fast as it can transfer data. can't do that with something grabbing signals off the floppy cable. the emulation would initially be storing track images. Later it could understand the floppy formats and actually store the data in PC files...shareable between Apple ][, Atari, TRS-80 (all flavors), etc, etc, and the modern PC. the WD emulator could emulate the original floppy controller also, so a computer could have both the original mechanical floppy and modern high volume storage. That would require a clip to wherever the floppy select lines were stored.
[cctalk] Re: recreating old computers [was: Paper tape in casettes...]
> On Feb 27, 2024, at 4:49 PM, CAREY SCHUG via cctalk > wrote: > > Religion warning: I was a mainframer. Since at any practical budget, they > can only be emulated, Depends on your definition of emulated. Is an FPGA version merely an "emulation"? You might say yes if it's a functional model. Arguably no, if it's a gate level model. Suppose you had schematics of, say, a KA-10. You could turn those gates into VHDL or Verilog, and that should deliver an exact replica of the original machine, bug for bug compatible. That assumes the timing quirks are manageable, which for most machines should be true. (It isn't for a CDC 6600.) paul
[cctalk] recreating old computers [was: Paper tape in casettes...]
Religion warning: I was a mainframer. Since at any practical budget, they can only be emulated, for small computers, I would like pure hardware as much as possible, and what did or could have existed (no fpga). What I wish somebody would create is an S-100 card (probably with a raspberry pie daughter running simulation for future upgradeability) that, initially emulates a complete Byte-8 or Imsai computer including memory and disk images on sdc cards, 24x40 display on an HDMI display and USB keyboard. serial and parallel ports emulated. software upgrades could be: -- a full web page with clickable front panels and ascii terminals. -- support other CPU cards, e.g. 8088, 68000, 6502, etc but the big thing: bidirectional ports on all S-100 data lines. go into supervisory mode and define --this memory range go to the s-100 bus so you can get that old 8k memory card working. --this io range go to s-100 bus to get the old printer interface, etc going --eventually down to just the CPU, pull this new card, put in old CPU and you have an original. --possibly reverse also, so would be super board emulating memory, disk, etc for an original CPU card. AND maybe headers to connect to ribbon cables to do the same functions to recover other busses: apple, TRS-80, OSI, unibus, isa, eisa, s-bus --Carey > On 02/27/2024 2:13 PM CST Doug McIntyre via cctalk > wrote: > > > On Tue, Feb 27, 2024 at 11:10:34AM -0700, ben via cctalk wrote: > > PS: With low cost Chinese PCB's and vintage parts, why are people not > > building real hardware replica's of interesting machines. > > But they are.. > I can't tell what you'd find interesting since the list is pretty wide. > > I've got an Apple I replica board that someday I intend to populate and get > running. > > You've got the ReAmiga project producing new boards for using up old parts on > broken boards. > https://www.reamiga.info/?page_id=36 > > One thing that I find interesting (although I'd never do it), is a board to > emulate > a 68000 CPU at much higher speeds running barebones emulator on a Raspberry > Pi. > Aimed at Amiga A1200 again. > https://wiki.amiga.org/index.php?title=Pistorm32-Lite > > I've put together my IMSAI 8080 frontpanel kit, with the CPU emulated on an > ESP32. > https://thehighnibble.com/imsai8080/ > > Or they are about to ship out the PiDP-10 blinkenlights kits > https://obsolescence.dev/pidp10.html > The CPU again emulated on a RaPi, but all new boards and plastic for the > console kit > I'm not sure if anybody has ever thought about making flipchip boards > themselves though. > Although they might have been.. > https://forum.vcfed.org/index.php?threads/a-general-purpose-flip-chip-adapter-board-worth-doing.1228572/
[cctalk] Re: PB-440 [was: Paper tape in casettes...]
On 2/27/24 13:28, CAREY SCHUG wrote: > you are correct. Packard Bell. apologies. And the picture on page 8 is (or > is close to) > the paper tape reader I remember. So many fun things to program (I > programmed in octal only). I like the description on that same page referring to "octal arabic character" as opposed to, say, Babylonian character. :) --Chuck
[cctalk] Re: Paper tape in casettes...
On 2024-02-27 1:13 p.m., Doug McIntyre via cctalk wrote: On Tue, Feb 27, 2024 at 11:10:34AM -0700, ben via cctalk wrote: PS: With low cost Chinese PCB's and vintage parts, why are people not building real hardware replica's of interesting machines. But they are.. I can't tell what you'd find interesting since the list is pretty wide. Anything not APPLE or IBM or DEC or a PI-emulation for a home brew computer. I've got an Apple I replica board that someday I intend to populate and get running. 1) Get a good power supply 2) hack in a 6809. 3) get a good power supply. You've got the ReAmiga project producing new boards for using up old parts on broken boards. https://www.reamiga.info/?page_id=36 One thing that I find interesting (although I'd never do it), is a board to emulate a 68000 CPU at much higher speeds running barebones emulator on a Raspberry Pi. Aimed at Amiga A1200 again. https://wiki.amiga.org/index.php?title=Pistorm32-Lite I've put together my IMSAI 8080 frontpanel kit, with the CPU emulated on an ESP32. https://thehighnibble.com/imsai8080/ I had z80/s100 kit once, but the power supply failed taking every thing out. Or they are about to ship out the PiDP-10 blinkenlights kits https://obsolescence.dev/pidp10.html The CPU again emulated on a RaPi, but all new boards and plastic for the console kit I think the PI is too cheap of computer build wise for emulation of any system. It might blink your lights, but never run 20 users timesharing. > I'm not sure if anybody has ever thought about making flipchip boards themselves though. > Although they might have been.. > https://forum.vcfed.org/index.php?threads/a-general-purpose-flip-chip-adapter-board-worth-doing.1228572/ Small PCB's run at $5 each and PAL 22v10 in each could replace a lot simple cards. I would love to see a PDP-8 with 1/2 size flip chips using today's smaller logic. A good home brew computer is what I am looking for. In hindsight I want 18 bit addressing (bytes optional) and single word memory ref's. Since 2901 alu's are 4 bits wide, 20,24,28 bits are my only option for a COMPUTER not for digital controller faking it. Still working on the pro-type stage here. For test pcb's I have, good source of Chinese toggle switches with a PCB foot print. https://www.ebay.ca/itm/143887059040 Hex displays are here. https://www.ebay.ca/itm/281809099152
[cctalk] PB-440 [was: Paper tape in casettes...]
you are correct. Packard Bell. apologies. And the picture on page 8 is (or is close to) the paper tape reader I remember. So many fun things to program (I programmed in octal only). conditional instructions were "skip if", so if the first microinstruction in the word, applied to the second, if the second, applied to the next word, that is, 2 micro instructions, the first of which might also be a conditional... two relative jumps in one word allowed a jump to be twice as big. I *think* I should have the microcode programming book for this on paper. all boxed up when I got married and never unboxed after the divorce. brown and black cover. --Carey > On 02/27/2024 12:40 PM CST Chuck Guzis via cctalk > wrote: > > > On 2/27/24 10:10, ben via cctalk wrote: > > Is the "PB" Pitney-Bowes or Packard-Bell? I note that only because that > Raytheon bought out Packard-Bell's computer operation and re-dubbed > their models. So a Packard-Bell PB 250 became the Raytheon PB 250. > > As regards the 440, it's on my short list of interesting "hybrid" > computers of the 1960s, which was a hot topic then: It was part of the > TRICE setup: > > http://www.bitsavers.org/pdf/raytheon/trice/TRICE_440_Oct64.pdf > > --Chuck > > On 2024-02-27 9:20 a.m., CAREY SCHUG via cctalk wrote: > >> It's not a cassette, but the PB-440 (Pitney-Bowes), renamed Raytheon > >> 440 and its upgrade the raytheon 520 had a large reel paper tape with > >> a bidirectional read and an "operating system" Load the os, say we > >> want to run fortran, spin down to fortran, read the program in on 80 > >> column cards (probably 2 pass, I don'trecall), automatically reload > >> the monitor when done, read and execute the program from cards. > >> Frequently used programs could be on the OS paper tape reel. > >> > >> btw, that computer was user level microcode. multiple "machine" > >> definitions, with typical 24 bit word, one instruction set optimized > >> for fortran execution, one for fortran compilation, etc (don't > >> remember exactly, as I only programmed in the microcode of mostly 2 > >> micro instructions per word).
[cctalk] Re: Paper tape in casettes...
On Tue, Feb 27, 2024 at 11:10:34AM -0700, ben via cctalk wrote: > PS: With low cost Chinese PCB's and vintage parts, why are people not > building real hardware replica's of interesting machines. But they are.. I can't tell what you'd find interesting since the list is pretty wide. I've got an Apple I replica board that someday I intend to populate and get running. You've got the ReAmiga project producing new boards for using up old parts on broken boards. https://www.reamiga.info/?page_id=36 One thing that I find interesting (although I'd never do it), is a board to emulate a 68000 CPU at much higher speeds running barebones emulator on a Raspberry Pi. Aimed at Amiga A1200 again. https://wiki.amiga.org/index.php?title=Pistorm32-Lite I've put together my IMSAI 8080 frontpanel kit, with the CPU emulated on an ESP32. https://thehighnibble.com/imsai8080/ Or they are about to ship out the PiDP-10 blinkenlights kits https://obsolescence.dev/pidp10.html The CPU again emulated on a RaPi, but all new boards and plastic for the console kit I'm not sure if anybody has ever thought about making flipchip boards themselves though. Although they might have been.. https://forum.vcfed.org/index.php?threads/a-general-purpose-flip-chip-adapter-board-worth-doing.1228572/
[cctalk] Re: Paper tape in casettes...
On 2/27/24 10:10, ben via cctalk wrote: > On 2024-02-27 9:20 a.m., CAREY SCHUG via cctalk wrote: >> It's not a cassette, but the PB-440 (Pitney-Bowes), renamed Raytheon >> 440 and its upgrade the raytheon 520 had a large reel paper tape with >> a bidirectional read and an "operating system" Load the os, say we >> want to run fortran, spin down to fortran, read the program in on 80 >> column cards (probably 2 pass, I don'trecall), automatically reload >> the monitor when done, read and execute the program from cards. >> Frequently used programs could be on the OS paper tape reel. >> >> btw, that computer was user level microcode. multiple "machine" >> definitions, with typical 24 bit word, one instruction set optimized >> for fortran execution, one for fortran compilation, etc (don't >> remember exactly, as I only programmed in the microcode of mostly 2 >> micro instructions per word). Is the "PB" Pitney-Bowes or Packard-Bell? I note that only because that Raytheon bought out Packard-Bell's computer operation and re-dubbed their models. So a Packard-Bell PB 250 became the Raytheon PB 250. As regards the 440, it's on my short list of interesting "hybrid" computers of the 1960s, which was a hot topic then: It was part of the TRICE setup: http://www.bitsavers.org/pdf/raytheon/trice/TRICE_440_Oct64.pdf --Chuck
[cctalk] Re: Paper tape in casettes...
erik＠baigar.de wrote: > > > think the Bendix G-15 had cassettes for the 5-level > > tape > > they used. > Aha, interesting! Did a short search, but have not been able to > find a picture of a casette. Just a pile of paper tape instead ;-) > > https://images.app.goo.gl/HYqkpYHJUxZeGfiA8 Bitsavers has a collection of G-15 manuals. For a picture of an open cassette, see PDF page 27 in http://bitsavers.org/pdf/bendix/g-15/60061400_G15D_Parts_Manual.pdf. Also see PDF page 18 in http://bitsavers.org/pdf/bendix/g-15/G15_Operating_Man_Jul59.pdf. David Lovett has been restoring a G-15 for the System Source Computer Museum in Maryland (US). He regularly publishes videos of his progress, such as this one: https://www.youtube.com/watch?v=WNfR4DmoZQU=ygUWYmVuZGl4IGctMTUgcGFwZXIgdGFwZQ%3D%3D To see more, try searching youtube.com for "bendix g-15 paper tape".
[cctalk] Re: Paper tape in casettes...
On 2024-02-27 9:20 a.m., CAREY SCHUG via cctalk wrote: It's not a cassette, but the PB-440 (Pitney-Bowes), renamed Raytheon 440 and its upgrade the raytheon 520 had a large reel paper tape with a bidirectional read and an "operating system" Load the os, say we want to run fortran, spin down to fortran, read the program in on 80 column cards (probably 2 pass, I don'trecall), automatically reload the monitor when done, read and execute the program from cards. Frequently used programs could be on the OS paper tape reel. btw, that computer was user level microcode. multiple "machine" definitions, with typical 24 bit word, one instruction set optimized for fortran execution, one for fortran compilation, etc (don't remember exactly, as I only programmed in the microcode of mostly 2 micro instructions per word). --Carey Where is some document ion on that machine? I finally got around to building the TTL home-brew computer I wanted from the 1970's and now I need all the goodies like paper tape and i/o that is Algol ready. :) Ben. OK I cheated using Cmos 2901's and 22v10's, but that is what I had to make the PCB layouts easy.I don't think 1 74H04 counts for making it a TTL computer. :) PS: With low cost Chinese PCB's and vintage parts, why are people not building real hardware replica's of interesting machines.
[cctalk] Re: Paper tape in casettes...
On 2/27/24 08:58, erik--- via cctalk wrote: Hi Jon! think the Bendix G-15 had cassettes for the 5-level tape they used. Aha, interesting! Did a short search, but have not been able to find a picture of a casette. Just a pile of paper tape instead ;-) https://images.app.goo.gl/HYqkpYHJUxZeGfiA8 Yes, the cassette is visible right below where the tape is coming out of the punch, Most other photos of the G-15 show a shiny aluminum rectangle near the top front of the computer. That is the cassette. There is a horizontal lever across the cassette that holds it in place. Jon
[cctalk] Re: Paper tape in casettes...
It's not a cassette, but the PB-440 (Pitney-Bowes), renamed Raytheon 440 and its upgrade the raytheon 520 had a large reel paper tape with a bidirectional read and an "operating system" Load the os, say we want to run fortran, spin down to fortran, read the program in on 80 column cards (probably 2 pass, I don'trecall), automatically reload the monitor when done, read and execute the program from cards. Frequently used programs could be on the OS paper tape reel. btw, that computer was user level microcode. multiple "machine" definitions, with typical 24 bit word, one instruction set optimized for fortran execution, one for fortran compilation, etc (don't remember exactly, as I only programmed in the microcode of mostly 2 micro instructions per word). --Carey > On 02/27/2024 8:58 AM CST erik--- via cctalk wrote: > > > Hi Jon! > > > think the Bendix G-15 had cassettes for the 5-level tape > > they used. >
[cctalk] Re: RD54 Maxtor XT-2190 w/one long meep
Get a sheet of glass. In a not too dusty area (hint A/C has filers usually) gloves on Top off glass on - all will be revealed. Rod - Digital Equipment Corporation 1975 - 1985 On 27/02/2024 03:50, Chris Zach via cctalk wrote: Oh wait, that sound? Over and over? I had a RD54 type drive that I hit with a magnet by mistake and took out the servo platter. Got that sound, over and over because the drive used servo loop positioning and couldn't find the servo track. Since you probably didn't do this, check to see if you get a signal off the servo head, and the preamps there. That might actually be it. C On 2/26/2024 5:28 PM, Jacob Ritorto via cctalk wrote: Thanks for the good ideas and convo everyone. Now please do note that I can definitely hear motor/platter spinup happening so it's definitely not "heads stuck to platter" stiction. I hear the lock unlatch and I *think* I even hear the heads load and fly (comparing what I hear on this drive to other drives I've actually seen the guts of in flying action) so I substantially doubt it's "arm stuck to lock pad goo" stiction. So we've made it through a lot of the powerup sequence and the problem is at the final part - the track scan up and back down the surface - the phase when the signature "...blearrt-meelrp..." happens :) And yes I believe from memory that XT-2190 is supposed to make the same track scan noise as the XT-1140 (I have an XT-1140 running perfectly as a fake RD54 in another pdp here). So could my behaviour of being hung at the final phase - the track scan noise - be the result of a lost servo track? Thinking about that, didn't someone on this list kill an XT-2190 recently by taking an outrageous magnet to it? Did you get the same track scan failure as I'm getting? Confused electronics on the PCB? Something else? Where would one begin diagnosing this particular problem? I did try the wrist twist torquing thing. And lightly whacking side of housing with palm of hand during track scan noise. Declining to do that hard, tho. Powered off and back on (to retry) probably near a hundred times now. Heated it gently in front of our forced-air furnace duct until comfortably warm to touch - probably near 105 F. All these produced absolutely zero behaviour change. thx jake
[cctalk] Re: Paper tape in casettes...
Hi Jon! > think the Bendix G-15 had cassettes for the 5-level tape > they used. Aha, interesting! Did a short search, but have not been able to find a picture of a casette. Just a pile of paper tape instead ;-) https://images.app.goo.gl/HYqkpYHJUxZeGfiA8 > of mylar tape instead of paper. OS boot tapes might be punched > on that. Yes, for heavy use (and e.g. humid environments), the mil guys obviously used Mylar or heavily oiled tape. Although not experrienced myself, I was told that the Mylar tape cuts through the guiding pins of the readers over time. And yes, it also may easily cut one's fingers ;-) > much like plain paper tape, and simple mylar alone. The latter often > comes metallized on one side, and is glossy. Yes, that is the one within the casette and the aluminum as you expect is for optical reading (Most plastics including Mylar are quite transparent for IR light and in the old days, when thungsten bulbs where used, the IR part of the light was the major part contributing to the response of the photodiodes! > input medium for the university mainframe computer (Electrologica X8), > they used optical readers rated at 2000 characters per second. Wow - that is indeed pretty fast!!! My FACIT is 1200cps maximum and stopping "on character" as it is called is VERY hard at that speed. But buffering helps here and in case of the 920M, the casette is used for, there was no buffering. So software needs to be read in one run. Best wishes, Erik. ''~`` ( o o ) +--.oooO--(_)--Oooo.-+ | Dr. Erik Baigar Inertial Navigation & | | Salzstrasse 1 .oooOVintage Computer | | D87616 Marktoberdorf ( ) Oooo.Hobbyist / Physicist | | e...@baigar.de +--\ (( )---+ | www.baigar.de| \_)) / +--+ (_/
[cctalk] Re: Paper tape in casettes...
On 2/27/24 00:17, Dr. Erik Baigar via cctalk wrote: I wonder whether anyone kows if someone else had the idea of putting paper/mylar tape into a casette for repeated use e.g. to load an OS or similar. I think the Bendix G-15 had cassettes for the 5-level tape they used. I had an optical reader that was designed for some kind of cassette, but I never had the cassettes. But, it could be used with open spools of tape. Jon
[cctalk] Re: Paper tape in casettes...
> On Feb 27, 2024, at 1:17 AM, Dr. Erik Baigar via cctalk > wrote: > > > Hi there - recently I posted a small video on a rugged > paper tape casette... > > https://www.youtube.com/watch?v=O2jnThYsPKc > > I wonder whether anyone kows if someone else had the idea > of putting paper/mylar tape into a casette for repeated use > e.g. to load an OS or similar. > > Best wishes, > > Erik. Interesting! The only "heavy use" approach to paper tape I have seen is the use of mylar tape instead of paper. OS boot tapes might be punched on that. My father had a machine in his lab (precision measurement lab) in which a tape of correction data was used. That was punched on mylar. I think there are two variants of mylar tape: mylar sandwiched with paper, which looks much like plain paper tape, and simple mylar alone. The latter often comes metallized on one side, and is glossy. The metallization I suspect is for reliable optical reading, to avoid problems with the mylar alone being too translucent. Optical readers are pretty gentle in their tape handling even at high speed, at least if they can avoid starting and stopping. At TU Eindhoven, where paper tape was the exclusive input medium for the university mainframe computer (Electrologica X8), they used optical readers rated at 2000 characters per second. These could start and stop very quickly but in normal use were spooled to drum so they were moving all the time. The input side would be a roll; on the way out of the reader the tape would drop into a bucket from which it could be rewound with a separate tape winder. I don't remember if the X8 tape reader could stop between characters. I know the X1 reader (1000 cps I think) could do so, which is quite an amazing mechanical accomplishment. paul
