Re: Advice needed: Entry point into things PDP-8
Ethan Dicks wrote: On Mon, Oct 22, 2018 at 10:39 PM Carlos E Murillo-Sanchez via cctalk wrote: you. The thing is, I would like to have something pdp8-ish that would allow me to play a little bit with the programming languages that were available for these machines, FORTRAN 4K and FORTRAN IV in particular. Now, I would love to be able to time some FORTRAN jobs just to get an idea about what it was like back then. I am aware of PiDP-8, simh, as well as SBC6120, SBC6120RBC. I would probably do all the things but in a particular order. If my goal was to learn PDP-8 software, I would just start with simh running on anything. I have a PiDP-8. It's nice. You definitely get the feel of running an older PDP-8 (except no noise for floppy drives or DECtape, and no seek time) but under the blinky covers, it's running simh. You can learn everything about the configuration of PDP-8 models, about memory, and all the programming languages with simh. From there, consider a PiDP-8 if you want a quick junior-sized emulated machine for the look and feel of things. The SBC6120 with FB6120 is also nice. I have one. -snip- Based on the answers from everyone (Thanks!), I think that I will grab one of the RaspberryPi's laying around and start using the PiDP-8 software or plain simH while I can procure the hardware side of PiDP-8; I think that I'll perform the serial console hack on the Pi. I will continue to research options for programming the GALs in the SBC6120 or SBC6120RBC, since I have one HD6120 chip and it would be a waste not to use it. The OSI Processor Lab route seems interesting, especially since I have three HM6100 chips, but I think that it isn't in a stage that allows reproducing the PDP-8 usage experience. If you guys can recommend a cheap programmer that handles the ATF22V10CQZ-20PU and ATF16V8BQL-15PU (SBC6120) without problems, I am all ears. >From there, one of the challenges of repairing your VT78 and VT278 boards is there's no blinkenlights console to assess repair status during the repair or to try to toggle in test programs. Replacing a ROM is easy enough, even if you have to make a pin-swapping socket adapter to use a modern EPROM (I don't know what type of ROM is in the VT78, but it's possible that it's something standard like a 2708 or 2716). -ethan The control panel ROM in the vt78 is proprietary (12bit data width), so it would have to be replaced by a more complex circuit. But one of the three vt78s that I have does have that chip, so this is an issue only if I try to restore the other two boards. Carlos.
Re: Advice needed: Entry point into things PDP-8
On Mon, Oct 22, 2018 at 10:39 PM Carlos E Murillo-Sanchez via cctalk wrote: > you. The thing > is, I would like to have something pdp8-ish that would allow me to play > a little bit > with the programming languages that were available for these machines, > FORTRAN 4K and > FORTRAN IV in particular. Now, I would love to be able to time some > FORTRAN jobs just > to get an idea about what it was like back then. I am aware of PiDP-8, > simh, as well as > SBC6120, SBC6120RBC. I would probably do all the things but in a particular order. If my goal was to learn PDP-8 software, I would just start with simh running on anything. I have a PiDP-8. It's nice. You definitely get the feel of running an older PDP-8 (except no noise for floppy drives or DECtape, and no seek time) but under the blinky covers, it's running simh. You can learn everything about the configuration of PDP-8 models, about memory, and all the programming languages with simh. From there, consider a PiDP-8 if you want a quick junior-sized emulated machine for the look and feel of things. The SBC6120 with FB6120 is also nice. I have one. Unlike the PiDP-8, the SBC6120 has a native 12-bit microprocessor (IM6120) and isn't emulating anything except running some front panel ROM code to handle disks in a way that hides the details from the OS/8 side of things (much like the DECmates do). Unfortunately, they are expensive. Not many were made and they weren't exactly cheap when new. As for the GAL programmer, the GALs in the SBC6120 are rather ordinary but, yes, some programmers can't handle them. I have multiple device programmers and even the one from 1990 can program 20 and 24-pin GALs (I'm not sure about newer programmers - I don't have one because my older ones work fine). Someone on the list could probably bang them out for you for a few dollars unless you really wanted to own the entire hardware toolchain. >From there, one of the challenges of repairing your VT78 and VT278 boards is there's no blinkenlights console to assess repair status during the repair or to try to toggle in test programs. Replacing a ROM is easy enough, even if you have to make a pin-swapping socket adapter to use a modern EPROM (I don't know what type of ROM is in the VT78, but it's possible that it's something standard like a 2708 or 2716). Getting replacement parts for your VT278 is probably not all _that_ hard - one likely source is a DECmate II or III board, if you can find a spare. Last time I bought one, it was about $50 but it probably has gone up a little. The VT278 does have a compatibility issue with the console SLU (03/04) and the flags. That's why there's OS/278 in the DECUS collection. If you were going to write your own code from scratch, you'd have to take the operation of the console device into account when writing your TTY code, and you might not be able to just run anything you find. I have a VT278 but have only run WPS-8 on it, not OS/278 so I can't provide deep details. You would likely want an RX02 (and cable) if you were going to resurrect the VT278. The cable can be made (DB25 one end, DC37 other end, and the pinouts are available). Inside the VT278 pedestal is a _real_ RX02 but there's a simple 40-pin-to-DB-25 passive board inside the case, much like the one in an RX02 for a MINC-11, and, again, this can be made new. Finding any RX02 drive is an exercise in shopping and paying freight, but then you'll need someone to at least cut some starter floppies for you. So if you are going to go the emulation route, I'd start with just downloading simh and some OS/8 image files (RK05 or RX02) and learning the software side of things. This may generate enough interest to want to explore the hardware side of things, and for that, you definitely have a swath of projects in front of you with varying degrees of cost and effort. -ethan
Re: Advice needed: Entry point into things PDP-8
On Tue, Oct 23, 2018 at 8:11 AM systems_glitch via cctalk wrote: > > There's also our Ohio Scientific 560Z "Processor Lab" reproduction: > > http://www.glitchwrks.com/2017/02/26/osi-560z-build That's fun. For a long time now, I've wanted to noodle around on a Challenger 3. We had a family friend in the 1970s who had one and I used to go visit and spend hours on it. I was using PETs every week at the same time so it was a bit of a shift to a floppy-based system and one that had 3 CPUs on top of that! I started fiddling with PDP-8s about 4-5 years later and was surprised to learn there was a PDP-8-on-a-chip (IM6100 then later then IM6120). Very cool that you've made it available now. I just don't think I'll ever run across a Challenger 3. I haven't in the past 30 years, and I live about 2 hours from where they were made. Was the original 560Z a popular board? I'm guessing it was a niche product. -ethan
Re: Advice needed: Entry point into things PDP-8
There's also our Ohio Scientific 560Z "Processor Lab" reproduction: http://www.glitchwrks.com/2017/02/26/osi-560z-build It uses the Intersil IM6100 and executes PDP-8 code. Memory management is implemented in handlers written in 6502 assembly on the host system, so you can have whatever memory management you like. I believe one of the guys on the osiweb.org forums has PDP-8/e memory management working. I don't know if he has OS/8 running yet, but does have at least FOCAL going. You of course need a 12-bit memory board, which we also make (uses modern components, works with FeRAM for a core-like experience). And you'll need some sort of host system, the simplest being an Ohio Scientific 502 at the moment (basically a single-board 6502 system with serial console). That's probably the cheapest/most reliable *non-emulation* route. Of course, emulation is going to be both cheaper and more reliable. Thanks, Jonathan On Tue, Oct 23, 2018 at 12:17 AM Paul Anderson via cctalk < cctalk@classiccmp.org> wrote: > Hi Carlos, > > With the cost of PDP-8 parts and the need for maintenance and repair, if > you can find an emulator that will do what you want, go for it. > > Paul > > On Mon, Oct 22, 2018 at 10:39 PM Carlos E Murillo-Sanchez via cctalk < > cctalk@classiccmp.org> wrote: > > > Greetings all... > > > > I have been pondering something and would love to receive feedback from > > you. The thing > > is, I would like to have something pdp8-ish that would allow me to play > > a little bit > > with the programming languages that were available for these machines, > > FORTRAN 4K and > > FORTRAN IV in particular. Now, I would love to be able to time some > > FORTRAN jobs just > > to get an idea about what it was like back then. I am aware of PiDP-8, > > simh, as well as > > SBC6120, SBC6120RBC. > > > > I happen to have three VT78 cpu boards (sans the RAM board) and two > > vt278 cpu boards. > > All were in rather sorry condition; I picked them up from a junk pile > > that was stacked > > several feet high and in which the contents were mostly random. Thus, > > the VT78 boards' > > components were scratched and in fact two of them are missing the > > control panel ROM chip. > > Otherwise they are complete, but I am missing the RAM boards. The VT278 > > boards > > were further abused by someone who yanked out the oscillators and a few > > TTL chips, > > damaging several traces, which I have now repaired. Alas, only one of > > them has the > > HM6120 cpu chip, and I do not know if it is good or not. Both are > > missing the SMC5037 > > CRT generator chip. Other than that, they are complete. > > > > So, now that we all know what I have, let me say out loud what I've been > > thinking: > > > > If I try to build actual hardware: > > > > I've read that the VT278 has serious software compatibility issues with > > older software > > due to the use of the HM6121 I/O chip. So even if I get an adequate > > keyboard, buy the > > CRT chip and manage to use it to drive a monitor, I would need an > > original floppy drive > > system and media, because I do not have the DP278 serial comms board > > that would allow me > > to send the VT278 a program to run; > > > > For the VT78, I would need to hack a memory board, and, since it can be > > coaxed to accept > > a program to run if it is fooled into thinking that it is loading a > > program from an > > MR78/paper tape, perhaps I could make it boot something. I would need > > to wire-up > > and arduino or something like it to translate the keyboard and display > > terminal > > chatter in the serial console into something usable. But, that's three > > hardware > > projects (memory board, MR78-like contraption, microcontrolled serial > > console > > translator)... > > > > The last hardware option is to go and make an SBC6120RBC; I would need > > to buy > > programmers for the GAL/PAL devices, and I've heard that not all > > programmers can deal > > with the kind of chips used in it. And, if it turns out that the HM6120 > > chip that I > > have is bad, I would have to hunt down one of those rare beasts.. It > > would be awesome, though, > > to have an SBC6120RBC up and running, and be able to time actual > > hardware running > > FORTRAN. > > > > And then comes the emulation option, with the PiDP-8. I have to say > > that the emulation > > of the blinkenlights is very, very attractive to me, and this option is > > a no-brainer > > hardware-wise. > > > > So... am I missing something in my estimation of the effort involved in > > these options? > > > > What would _you_ do? > > > > Carlos. > > > > >
Re: Advice needed: Entry point into things PDP-8
Hi Carlos, With the cost of PDP-8 parts and the need for maintenance and repair, if you can find an emulator that will do what you want, go for it. Paul On Mon, Oct 22, 2018 at 10:39 PM Carlos E Murillo-Sanchez via cctalk < cctalk@classiccmp.org> wrote: > Greetings all... > > I have been pondering something and would love to receive feedback from > you. The thing > is, I would like to have something pdp8-ish that would allow me to play > a little bit > with the programming languages that were available for these machines, > FORTRAN 4K and > FORTRAN IV in particular. Now, I would love to be able to time some > FORTRAN jobs just > to get an idea about what it was like back then. I am aware of PiDP-8, > simh, as well as > SBC6120, SBC6120RBC. > > I happen to have three VT78 cpu boards (sans the RAM board) and two > vt278 cpu boards. > All were in rather sorry condition; I picked them up from a junk pile > that was stacked > several feet high and in which the contents were mostly random. Thus, > the VT78 boards' > components were scratched and in fact two of them are missing the > control panel ROM chip. > Otherwise they are complete, but I am missing the RAM boards. The VT278 > boards > were further abused by someone who yanked out the oscillators and a few > TTL chips, > damaging several traces, which I have now repaired. Alas, only one of > them has the > HM6120 cpu chip, and I do not know if it is good or not. Both are > missing the SMC5037 > CRT generator chip. Other than that, they are complete. > > So, now that we all know what I have, let me say out loud what I've been > thinking: > > If I try to build actual hardware: > > I've read that the VT278 has serious software compatibility issues with > older software > due to the use of the HM6121 I/O chip. So even if I get an adequate > keyboard, buy the > CRT chip and manage to use it to drive a monitor, I would need an > original floppy drive > system and media, because I do not have the DP278 serial comms board > that would allow me > to send the VT278 a program to run; > > For the VT78, I would need to hack a memory board, and, since it can be > coaxed to accept > a program to run if it is fooled into thinking that it is loading a > program from an > MR78/paper tape, perhaps I could make it boot something. I would need > to wire-up > and arduino or something like it to translate the keyboard and display > terminal > chatter in the serial console into something usable. But, that's three > hardware > projects (memory board, MR78-like contraption, microcontrolled serial > console > translator)... > > The last hardware option is to go and make an SBC6120RBC; I would need > to buy > programmers for the GAL/PAL devices, and I've heard that not all > programmers can deal > with the kind of chips used in it. And, if it turns out that the HM6120 > chip that I > have is bad, I would have to hunt down one of those rare beasts.. It > would be awesome, though, > to have an SBC6120RBC up and running, and be able to time actual > hardware running > FORTRAN. > > And then comes the emulation option, with the PiDP-8. I have to say > that the emulation > of the blinkenlights is very, very attractive to me, and this option is > a no-brainer > hardware-wise. > > So... am I missing something in my estimation of the effort involved in > these options? > > What would _you_ do? > > Carlos. > >
Re: Advice needed: Entry point into things PDP-8
On Mon, Oct 22, 2018 at 11:39 PM Carlos E Murillo-Sanchez via cctalk < cctalk@classiccmp.org> wrote: > Greetings all... > > I have been pondering something and would love to receive feedback from > you. The thing > is, I would like to have something pdp8-ish that would allow me to play > a little bit > with the programming languages that were available for these machines, > FORTRAN 4K and > FORTRAN IV in particular. Now, I would love to be able to time some > FORTRAN jobs just > to get an idea about what it was like back then. I am aware of PiDP-8, > simh, as well as > SBC6120, SBC6120RBC. > > > Carlos, My opinionGet a PiDP8. They're great for so many things including testing, file transfer, and making disks. I have mine set to boot into simH via serial terminal so it will immediately act like a PDP 8 running OS/8. Once you get a working real PDP8, whatever, the type you can use the PiDP8 safely to experiment, compare and contrast, build media, etc I have documented the process on my web site, and there are many others who have also done this. Bill
