Ian Hirschsohn - DISSPLA, Superset Inc. and sad news
As some here know, I collect some dusty deck fortran graphics. We have MOVIE.BYU up and running! (Thanks Douglas Taylor and Emanuel Steibler). Ian built AMD 2901 bit slice hardware to run his graphics, it was called SuperSet, and was very quick for the 1980s. Architecture was 48 bit, A=B op C, similar to DSPs. Compiler processed fortran to this 48 bit 2900 hardware (he wrote the compiler too). Small package, a dormitory size refrigerator with all I/O to drive plotters and graphics terminals. I went to look him up today, as he is not far from me in LA, San Diego, and a fellow R/C flier, and chat about the old Superset days, we did SIGGRAPH many times together. Well, he is dead I find out, killed last year in Mexico is what the news says, buried in a well with his wife. They went often, many times a year. Randy
Re: LSSM quick update
That is fantastic, so fast to get it done. B On Sat, Jul 31, 2021 at 12:32 AM Mike Loewen via cctalk < cctalk@classiccmp.org> wrote: > >The A/C is in and running! Tomorrow and Sunday we reassemble the > exhibit floor and clean up the mess, just in time for the 60-person > group tour on Monday. > > -- > Dave McGuire, AK4HZ > New Kensington, PA > > Thanks to all who contributed to the new A/C! >
LSSM quick update
The A/C is in and running! Tomorrow and Sunday we reassemble the exhibit floor and clean up the mess, just in time for the 60-person group tour on Monday. -- Dave McGuire, AK4HZ New Kensington, PA Thanks to all who contributed to the new A/C!
Re: Reading MT/ST Tapes
On 7/30/21 6:22 PM, Paul Berger via cctalk wrote: > The MT/ST did pretty good for being a electro-mechanical device,all the > logic was relays in it. I seem to recall many years ago one of the old > OP guys telling me that it write in stripes across the tape. It would > have to be some very simple format because it would be hard to have the > thing sync on headers with only a little relay logic. Like a motion picture film projector. Brings the tape to a complete stop for each character and then scans across it with a single head; going in, the character is read, going out, the character just read is checked. I assume (but am not sure) that if the check fails, a retry is attempted. The head moves at 45 ips and records bits at a 45 degree angle relative to the tape axis. This is so the tape can be scanned without moving the head for a mark in the control track (reading parallel to the axis of tape movement) or reading characters with the tape stopped (reading orthogonal to the tape movement. Obviously, precise tape positioning is important (even at 20 cpi), hence the sprocket feed. In off-list conversations with others, I keep trying to impress on the younger folks that this is basically an electro-mechanical device with heavy emphasis on mechanics. After all, the people who serviced these things were typewriter repair people. I doubt that the innards of the MT/ST were much more complex than those of the Selectric itself. (One of these days, I'll get up the nerve to replace the motor drive belt in my Correcting Selectric III). But when you've grown up with microprocessors, I guess it can be hard to envision a world with only rudimentary electronics. --Chuck
Re: Reading MT/ST Tapes
I would think that an engineer would realize that the glass is neither half-full NOR half-empty; it is merely that the glass was spec'ed with the wrong size. Yes, I am too cynical to be in marketing. On Fri, 30 Jul 2021, Mike Stein wrote: And here I've always thought of you as a pessimist who would have called it 'Half Empty ST'... On Fri, Jul 30, 2021 at 9:17 PM Fred Cisin via cctalk wrote: Yep. And, it was not appreciated when I suggested an interim release between the MT/ST emulator and "Full-ST" to be called "Half Full ST" On Fri, 30 Jul 2021, grif...@mindspring.com wrote: Scope Creep.. no telling how many projects died in stalled development. On Jul 30, 2021 16:36, Fred Cisin via cctalk wrote: On Fri, 30 Jul 2021, Chuck Guzis via cctalk wrote: > Not really--it's very old technology, (1964), of limited capacity (about > 20 KB per tape), was a hideously expensive way to buy a typewriter > (about USD$7000 in 1964, or about USD$61,000 today), used almost > exclusively in large corporate offices to create form letters and > documents. In other words, it was not intended as an archival medium. > The effort required in preparing a document was considerable (one used > the mini-keypad for various functions). For a memo, it was easiest to > use the typewriter as a typewriter. > There are more interesting things to look at. Well, form letters are "important". But, once microcomputer word processing matured, they could be done easily and much better. An acquaintance was working on creating an emulation of the MT/ST, as a way for those who were familiar with the MT/ST and/or actually liked it, to be able to continue unchanged on a microcomputer. But, then he started adding features. Besides delaying the completion until it was no longer relevant, it was suggested that he change the name from "MT/ST" (pronounced "empty ST") to "FULL ST".
Re: Reading MT/ST Tapes
And here I've always thought of you as a pessimist who would have called it 'Half Empty ST'... On Fri, Jul 30, 2021 at 9:17 PM Fred Cisin via cctalk wrote: > Yep. > > And, it was not appreciated when I suggested an interim release between > the MT/ST emulator and "Full-ST" to be called "Half Full ST" > > > On Fri, 30 Jul 2021, grif...@mindspring.com wrote: > > > Scope Creep.. no telling how many projects died in stalled development. > > > > On Jul 30, 2021 16:36, Fred Cisin via cctalk > > wrote: > > > > On Fri, 30 Jul 2021, Chuck Guzis via cctalk wrote: > > > Not really--it's very old technology, (1964), of limited > > capacity (about > > > 20 KB per tape), was a hideously expensive way to buy a > > typewriter > > > (about USD$7000 in 1964, or about USD$61,000 today), used > > almost > > > exclusively in large corporate offices to create form > > letters and > > > documents. In other words, it was not intended as an > > archival medium. > > > The effort required in preparing a document was > > considerable (one used > > > the mini-keypad for various functions). For a memo, it was > > easiest to > > > use the typewriter as a typewriter. > > > There are more interesting things to look at. > > > > Well, form letters are "important". > > But, once microcomputer word processing matured, they could > > be done easily > > and much better. > > > > An acquaintance was working on creating an emulation of the > > MT/ST, as a > > way for those who were familiar with the MT/ST and/or > > actually liked it, > > to be able to continue unchanged on a microcomputer. > > > > But, then he started adding features. Besides delaying the > > completion > > until it was no longer relevant, it was suggested that he > > change the name > > from "MT/ST" (pronounced "empty ST") to "FULL ST". >
Re: Reading MT/ST Tapes
On 2021-07-30 9:39 p.m., Chuck Guzis via cctalk wrote: One of the shortcomings of the MT/ST when compared to word processors is the lack of a good "mailmerge" option. You could code a stop code on the tape, where the typewriter would allow for manual fill-in-the-blanks operation, but that gets pretty cumbersome when dealing with hundreds of copies. Superseded by the MC/ST system, the "mag card" Selectric in 1969. Far more convenient and better integrated into the typewriter itself (no separate keypad). The MC/ST II in 1973 introduced the ability to "batch" up to 50 cards. Here's a promo film from the period, narrated by the guy driving his road yacht with the AM radio and chatting about it. https://youtu.be/bW_jJjUarp0 --Chuck The MT/ST did pretty good for being a electro-mechanical device,all the logic was relays in it. I seem to recall many years ago one of the old OP guys telling me that it write in stripes across the tape. It would have to be some very simple format because it would be hard to have the thing sync on headers with only a little relay logic. The mag card machines had the advantage of by the time it came along electronics was a lot more compact so they could stuff a much more capable controller in the box. Towards the end of the mag card days there was even a machine that had a daisy wheel typewriter on it. Paul.
Re: Skew vs. interleave
Same here. I've spent many happy hours in 'the good old days' adjusting 'interleave' of ST512/406 MFM hard disks to find the optimum setting for a particular system/controller but had never even heard the term 'skew' until 5 or 6 years ago while playing with odd format diskettes, and then it was in the track offset sense. So I was surprised that some folks in the S100/CPM world use 'skew' in the interleave sense, apparently because the CP/M documentation used it that way. I'm always surprised how a field so dependent on rigid logical concepts and definitions has so many inconsistencies. Thanks everyone! m On Fri, Jul 30, 2021 at 8:47 PM Paul Koning wrote: > > > > On Jul 30, 2021, at 5:35 PM, Mike Stein via cctalk < > cctalk@classiccmp.org> wrote: > > > > There's a small discussion on S100computers about the terms 'skew' and > > 'interleave'. > > > > In CP/M documentation 'skew' refers to what's usually called interleave > > these days, i.e. offsetting sectors on a track to compensate for the fact > > that by the time the computer has processed a given sector the next one > has > > already passed by, so that the computer has to wait an entire revolution > > for it to pass by the head again; in other documentation as in Chuck's > > 22disk for example this is also called 'interleave'. > > > > However, in later documentation the meaning of 'skew' seems to have > changed > > to refer to the offset of sectors between adjacent tracks to compensate > for > > the time required to step the head. > > I've only ever seen the term "skew" with that second meaning. The first > thing you mentioned in my experience is always called "interleave". For > example, the DEC RX50 has 2:1 interleave and 3 sector skew. > > Interleave is normally written as the physical sector number difference of > two logically adjacent sectors (so 2:1 means there is one other sector > between logical sector 0 and logical sector 1). In one place (David > Gesswein's MFM emulator) I've seen it used the other way around, n:1 > meaning that logical sector n is physically immediately after logical > sector 0. > > paul > > >
Re: Reading MT/ST Tapes
Yep. And, it was not appreciated when I suggested an interim release between the MT/ST emulator and "Full-ST" to be called "Half Full ST" On Fri, 30 Jul 2021, grif...@mindspring.com wrote: Scope Creep.. no telling how many projects died in stalled development. On Jul 30, 2021 16:36, Fred Cisin via cctalk wrote: On Fri, 30 Jul 2021, Chuck Guzis via cctalk wrote: > Not really--it's very old technology, (1964), of limited capacity (about > 20 KB per tape), was a hideously expensive way to buy a typewriter > (about USD$7000 in 1964, or about USD$61,000 today), used almost > exclusively in large corporate offices to create form letters and > documents. In other words, it was not intended as an archival medium. > The effort required in preparing a document was considerable (one used > the mini-keypad for various functions). For a memo, it was easiest to > use the typewriter as a typewriter. > There are more interesting things to look at. Well, form letters are "important". But, once microcomputer word processing matured, they could be done easily and much better. An acquaintance was working on creating an emulation of the MT/ST, as a way for those who were familiar with the MT/ST and/or actually liked it, to be able to continue unchanged on a microcomputer. But, then he started adding features. Besides delaying the completion until it was no longer relevant, it was suggested that he change the name from "MT/ST" (pronounced "empty ST") to "FULL ST".
Re: Skew vs. interleave
> On Jul 30, 2021, at 5:35 PM, Mike Stein via cctalk > wrote: > > There's a small discussion on S100computers about the terms 'skew' and > 'interleave'. > > In CP/M documentation 'skew' refers to what's usually called interleave > these days, i.e. offsetting sectors on a track to compensate for the fact > that by the time the computer has processed a given sector the next one has > already passed by, so that the computer has to wait an entire revolution > for it to pass by the head again; in other documentation as in Chuck's > 22disk for example this is also called 'interleave'. > > However, in later documentation the meaning of 'skew' seems to have changed > to refer to the offset of sectors between adjacent tracks to compensate for > the time required to step the head. I've only ever seen the term "skew" with that second meaning. The first thing you mentioned in my experience is always called "interleave". For example, the DEC RX50 has 2:1 interleave and 3 sector skew. Interleave is normally written as the physical sector number difference of two logically adjacent sectors (so 2:1 means there is one other sector between logical sector 0 and logical sector 1). In one place (David Gesswein's MFM emulator) I've seen it used the other way around, n:1 meaning that logical sector n is physically immediately after logical sector 0. paul
Re: Reading MT/ST Tapes
On 7/30/21 4:36 PM, Fred Cisin via cctalk wrote: > Well, form letters are "important". > But, once microcomputer word processing matured, they could be done > easily and much better. > > An acquaintance was working on creating an emulation of the MT/ST, as a > way for those who were familiar with the MT/ST and/or actually liked it, > to be able to continue unchanged on a microcomputer. > > But, then he started adding features. Besides delaying the completion > until it was no longer relevant, it was suggested that he change the > name from "MT/ST" (pronounced "empty ST") to "FULL ST". One of the shortcomings of the MT/ST when compared to word processors is the lack of a good "mailmerge" option. You could code a stop code on the tape, where the typewriter would allow for manual fill-in-the-blanks operation, but that gets pretty cumbersome when dealing with hundreds of copies. Superseded by the MC/ST system, the "mag card" Selectric in 1969. Far more convenient and better integrated into the typewriter itself (no separate keypad). The MC/ST II in 1973 introduced the ability to "batch" up to 50 cards. Here's a promo film from the period, narrated by the guy driving his road yacht with the AM radio and chatting about it. https://youtu.be/bW_jJjUarp0 --Chuck
Re: Reading MT/ST Tapes
On Fri, 30 Jul 2021, Chuck Guzis via cctalk wrote: Not really--it's very old technology, (1964), of limited capacity (about 20 KB per tape), was a hideously expensive way to buy a typewriter (about USD$7000 in 1964, or about USD$61,000 today), used almost exclusively in large corporate offices to create form letters and documents. In other words, it was not intended as an archival medium. The effort required in preparing a document was considerable (one used the mini-keypad for various functions). For a memo, it was easiest to use the typewriter as a typewriter. There are more interesting things to look at. Well, form letters are "important". But, once microcomputer word processing matured, they could be done easily and much better. An acquaintance was working on creating an emulation of the MT/ST, as a way for those who were familiar with the MT/ST and/or actually liked it, to be able to continue unchanged on a microcomputer. But, then he started adding features. Besides delaying the completion until it was no longer relevant, it was suggested that he change the name from "MT/ST" (pronounced "empty ST") to "FULL ST".
Re: Reading MT/ST Tapes
On 7/30/21 3:56 PM, Cory Heisterkamp via cctalk wrote: > With all of the pet projects documented on the net (ranging from the esoteric > to the absurd) it’s interesting that no one has tackled this one yet. -C Not really--it's very old technology, (1964), of limited capacity (about 20 KB per tape), was a hideously expensive way to buy a typewriter (about USD$7000 in 1964, or about USD$61,000 today), used almost exclusively in large corporate offices to create form letters and documents. In other words, it was not intended as an archival medium. The effort required in preparing a document was considerable (one used the mini-keypad for various functions). For a memo, it was easiest to use the typewriter as a typewriter. There are more interesting things to look at. --Chuck
Re: Skew vs. interleave
On 7/30/21 2:35 PM, Mike Stein via cctalk wrote: > There's a small discussion on S100computers about the terms 'skew' and > 'interleave'. > > In CP/M documentation 'skew' refers to what's usually called interleave > these days, i.e. offsetting sectors on a track to compensate for the fact > that by the time the computer has processed a given sector the next one has > already passed by, so that the computer has to wait an entire revolution > for it to pass by the head again; in other documentation as in Chuck's > 22disk for example this is also called 'interleave'. > > However, in later documentation the meaning of 'skew' seems to have changed > to refer to the offset of sectors between adjacent tracks to compensate for > the time required to step the head. > > Can anyone (Fred, Chuck?) shed some light on this apparent double meaning > of 'skew'? And if skew was used to describe sector interleave then what was > the offsetting of sectors between tracks called? The CP/M definition of "skew" was the first time I'd ever heard of using it in that manner. 22Disk's use of "SKEW" was a late cop-out for formatting only. I probably should have used the word INTERLEAVE, but that had already been used in the documentation. I ran out of synonyms. In any case, unless you're formatting floppies, the keyword doesn't matter--and in fact, is omitted for most of them. Mea maxima culpa. The term "interleave" perfectly describes the mechanism. At a 3:1 interleave, reading sectors consecutively takes three revolutions, as the sectors for each revolution are *interleaved* with those of the other two revolution. "Skew", or offsetting the start of a track perfectly corresponds to the dictionary definition of (noun) "slant" or "bias", which is what it is--the track organization is the same as the previous and following tracks, but it's rotated/slanted with respect to the previous and succeeding tracks. Think of it this way, you have a stack of cardboard discs whose faces are divided into numbered segment. With the discs stacked up, draw a vertical line on the side of the stack from top to bottom. Now rotate each disc slightly with respect its predecessor, such that the outside vertical line looks slanted or twisted. Hence "skew". I've run into formats where "skew" differs not only from side-to-side, but also differently from cylinder-to-cylinder. In magnetic tape, "skew" refers to the relative misalignment of bit cells in a given frame. Lots of attention is paid to "deskewing" hardware. --Chuck
Re: Skew vs. interleave
On Fri, 30 Jul 2021, Mike Stein via cctalk wrote: There's a small discussion on S100computers about the terms 'skew' and 'interleave'. In CP/M documentation 'skew' refers to what's usually called interleave these days, i.e. offsetting sectors on a track to compensate for the fact that by the time the computer has processed a given sector the next one has already passed by, so that the computer has to wait an entire revolution for it to pass by the head again; in other documentation as in Chuck's 22disk for example this is also called 'interleave'. However, in later documentation the meaning of 'skew' seems to have changed to refer to the offset of sectors between adjacent tracks to compensate for the time required to step the head. Can anyone (Fred, Chuck?) shed some light on this apparent double meaning of 'skew'? And if skew was used to describe sector interleave then what was the offsetting of sectors between tracks called? Inquiring minds need to know ;-) Good question. You obviously understand the issue, but others might not. So, here is the background: It is not the only item where each company has their own name. What to "granule", "block", "allocation unit" have in common? How can they get away with making up their own names for everything? MS-DOS has a "File Allocation Table" that consists of a linked list of 12 bit entries. Not all are 12 bit. What is it called on Coco? Mac? "Microsoft Stand-Alone BASIC"? When reading multiple sectors, after reading one sector, and going back for the next one, a fast system can then read the next one, but, if it takes too long to process before reading again, the beginning of the next sector may have already gone by, and you have to wait a full revolution of the disk before you can get it. On a 300RPM disk, a revolution is 200 ms. (1/300 of a minute) On a 360RPM disk (1.2M and 8"), a revolution is 167ms (1/36 of a minute) That's enough of a delay to want to do something about it. Other than making the whole system faster, a simple solution is to rearrange the sectors. Instead of 1 2 3 4 5 if the sectors were stored on the disk as 1 4 2 5 3 or even 1 5 4 3 2 then when going back for the next sector, you would wait part of a revolution, instead of the whole revolution. Some called that "skew", some called it "interleave", some called it "sector sequence". It is a physical interleaving of the sectors. It only requires that FORMAT put them on the disk in a different sequence (trivially easy). For reading and writing, it doesn't matter, and can be ignored, since your BIOS or FDC read will look for sector #1, then #1, then #3, ... and will wait patiently until the sector with the right "header" comes around But, there is another related way to do the same thing. Instead of rearranging the physical sequence of the sectors, use them in a different order. With the physical sectors still in order of 1 2 3 4 5 When writing a file, you could put the first data in sector 1, then put the next data in sector 3, then 5, then 2, then 4. That is called "logical interleave" It does mean that the software that reads the file needs to know to read 1 3 5 2 4 , and then assemble the file accordingly. If you have an "alien" disk, that you are not yet familiar with, and the sectors are in non-sequential order, then it probably uses a physical interleave, and your software can go ahead and read a 1 2 3 4 5 sequence. But, if the sectors on the disk are in 1 2 3 4 5 order, then, is it assuming that you can read that fast? or that you don't mind waiting a full revolution between sector reads? OR is it using the sectors in a "logical interleave" sequence? Well, you could read the file, and see whether it makes sense. Or, find a file on the disk that is text, a programming source file, or something else that you are familiar with, such as sequential data. Read a sector, and look for text at the end of the sector, particularly incomplete word, then look at the other sectors to see which sector has the rest of that word (called, "looking for half a worm"). Sometimes, you may need to do a lot of that to find the sequence. OK, that was "Interleave", which used to occasionally be called "skew". But, there is another use of the word "skew". Later on, after the interleave was "solved", people looked for other ways to avoid wasted time. When you finish reading a track, and step to the next track, will you ba able to read in time for the first sector? Or will you have to wait an entire revolution for it to come around again? To speed that up, some systems start each track at a different point: 1 2 3 4 5 2 3 4 5 1 3 4 5 1 2 4 5 1 2 3 5 1 2 3 4 1 2 3 4 5 For reading or writing, it doesn't matter, since your BIOS or FDC read looks for a sector number and doesn't care about order. For FORMAT, it means a different sector sequence on each track. So, we have two concepts, and two words, and inconsistent choices of the words. One way to thi
Re: Reading MT/ST Tapes
> On Jul 29, 2021, at 12:46 PM, Chuck Guzis via cctalk > wrote: > > A link I forgot to include that gives a flavor of how the tapes are used: > > https://files.eric.ed.gov/fulltext/ED112083.pdf > > Curious thing is that was no take-up reel on the MT/ST; the 100 feet of > tape simply was ejected loose and later rewound back into the cartridge. > > > --Chuck All, thanks for the references and background. I guess the first hurdle for the library is if there’s even data present. I passed on the suggestion of liquid mag developer as something “easy” to try. With all of the pet projects documented on the net (ranging from the esoteric to the absurd) it’s interesting that no one has tackled this one yet. -C
Skew vs. interleave
There's a small discussion on S100computers about the terms 'skew' and 'interleave'. In CP/M documentation 'skew' refers to what's usually called interleave these days, i.e. offsetting sectors on a track to compensate for the fact that by the time the computer has processed a given sector the next one has already passed by, so that the computer has to wait an entire revolution for it to pass by the head again; in other documentation as in Chuck's 22disk for example this is also called 'interleave'. However, in later documentation the meaning of 'skew' seems to have changed to refer to the offset of sectors between adjacent tracks to compensate for the time required to step the head. Can anyone (Fred, Chuck?) shed some light on this apparent double meaning of 'skew'? And if skew was used to describe sector interleave then what was the offsetting of sectors between tracks called? Inquiring minds need to know ;-) m
Help reading a 9 track tape
Hi, I have been lurking for a few years, but thought I'd finally speak up as I just received a 9 track tape purportedly containing the source code to Schoonschip (https://en.wikipedia.org/wiki/Schoonschip). This is a 2400' reel recorded at 1600 bpi based on the labels, and a cursory examination suggests that it is still in pretty good shape (although I am not sure how it was stored over the years). Here is a picture of the tape: https://drive.google.com/file/d/1JgY8QdVDchxubUz39jYn86gEczSvFhcZ/view?usp=sharing We no longer have any equipment that can read the tape, so I was wondering if anyone may be willing to help or if anyone had suggestions on where to go to get it read. Thanks! - jim -- James T. Liu, Professor of Physics 3409 Randall Laboratory, 450 Church Street, Ann Arbor, MI 48109-1040 Tel: 734 763-4314Fax: 734 763-2213Email: jim...@umich.edu
