Thoughts on minicomputer to microcomputer transition (PDP to Macintosh)

[voidstar78]

Chuck, those sounds like things Joe MacMillan would do (character from "Halt and Catch Fire"). Another story I recall - although not nearly as sinister -- but the "SX" CPUs in the 1990s? (I think that's how they were designated) Weren't those degraded or "rejected" DX versions of chips? Like 386DX vs 386SX. Something about the edges of the wafer as they were being produced, made them less capable processors and were sold at a discount (odd since if it was "edge defects", it would be less supply of those?).


Here's another updated V3 of this "mural", which I have a question below maybe ya'll can help:




- Added PC-5000 from Sharp. Not that this was the first "PC-typewriter" with a DOS in a ROM - but the PC-5000 was one of the early attempts, showing how quickly the industry ventured into "laptop computing" to use while on travel. But mainly the interesting thing to me about the PC-5000 was the attempt at using Bubble Memory - which I never quite understood much about (but apparently it wasn't faster or more reliable, nor cheaper). Anyhow, the transition from "luggables" to "laptops" is noteworthy. [ anyone know which laptop was first to have 2 hour battery, enough to last on a flight? the PC-5000 didn't yet have a battery ]

- Added COMMBAT :D Someday I'd like to see a WiModem used for some cross-platform vintage gaming. I understand why that wasn't viable in the early 1980s (even if the game existed, you didn't have anyone to connect to - or didn't have two phone lines - and developers didn't have the tools yet to easily make such software). But now with cc65 and modern development tools, we just need to get an API/SDK for the WiModem (maybe that will come about when the X16 rolls out).


What I need help with is, along the top... I added tape and disk. I know N-track tape (7-track, 9-track) was way earlier than 1970, my point is the DEC systems of 1970 still used those. Then there was the DC300 tape, which I'm not sure if it's accurate/fair to call that a reel-to-reel in miniature? (I only used a 9-track tape; did those have BOT/EOT marker holes?)

My question is, did the DEC paper tape come before 9-track? I think so, since in the PDP-1 manual I think it had an image of the paper-tape reader as a standard part of the system (as early as 1960). Did IBM do 9-track tape first, around 1965?

But then the 8" floppy and DC300 tape, those were around 1972, correct? The DC300 depends on a constantly spinning belt, which just seems very inefficient (will wear out and waste energy when not using it). But in those days, if you're bothering to power on the machine, you're probably heavily using it (and saving or loading something to/from the memory space), so maybe there wasn't that much idle time. Still, seems the IBM 5100 with the DC300 tape should have had an extra switch to power down the tape drive when not in heavy use. [ were the DEC's powered up for the day? for the week? or 24/7? or it just varied? ]

Was "rolled" paper-tape referred to anything differently, than the older "flat" paper-tape? Like if I needed to order some rolled paper-tape (instead of "flat" paper-tape), what would I go order from the store or catalog? I never had the honor of using punched tape :D

I'm not sure who first stored digital data on an audio tape. I recall reading about Chuck Peddle helping to perfect the timing on that when preparing the ROM for the PET. Obviously the concept came earlier, but who applied it to the standard audio media?

And I realize the 5.25" was closer to 1976. I still put it closer to 1980, as that's when they were more reliable and people could actually afford them (the Model 3's disk drive was around $850).

 

[krebizfan]

I think the Kaypro had a battery pack that could be installed. I don't know the usage time of that. Tandy 100 (and all the related models) tends to win accolades as the design that lasted many hours between replacing batteries. LCD and CMOS were major miracles. Otherwise identical calculators achieved 25 fold increases in battery duration thanks to those.

Bubble memory could survive shock and other hazards including radiation nicely. Speed was poor; the capacities never reached expected levels.

There was rolled (dry and oiled) and fanfold (used by DEC high speed punches/readers) punched paper tape. Probably other variations since it was about a century old when computers started using it. Other than making used 35mm film plastic cases very popular since they made great storage for paper tape, I don't remember trivia about them.

1972 is listed as when RCA had a cassette interface for what eventually became the COSMAC ELF. 1975 had multiple articles describing variations on the concept of sound generation for use with a standard cassette deck. There were other systems before 1975 with cassette derived storage but I don't know the specifics of how data was stored. See the HP9821 or IBM SCAMP for examples. I think MCM was digital.

 

[g4ugm]

Why obscure machines like the coleco and sharp, but no Atari ST or Commodore Amiga? I guess that as 1985 machines they don't fit on your time line but they, and i guess the 60k unix workstations and PC/AT were what brought mini power to the desktop, not the IBM PC.

 

[Chuck(G)]

My question is, did the DEC paper tape come before 9-track? I think so, since in the PDP-1 manual I think it had an image of the paper-tape reader as a standard part of the system (as early as 1960). Did IBM do 9-track tape first, around 1965?

But then the 8" floppy and DC300 tape, those were around 1972, correct? The DC300 depends on a constantly spinning belt, which just seems very inefficient (will wear out and waste energy when not using it). But in those days, if you're bothering to power on the machine, you're probably heavily using it (and saving or loading something to/from the memory space), so maybe there wasn't that much idle time. Still, seems the IBM 5100 with the DC300 tape should have had an extra switch to power down the tape drive when not in heavy use. [ were the DEC's powered up for the day? for the week? or 24/7? or it just varied?

Wow, too much to go into detail in a single post. I suggest some research on your part, but I'll offer the following:

Paper tape, like punched card, is a write-once medium and predates computers.
The Digital cartridge belt is somewhat flexible and also has a certain amount of "slip" built in. The idea is that it maintains the tape tension while the tape is moving--it solves the issue of maintaining separate feed and takeup mechanisms. The belt moves only when the tape does. Unfortunately, TPU is not the most stable of polymers and eventually the belt degrades chemically (chemical bonds deteriorate) and the belt either loosens excessively or just breaks. There is no single scheme for signalling EOT and BOT--for example, in Iotamat preformatted cartridges, a recorded pattern defines those--there are no optical sensors.
Half-inch open-reel tape uses reflective tape about a quarter-inch wide to signal BOT and EOT. I don't recall what the early metal tapes used on UNIVAC systems used for that, but I'm sure the information is available online.
The big difference between half-inch open-reel tape and cartridge tape is the way the data is recorded. Half-inch tapes use parallel data channels; cartridge tape is bit-serial. Other than the very early models of cartridge tape, data is also recorded in a "serpentine" manner, by repositioning the head and changing the direction of movement.

 

[voidstar78]

Hmm, on commercial flights I don't see anyone ever using a luggable (maybe on private flights using an AC outlet). But true, those PC100 devices were probably used on a flight, bus, or train - not sure if any novels were written on those devices, but probably some editorial updates/organizing thoughts. (speaking of novels, this article has some insights on the first novelist to use a word processor).

I do recall the IBM SCAMP prototype did show a regular audio tape (the later production model used the far faster but bulkier DC300). No idea if that tape was functional or just a prop (in the SCAMP), but the Altair 8800 user manual list "audio cassette record interface" as one of its accessories.


With 2+ million sold, I don't consider the Coleco obscure. But I included it because it shows you had this variety of systems growing like mushrooms all over, they saturated the market (upright pianos had the same market saturation in the 1880s, with plethora of cheaply built pianos - leading to a crash in that market as well). Anyhow, the IBM PC displaced all that, by successfully rallying developers with confidence that it was a system with "staying power."

@g4ugm
Did do you mean PC/AT as in the IBM 5170? I suppose that's fair (in terms of the 80286 somewhat catching up to the capability of the mini's). I stopped at 1984 because I think by then, it was very definitive that useful (to non-engineers) personal computing had arrived, the general "look and feel" of the home/office appliance had been established, and useful software was available (i.e. way beyond programmable calculators). The reason I put a Tandy instead of the 5170 was as a representation of "PC-clones" becoming so prevalent and also that the Tandy 1-up'd the IBM PCjr (but you see basically the same shape, so PC design was then just refinements at that point) - so I wanted something besides another IBM (I think the Tandy stands out because of the 3-voice and early EGA/16-color they had, but true it remains 8088 based). PC-clones happened nearly as soon as the IBM PC came out (thanks to CDP and Compaq), making refinements and helping to keep cost reasonable. Well, what's a non-IBM 80286 desktop clone in 1984?


I do agree the Sharp is pretty obscure. But it ran MS-DOS (in a ROM), which is how it contrast to the earlier PC100, and shows the start of the next phase in micros: desktop PC had been "figured out", now the race was on for true mobile (cordless) computing and what form that would look like. The PC-5000 didn't get it quite right, but neither did the IBM 5100 (screens were too small).


And true, I hadn't considered much about unix workstations. I'm familiar with the SGIs and early Sun Microsystems. But, were those before 1985? And, affordable for home use?

 

[Chuck(G)]

I do recall the IBM SCAMP prototype did show a regular audio tape (the later production model used the far faster but bulkier DC300). No idea if that tape was functional or just a prop (in the SCAMP), but the Altair 8800 user manual list "audio cassette record interface" as one of its accessories.

There were tape units that used the Philips audio cassette in digital mode also. One of the earliest that I remember were the units (e.g. Techtran) that were serial-interface and took the place of paper tape. NCR used the cassettes as well. Some CNC PLC gear also used them (I seem to recall a Mazak tape unit).

Part of my MITS Altair kit was BASIC in both paper tape and audio cassette form. Sadly, I have neither today, having loaned both out and having neither returned.

 

[voidstar78]

Wow, too much to go into detail in a single post. I suggest some research on your part, but I'll offer the following:

Paper tape, like punched card, is a write-once medium and predates computers.

I'm familiar with that history. I meant in the context of the image, is it proper to have the paper-tape listed before the 9-track tape? But you're right, it's not a valid question. I don't think paper tape was used much for storing data, but rather instructions to start some processing (then any meaningful amount of data, like account records, stored on tape).

I see punched-tape as sort of like modern day serial port - not literally, but in that they are used to "bootstrap" embedded processors to initiate loading more extensive processing. But maybe I'm wrong, maybe 100 years ago was some room full of census record data stored on some punched tape :D (akin to those data storage rooms full of 9-track tapes of data)

 

[Chuck(G)]

I'm familiar with that history. I meant in the context of the image, is it proper to have the paper-tape listed before the 9-track tape? But you're right, it's not a valid question. I don't think paper tape was used much for storing data, but rather instructions to start some processing (then any meaningful amount of data, like account records, stored on tape).

That would be a mistaken assumption, I think. Consider FORTRAN compiling on a 1620 equipped with paper tape reader/punch and a console typewriter. The order of events runs like this:
1. Read in the first pass of the compiler (no OS involved on these dinosaurs)
2. Read in your source program.
3. An intermediate tape is punched.
4. Read in pass 2 of the compiler, followed by the tape punched in step 3, followed by your tape of library subroutines.
5. An object tape is punched
6. Read in the object tape for running.
A similar procedure was used with punched-card equipment.
Some people think that disks have always been with us, but that would be a mistake. Even when available in the 1960s, disks were expensive and small. So there were tape operating systems, such as the 7090 FMS/IBSYS. I recall that there was a similar system for S/360 machines.

 

[Eudimorphodon]

Why obscure machines like the coleco and sharp, but no Atari ST or Commodore Amiga? I guess that as 1985 machines they don't fit on your time line but they, and i guess the 60k unix workstations and PC/AT were what brought mini power to the desktop, not the IBM PC.

I will note additionally that the positions of the computers over the labels is... iffy at best. Neither the KIM-1(*) nor the Apple-1 existed as "products" in 1975; even the most optimistic interpretation of Steve Wozniak's rusty memory wouldn't put the first power-up date for the Apple-1 prototype more than a month or two away from the end of 1975 and it wasn't actually on sale until July 1976.

(The KIM-1 was *kind* of a cleaned-up version of a previous computer called the "TIM" which was the development system that was available when the 6502 publicly debuted in September 1975, but it wasn't really a complete product, it was more like a set of instructions for wiring up a 6502 to a pile of MOS support chips, including a combination RAM/ROM/IO chip containing the "TIM" monitor. The "Jolt" single board computer was basically a third-party implementation of TIM and arguably the first "commercial" 6502 product. And one of the only machines you could buy off the shelf in 1975.)

A far, far better (and more accurate) entry than the Apple I for "1975" would be the Sphere 6800 computer, for a multitude of reasons:

• The first ads for it appeared around June 1975 and at least a few people got mostly working units before the end of the year.
• The machine was hugely influential at the time, receiving a lot of coverage/hype in magazines like Radio Electronics and Byte.
• It was *arguably* the first low-cost (arbitrarily setting that bar at "under a thousand dollars") computer that was designed entirely around an integrated video console for user interaction.
• The aforementioned video console was implemented with memory mapped SRAM, making it a direct forerunner to the video systems that shipped on the "1977 Trinity" machines. (The Apple-1's video console is a completely bass-akward shift register dingus that's basically a copy of a 1973-vintage TV Typewriter that only allowed extremely slow serial access.) S-100 (and other bus) video cards similarly based on RAM were showing up in 1975, but it wasn't until very late in 1975 or early '76 that computers truly designed around them started showing up. (PolyMorphic System's Poly-88 is an early example; functionally it's very much like the SOL-20 but the keyboard was wired to the box instead of the computer living inside the keyboard.)

Granted the Sphere ultimately failed on the market but, again, at the time it was a big deal.

 

[Al Kossow]

What I need help with is, along the top... I added tape and disk. I know N-track tape (7-track, 9-track) was way earlier than 1970, my point is the DEC systems of 1970 still used those. Then there was the DC300 tape, which I'm not sure if it's accurate/fair to call that a reel-to-reel in miniature? (I only used a 9-track tape; did those have BOT/EOT marker holes?)

My question is, did the DEC paper tape come before 9-track? I think so, since in the PDP-1 manual I think it had an image of the paper-tape reader as a standard part of the system (as early as 1960). Did IBM do 9-track tape first, around 1965?

But then the 8" floppy and DC300 tape, those were around 1972, correct? The DC300 depends on a constantly spinning belt, which just seems very inefficient (will wear out and waste energy when not using it). But in those days, if you're bothering to power on the machine, you're probably heavily using it (and saving or loading something to/from the memory space), so maybe there wasn't that much idle time. Still, seems the IBM 5100 with the DC300 tape should have had an extra switch to power down the tape drive when not in heavy use. [ were the DEC's powered up for the day? for the week? or 24/7? or it just varied? ]

Was "rolled" paper-tape referred to anything differently, than the older "flat" paper-tape? Like if I needed to order some rolled paper-tape (instead of "flat" paper-tape), what would I go order from the store or catalog? I never had the honor of using punched tape :D

I'm not sure who first stored digital data on an audio tape. I recall reading about Chuck Peddle helping to perfect the timing on that when preparing the ROM for the PET. Obviously the concept came earlier, but who applied it to the standard audio media?

And I realize the 5.25" was closer to 1976. I still put it closer to 1980, as that's when they were more reliable and people could actually afford them (the Model 3's disk drive was around $850).

sigh.. where to start

9-track tape was created for System/360 which adopted an 8 bit character set and popularized 8 bit bytes. 7-track went along with the common use of 6-bit character encodings and blocking data in units of 6 bits

paper tape has varying widths, common 5 6 7 and 8 wide. use of paper tape is as old as computers. it was very common to use teletypes and freiden flexowriters
for paper tape I/O. DEC used off the shelf readers (Digitran) and punches (Teletype BRPE) on the PDP-1

folded tape is called 'fan-fold' It has been out of production for decades. the last users of rolled tape was in the numerical control world. That, too has gone out of production

before scotch invented the digital data cartridge in 1972, digital cassettes were used. the advantage over the cassette was you didn't need three motors (or two if
you used reel servos) on the data cartridge because of the internal belt. the problem is the belts aged badly over time

 

[Al Kossow]

Granted the Sphere ultimately failed on the market but, again, at the time it was a big deal.

There has been a bit of a revival over the past year of interest in the Sphere after a machine was found on the curb in San Fransisco

Sphere Computer Source

A research and documentation project for one of the first microcomputers, the 1975 Sphere 1 from Utah. Resources, Sphere web emulator, and book updates!

sphere.computer

and that I got off my butt and found the software cassettes I've had in storage since Melvin Norell gave them to me in the 00s

 

[Chuck(G)]

I will note additionally that the positions of the computers over the labels is... iffy at best. Neither the KIM-1(*) nor the Apple-1 existed as "products" in 1975; even the most optimistic interpretation of Steve Wozniak's rusty memory wouldn't put the first power-up date for the Apple-1 prototype more than a month or two away from the end of 1975 and it wasn't actually on sale until July 1976.

I think there may have been a few Apple Is sold at the HBCC meetings, but I don't recall when--checking the archives of the newsletters may shed some light.
I do recall that many of the attendees were somewhat "meh" about the announcement as they already had 8080 hardware--a few even had 8008 systems. In fact, from the folks at work, I can't recall a single one who bought an Apple I.
I do recall seeing an early ad for the Apple I with the advertised price of $666.66, but I don't recall when. Perusal of old magazines may put a pin in the earliest date.

 

[stepleton]

#2) would be a neat to have a museum with a "room sized" CPU that you could walk thru, and see Instruction Fetch and execution in action. Perhaps VR will give us something like that in the future.

This exists today! Come to the UK and visit the Centre for Computing History in Cambridge to see the Megaprocessor.

 

[Al Kossow]

100 years ago was some room full of census record data stored on some punched tape

nope

this stuff is computing history 101. try reading a book

 

[stepleton]

The DC300 depends on a constantly spinning belt, which just seems very inefficient (will wear out and waste energy when not using it).

While true for the IBM 5100/5110 mechanism you're familiar with, this isn't always the case. Instead of a clutch engaging a continually-rotating belt-driven spindle, the tape drives in the Tektronix 9050-series graphics machines (which are a bit newer than the 5100) use a variable speed drive that only runs when it wants to move the tape. It's nice because it can fast-forward and rewind faster than the read/write speed, while the 5100 has only one speed in either direction.

I'd bet there were other computers that had similar tape drives, but the 9050-series is one I'm familiar with.

I do recall the IBM SCAMP prototype did show a regular audio tape (the later production model used the far faster but bulkier DC300). No idea if that tape was functional or just a prop (in the SCAMP)

I'm pretty certain this tape mechanism was functional.

 

[Eudimorphodon]

I think there may have been a few Apple Is sold at the HBCC meetings, but I don't recall when--checking the archives of the newsletters may shed some light.
I do recall that many of the attendees were somewhat "meh" about the announcement as they already had 8080 hardware--a few even had 8008 systems. In fact, from the folks at work, I can't recall a single one who bought an Apple I.

Spent a few minutes scanning through The collection of HBCC newsletters at DigiBarn and apparently they were not impressed by the Apple 1; I didn't see a single mention of it, anywhere. I don't think there are any mentions of Steve Wozniak either other than his "Joining the club" note in the April 1975 issue where he says he has a "TVT (TV Typewriter) of my own design". (Which I'm sure was invented by him and him alone and dated back to his time in the womb, don't let anyone give any credit to that Don Lancaster scoundrel...) So far as I can tell the next/only mention of Apple-related stuff is a note in the February 1977 issue that Apple is taking pre-orders for the II. So I guess whatever interest there was in it wasn't enough to make the newsletter.

I do recall seeing an early ad for the Apple I with the advertised price of $666.66, but I don't recall when. Perusal of old magazines may put a pin in the earliest date.

They appeared in several "July 1976" magazines. FWIW, "Apple Computer" was incorporated in April and if "you knew a guy" you probably could have bought one in April through June, but I'm skeptical they sold many if any. Actual published reviews of the system by purchasers... I don't think I've seen one before a September issue of a computer magazine. (Which would of course mean the article was done sometime in August.)

 

[Chuck(G)]

The Apple guys set up just across us (10101) on Bubb Road in Cupertino, just a bit off of DeAnza Blvd. Bubb, at the time, backed out onto the railroad tracks separating Cupertino from Monte Vista, which had a cannery on the other side of the tracks. I don't recall much traffic going on in those buildings. We were next to, IIRC, Nicolet Zeta. This was 1977-78.

 

[voidstar78]

“Fan-tape” thank you, that was the term I was trying to remember. Rolled tape I know goes back decades ( even before player pianos ). I meant to just ask, is it fair to say fan-tape was still actively used in 1970? Were punch cards fairly done by 1970 (at least for new systems post 1970)?

 

[krebizfan]

Fan-fold tape was the default for the PC-04 and PC-05. The PC-04/05 manual on Bitsavers is dated from 1973 so it must still have been common. The PC04 was rated at 300 characters per second which was a nice improvement over the standard 10 characters per second for the normal paper tape reader and even better than a lot of cassette based storage.

Punch cards were still the standard. The election of 1972 was conducted on punch cards in the LA region. Cheap data entry. Punch cards are also faster than cassettes. 800 cards per minute means that completely filled out (80 character) cards would break the 1000 characters per second threshold.

The next step up from paper for DEC was the TU-60 tape streamer, basically a compact cassette mechanism with different read/write head and tape. https://www.pdp-11.nl/peripherals/tape/tu60-info.html DEC also had the low cost DEC Tape II TU-58 using DC-100 cartridges and the later TK-25 using DC-300 cartridges (though capable of storing 61 MB since it arrived in 1984).

 

[voidstar78]

Wasn’t the innovative factor of both the kim-1 and apple-1 was that they were a single board? And to whatever that meant exactly, didn’t that ultimately drive down cost? Or specifically the production cost, so they could scale up to 100,000’s of units? 72-76 was kits and ideas, and how to get the integrated package down from $10k to a more reasonable $1k (such that non-engineers can make use of the system, capable of more than just one application, reliable enough to trust in resuming your work later, and compact enough to haul around).