S100 Computers

by bilegeek • 5 years ago

134 55 5 years ago

gumby• 5 years ago

My first machine as a mad 14 year old was an S-100 system I build from bare board kits and programmed (initially) from a front panel I designed. My dad eventually took pity on me and got me a serial terminal.

I had a Z80 CPU that could handle a blazing 2 MHz IIRC but I remember I could never run at that speed, though I could do more than 1 MHz if I disconnected my front panel.

sliken• 5 years ago

Heh, I had a IMSAI 8080, pretty sure it has a S100 interface for add in cards. I started with a paper based terminal then upgraded to the Hazeltine 1410 I think it was. Amusingly the paper based system (teletype) was 110 baud, but had flair/drama. I remember playing star trek and listening for each position that was a "." for empty space or ** for an enemy.

Playing the same game at 300 baud on the hazeltine 1410 was pretty boring in comparison.

mulmen2• 5 years ago

I love this stuff. My current side/evening project is the Ben Eater 8-bit breadboard CPU. My long term vision is to transfer it to S-100 boards.

amock• 5 years ago

If you're interested in things like this then https://odysee.com/@JamesSharman:b (or https://www.youtube.com/user/weirdboyjim) is another channel you might find interesting.

mulmen2• 5 years ago

Thanks I will check those out!

I have seen the pipelined CPU video, very cool! Part of why I want to build on a S-100 platform is so I can make architectural changes like that.

The possibilities are endless.

bryanlarsen3• 5 years ago

IMO S100 is under-represented in the history of microcomputers. That history is usually represented as Apple, Tandy, Commodore and Atari vs IBM PC & clones. But in my opinion, the IBM PC & clone / MS-DOS ecosystem is a fairly direct successor of the S100+CP/M ecosystem.

tenebrisalietum2• 5 years ago

Well ...

The "motherboard" of most S100 systems AFAIK were simply a a power supply and bunch of slots. Nothing onboard, your RAM fit in a slot, your CPU card fit in a slot, your video card or serial port for your terminal fit in a slot, your disk controller fit in a slot, etc.

The original IBM 5150 had RAM and CPU onboard, as well as a tape I/O port.

I did run into an old Zenith PC clone at a Goodwill a while back. I think dated from 1987.

Really weird system - the motherboard was an S100-style backplane that only had the Motorola MCxxx-whatever clock chip (a real one and even socketed). On a big ISA-style card was a 286 with a lot of other chips, another big ISA-style card that looked like RAM, and a third that had all the discrete components of your PC chipset - the PIT, the two UART chips, the two DMA controllers. I forget if the PICs were there or on the CPU board.

The BIOS was also weird ... had a built in monitor complete with assembler and disassembler commands.

Every single chip was socketed. It was ... bizarre. Had an MFM drive running DOS 2-point-something and an ISA VGA card in one of the slots. Still worked.

jacquesm6• 5 years ago

It's called a backplane.

kevin_thibedeau• 5 years ago

Apple IIs had a (mostly) backplane architecture. It wasn't an uncommon thing.

tyingq2• 5 years ago

Sounds like the Z-286. The US Air Force bought lots of these.

A diagram that shows the backplane: https://arvutimuuseum.ee/th99/m/U-Z/34130.htm

Sales brochure: https://www.1000bit.it/js/web/viewer.html?file=%2Fad%2Fbro%2...

bryanlarsen3• 5 years ago

Not all systems were like that, some were more like the 5150. Here's one: http://www.s100computers.com/Hardware%20Folder/HeathZenith/M...

ddingus3• 5 years ago

Seems much closer to an Apple 2 than S100 type systems.

ddingus3• 5 years ago

From a hardware POV. In software, I agree. Should have been clear.

msla• 5 years ago

I agree the history is biased towards the more mainstream home systems, as opposed to the sized-down business systems, which is what the S-100 computers amounted to.

In fact, the distinction between "home" system (a mostly non-extensible computer in a plastic case with a ROM BASIC as an OS and a focus on graphical games and edutainment) and "business" system (an extensible, if not a kit, system in a metal case with CP/M or MP/M as an OS and a focus on business software) is lost, even in the histories.

rootbear4• 5 years ago

My first job out of college was at Scion Corporation, who made the MicroAngelo S-100 graphics boards. I did Z80 programming for the firmware. They were nice boards but very expensive so I never got one for myself. The company nearly died when their follow on board for the IBM-PC was a failure, but that's a longer story.

jeffbarr• 5 years ago

Was that in / near the University of Maryland in the late 1970's? I was working at a computer store in Rockville as a teenager. Chuck Rieger came in and showed me and the other employees the MicroAngelo. It seemed to be very expensive and very complex, if memory serves me right.

rootbear4• 5 years ago

Scion was in Reston, Virginia, but Chuck was a professor at the University of Maryland as well. He eventually quit UMD to work at Scion full time. He's the reason I got the job, he was one of my UMD profs. The MicroAngelo was easy to program but expensive because it was basically a full computer. It had an onboard Z80 and 32K (later 64K) of RAM. I worked there from 1981 to 1983-ish, when they fell on hard times and had to lay a bunch of people off.

jacquesm6• 5 years ago

There's a name I haven't heard in a couple of decades. Those neurons shed some rust when they activated :)

rootbear4• 5 years ago

I know the feeling!

garyrob• 5 years ago

I had a Gifford S100 system running Concurrent CP/M and with telephone-voice interface boards that ran a voice-based dating site I designed and programmed in Pascal. The CPU was a 286 running at 8mhz. It was in NYC, with phone number 212-ROMANCE.

vile_wretch• 5 years ago

A Sol-20 with monitor sold at an estate auction near me for so cheap not too long ago. I had no idea what it was and had my eye on the Apple IIc instead. I did end up winning a box of S100 bus cards and Sol-20 tapes though, including a "Micro Soft" extended basic cassette. The lot I won also came with an S100 bus "music synthesizer board" which is pretty awesome. I ended up selling most of it off to fund my stupid Vintage Apple collection though.

Wistar• 5 years ago

Not super S100 focused but, in the early 80s, I used an Alpha Microsystems S100 multi-user system with a WD16 processor. Later, the company I worked for, a video production company, upgraded to the 68000 based Alpha Micro. The whole company ran on that thing, accounting, writing and I even wrote a small program allowing it to control a Chyron Scribe video character generator in the edit suite.

I remember liking the system very much but admit that I didn't have much with which to compare it. I thought their OS, AMOS and AMOS/L, was great.

Someone I know who knew Bill Gates fairly well at that time told me that Alpha Microsystems was a company that truly scared Gates.

In 1986, I met Dick Wilcox, one of the Alpha Microsystem founders as he was buying a Pitts S2B at the Auburn, WA airport.

skissane2• 5 years ago

There's an open source emulator for the WD16-based Alpha Microsystems: http://www.kicksfortso.com/Am100/

Not for 68K-based though. Alpha Micro appears concerned that allowing an emulator for that might harm their business: http://kicksfortso.com/am100pdf/alex.pdf

That was almost 20 years ago now, I don't know how much of their business actually survives. They have a website live still, but it seems quite non-functional: http://www.alphamicro.com/

It appears AlphaMicro have their own commercial/proprietary emulator for their 68K systems: http://www.alphamicro.com/ampm/8kfaq.htm

technothrasher• 5 years ago

I spent many hours coding purchasing and inventory systems for our company in the late 80's on our AM-100/L.

I tried to get it working again just for fun in the early 2000's but it had some hardware issue and Alpha Micro was less than enthusiastically interested in helping me with technical information. Ah well.

It's still sitting in a storage room to this day. Probably hopelessly defunct, but I just can't bring myself to get rid of it.

jefurii• 5 years ago

I wish there was a modern version of the S-100 bus. I don't have a use case but I've always thought that form-factor was really cool.

jacquesm6• 5 years ago

In industrial applications there are still plenty of systems built on good old ISA and PCI buses with the host on one card and a whole pile of IO of all kinds of plumage on others.

pezezin3• 5 years ago

Don't forget good ol' VME.

PAPPPmAc• 5 years ago

I'm not sure if it's what you mean, but the RC2014 ecosystem ( https://rc2014.co.uk/ ) is a modern-retro design fairly heavily inspired by S100 systems. It's a backplane + boards Z80 system (...with a few other CPU boards made for it) intended for modern hobbyists. Little bit expensive because it's boutique (Minimal system is about $100, a big nice CP/M box with good I/O would be $300ish). I haven't had the disposable time and money for one, but they look like good fun, and honestly pretty easy and cheap compared to real period equipment these days.

stevekemp• 5 years ago

I've long been interested in that particular project; but as you say it is just that little bit too expensive.

So instead of spending the money I've been spending my time, making something similar (but much much simpler). I'm having fun, even with just a clock, Z80, and EEPROM. My next step will be handle I/O with a keyboard and LCD, hopefully by the end of the month.

mikewarot• 5 years ago

My late friend, Lloyd Smith used offer a service where he split the DC power bus and added a second power supply to S-100 systems, because the stock power supplies were undersized for a full card cage.

CarVac• 5 years ago

My dad has an IMSAI 8080. It's a gorgeous piece of hardware, with the multicolored switches on that dark plastic panel.

He showed me how to write basic programs on it once in assembly, but never much more than that.

musicale• 5 years ago

It's interesting to imagine an alternate world of CP/M-86/S-100 vs. MS-DOS/ISA for x86 PCs.

The brilliant bit to me is how modular S-100 seems to be with everything on a swappable card. This seems to enable a more granular upgrade and system build approach compared to what we have with modern PCs where most core components are stuck on a single motherboard.

I think I might be interested in a modular, semi-disaggregated PC based on a PCI backplane.

skissane2• 5 years ago

This seems to enable a more granular upgrade and system build approach compared to what we have with modern PCs where most core components are stuck on a single motherboard.

You end up paying for that increased flexibility in a number of ways: greater physical size, increased part count, increased manufacturing costs. I think even if the industry went with CP/M-86/S-100 instead of MS-DOS/ISA, sooner or later people would have put the CPU card and the backplane on the same PCB, and we would have ended up in more or less the same place – the cost advantages of doing so would have made that development inevitable.

I think I might be interested in a modular, semi-disaggregated PC based on a PCI backplane.

You can buy those, they exist – there are passive PCI backplanes [0] into which you can plug a CPU card. They are used for industrial control applications. You are going to pay a premium for that though. As well as increased number of parts/etc, the lower volumes they are manufactured in adds to the cost.

[0] https://www.advantech.com/products/passive-backplanes/sub_1-...

tssva2• 5 years ago

Some early PC compatibles were based upon the same backplane/card approach as the S-100 computers. I have a Zenith/Heathkit Z-160 transportable in my collection. It has an 8 slot 8-bit ISA backplane and everything including the cpu is on ISA cards. This backplane is shared with the Zenith/Heathkit Z-150 desktop. They also released AT class desktops, by this time the portable PC form factor had become too small to support this approach, which used a 16-bit ISA backplane before eventually abandoning the approach for their later computers. Most likely for all the reasons you point put.

analog31• 5 years ago

I was actually doing computer repair when the IBM PC came out. It had a backplane, but most of the system was on the motherboard. Repair people were horrified that many if not most of the logic chips were soldered in, not in sockets like the Apple II. At the time, I had repaired Apple II's, and dumb terminals that had soldered IC's. Half of my time was spent painstakingly de-soldering chips from boards so a replacement chip could (hopefully) solve the problem.

On the other hand, most Apple II repairs consisted of what we jokingly called "the laying on of hands," which meant reaching in and pushing all of the chips back into the sockets with the palms of your hands. That was always accompanied by rubbing the gold fingers on the disk controller card with a pencil eraser because the gold plating was inferior. Many Apple II repairs were 5 minutes. Third on the list was power supplies, which we never figured out how to repair at a component level, and were justifiably afraid of.

At the time, IBM published some data based on their own years of computer service. They serviced a lot of their own boards, and made their own memory chips. Their data showed that chips were actually more reliable than sockets, so they limited sockets to those which had potential for fallout in production (the 8088), and the memory chips which were an optional add-on. And the ROMs, which could potentially be upgraded.

thoughtsimple• 5 years ago

S100 was also a widely used industrial bus. My first job out of college (1980s) was writing software for a machine tool where the controller was a custom s100 80186 motherboard and a bunch of ROM and static RAM s100 boards. We used a ton of static RAM (probably 4-6 64k boards, I can't remember exactly) that were battery backed up. You could power cycle the controller and just start back where you left off.

salgernon• 5 years ago

Sadly, Bill Godbout (mentioned) lost his life in the 2018 California wildfires.[1][2]

[1] https://www.theregister.com/2018/11/18/bill_godbout_obituary [2] https://news.ycombinator.com/item?id=18445340

emptybits• 5 years ago

An adjacent rabbit hole I'd recommend ... (functional but decidedly retro nav on that site)

https://www.retrobrewcomputers.org

Besides S100 you'll find there, the Eurocard Bus which is also long-lived and flexible.

https://www.retrobrewcomputers.org/doku.php?id=boards:ecb:st...

zeckalpha• 5 years ago

Another fun modular bus: https://en.m.wikipedia.org/wiki/PC/104

car• 5 years ago

I remember seeing an Altair 8800 next to a "Gandalf" at WeirdStuff in Sunnyvale, a few years before they closed for good. Had no idea what these were.

phaedrus• 5 years ago

My mentor worked with drone projects in the early 80s. They flew S100 bus computers. The drone craft were at least half the size of an ultralight manned airplane.

anonymousiam• 5 years ago

I regret giving away my IMSAI 8080 S-100 box a little over 15 years ago. I should have looked on eBay. If I had, I would have known how collectable they are. I may have been able to get a few hundred bucks for it anyway. It was still in working condition, but all of my (8") boot disks were destroyed by humidity. It booted a few times, but then didn't. While troubleshooting, the disk drive ate all the remaining boot disks.

S100 Computers

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