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Feasbility of buying and owning an S-100 compatible computer?

JNZ

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I bought an Altair Clone from Mike Douglas half a year back, and it's pretty much the coolest (and most fun) computer I've owned. I grew up past the era of these first PCs, my earliest machine being a 286. I've created a collection of computers from the 80s: an Amiga 500 and a pimped out 1200, C64 and C64C, all my old DOS and Windows machines I had growing up, a few TRS-80 100s, and two coworkers recently gave a non-functioning Heathkit H-19 and an Osborne with a box full of software (but which has no raster).

I love owning and using computers that are the real deal, and it bothers me a bit that the Altair Clone is just a PIC24 emulating the real magic.

So, how feasible is it to buy, own, and occasionally operate an S-100 bus computer in 2015? I picture an Altair 8800 or IMSAI 8080, but I don't know the other options. I love the front panel switches and status lights, and ideally I'd have a serial board and a disk controller so I could run CP/M. What I enjoy most is writing and debugging assembly.

What's a reasonable price range, and what are the common pitfalls? Can it be trusted to run for hours at a time? Do these machines only need recapping, or are there more serious issues, like irreplaceable floppy motors failing or necessary controller firmware being unobtainable?

Also, bonus question: has anyone ever made a GPIO S-100 bus board? I make little microcontroller projects and having one of these computers bitbang I2C or just toggle GPIO pins would be the coolest thing.

(Edit: I meant buying and *operating* an S-100 computer, not buying and owning.)
 
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Chuck(G)

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IMSAI, maybe, but Altair didn't exactly make industrial-strength systems. Compupro/Godbout is a good choice in heavy S-100 iron; I use (and still have) an Integrand box--came complete with (now faded) blueprints--there were many others. Exactly what do you propose doing with one, keeping in mind that graphics were a luxury that few systems enjoyed?

Bear in mind that I'm not what you would call a collector...others may have very different opinions.
 

JNZ

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Mostly hooking it up to a serial terminal and programming and debugging assembly on the real hardware. (Though I like to write in a modern editor like vim, then upload the .asm and download the .prn, .hex, and .com, using MITS' programming system II). For example, I'm currently trying to figure out how to use the emulated MITS 88-VI/RTC board in my Altair Clone, which involves lots of rewriting, debugging, and making my program more complicated.

A previous project I had was to monitor a stream of serial data and implement my own simple pattern matching, waiting for an error code to be output. If it found it, my goal was to use RTS/CTS on the 2nd SIO port to trigger a gate on a little board I made that switches a 12 VDC light, indicating that a script on my computer had entered an error state. Silly things like that.

I don't expect an 80 char graphics card or anything, as I've been led to believe they were quite rare on these systems. A serial board and any kind of interesting peripheral would give me some stuff to play with, though. Like I said, the best would be a GPIO board, if such a thing exists.
 

NeXT

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So, how feasible is it to buy, own, and occasionally operate an S-100 bus computer in 2015? I picture an Altair 8800 or IMSAI 8080, but I don't know the other options. I love the front panel switches and status lights, and ideally I'd have a serial board and a disk controller so I could run CP/M. What I enjoy most is writing and debugging assembly.
To answer this question on building a machine specifically, it is expensive.
I've looked into the options initially of building my own S100 machine and the cost for four S100 slots, the pre-etched PCB and a suitable power supply was going to set me back $250 and the PCB was one of those "we'll put you on a list and if we get enough orders we'll make a run and email you" kind of things.
Additionally if I wanted an 8080 CPU, 8K ram, one serial port and one 5.25" single sided floppy controller, expect at least $75 on average a card. There ARE bare PCB's for all of these you can buy but again, you are at the mercy of how long it takes for the guy to fulfull enough orders to run a batch. I have not even gotten into the addition of a front panel or an enclosure either.
Stockly's Altair Kit was expensive for a reason. Pretty much any S100 machine that fits your description on the open market will be at least $1200.

I ended up buying the AltairClone because it answers the question of how to build the front panel and enclosure (and have it look good) but the boards themselves are still the single most expensive components. I've yet to find the people I've been told sell the "S100 cards for a dime a dozen" and I'm starting to believe they do not exist anymore, if ever.

I'm sure if you knew a good board house you could probably get the PCB's made for cheaper than I can find. Most of the famous S100 cards have had their PCB layouts scanned in and uploaded for years but most shops want the layout in a file, not UV etch transparency sheets. You can even find the layout diagrams for the Dazzler in the back of its manual.
 

Chuck(G)

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If you can depart from the idea of an S100 machine, there are several good SBCs and Devkits for the Z80 family--many with expanded capabilities and enough peripherals to challenge you.
 

JNZ

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I'm sure if you knew a good board house you could probably get the PCB's made for cheaper than I can find. Most of the famous S100 cards have had their PCB layouts scanned in and uploaded for years but most shops want the layout in a file, not UV etch transparency sheets. You can even find the layout diagrams for the Dazzler in the back of its manual.

I do schematic capture and PCB layout, and with an existing board for testing and a schematic or high resolution scans it should be possible to create these boards. What's the size of a normal S-100 board, 8" by 5"? A medium run at OSH Park of that size would be $40 for each two-layer PCB, and looking at the ICs for the MITS 2SIO, I have to imagine that apart from the discretes, the ICs (if they're even available) could be $20 or more. There'd be more setup costs for doing a one-off run with possible revisions for mistakes, and I wouldn't have the ability to test the boards.

What are the existing kits you're referring to, where you see wait lists for PCBs?

Is there a market for this? If used boards are $75 to $150, I don't think it's cost effective to make new ones, even just trying to break even. Here's a lot of 5 boards for $100: http://www.ebay.com/itm/Lot-of-5-vi...emco-Vector-/311437549810?hash=item48831fe0f2

I bet it makes more sense to use modern chips to combine as many of the discrete ICs as possible, or even an FPGA, though that takes another set of skills. I bet it'd take a year or two to develop, but it might make sense to have a single S-100 board that just runs an FPGA and can emulate a few boards at once. Again, you'd need an S-100 computer just to be able to buy it, though. Is anyone working on something like this?
 

JNZ

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If you can depart from the idea of an S100 machine, there are several good SBCs and Devkits for the Z80 family--many with expanded capabilities and enough peripherals to challenge you.

That's an interesting idea, I hadn't considered that.
 

NeXT

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Is there a market for this? If used boards are $75 to $150, I don't think it's cost effective to make new ones, even just trying to break even. Here's a lot of 5 boards for $100: http://www.ebay.com/itm/Lot-of-5-vi...emco-Vector-/311437549810?hash=item48831fe0f2

That's an auction with seven days and five bids already on it. I'd take that price with a grain of salt. Just wait until the five second mark and the real horserace begins.

What are the existing kits you're referring to, where you see wait lists for PCBs?
Balmmo. ;)

I bet it makes more sense to use modern chips to combine as many of the discrete ICs as possible, or even an FPGA, though that takes another set of skills. I bet it'd take a year or two to develop, but it might make sense to have a single S-100 board that just runs an FPGA and can emulate a few boards at once. Again, you'd need an S-100 computer just to be able to buy it, though. Is anyone working on something like this?
A few of the new run boards have their designs modified to replace now hard to find IC's with much more modern components but really 7400 logic has not changed much and for the most part we are predating when small shops could afford to make their own custom chips. An FPGA in most instances if total overkill.
As for the production of such a super advanced FPGA driven all-in-one board, there's just enough demand for people to warrant the time and effort to even design the layout. Plus most of the people paying the megabucks these days for S100 are collectors and hobbyists, many of which are in it for the fact that one-peripheral-per-board is a lot easier to troubleshoot than modern nightmares with SMD.


...and frankly, it looks really out of place where you got a giant S100 board but there's two or three tiny chips making up the entire machine. (for example, the Omni USB board) ;)
 
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JNZ

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Haha, that Omni USB board looks like a joke someone would make in Photoshop.
 

MarsMan2020

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There is still an active group of S-100 builders at http://www.s100computers.com/, with a Google Group at https://groups.google.com/forum/#!forum/n8vem-s100. I have a whole stack of boards I need to get built, from an 18-slot motherboard all the way to the 386 CPU, 32MB RAM, and XGA video cards. However, building new boards can be pricey - ~$20+100 for a RAM/EEPROM board+components from Digikey. Individual S-100 connectors for a motherboard can run $4-$10 each.

There are more cost-effective options:
-Single board or two-board-stack computers like Sergey's Zeta 2 - http://www.malinov.com/Home/sergeys-projects/zeta-sbc-v2 - I built one of these plus the ParPortProp display board, it's really nice, CP/M with SD storage and a floppy controller in a nice compact package.
-The ECB-bus system, with a google group at https://groups.google.com/forum/#!forum/n8vem

(Some members of the group are in the process of moving a lot of the documentation about ECB boards to a new web host, but there is still active development going on of a new 68030 CPU board - the project is not dead).
 

JNZ

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That Zeta 2 SBC is adorable. I've applied to the S-100 group. I think I met the guy who runs it when he did an impromptu talk on the S-100 bus at VCF East this past April.
 

jgalinat

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Actually the guy that gave the impromptu talk was Herb Johnson, owner of the retrotechnology.com website and formally known as Dr. S-100. He did invite John Monahan up front to talk about some of his S-100 projects since he was in attendance. John is the man behind the s100computers.com website & projects.
Regards,
Jeff
 

new_castle_j

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Doesn't look like you can accept PM's yet, so send me an email, just add @yahoo.com to my username. I may be able to help get you started down the S-100 path.
 

JNZ

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Actually the guy that gave the impromptu talk was Herb Johnson, owner of the retrotechnology.com website and formally known as Dr. S-100. He did invite John Monahan up front to talk about some of his S-100 projects since he was in attendance. John is the man behind the s100computers.com website & projects.
Regards,
Jeff

Ah that's right! Thanks
 

JNZ

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Doesn't look like you can accept PM's yet, so send me an email, just add @yahoo.com to my username. I may be able to help get you started down the S-100 path.


Sent. You might have to check your SPAM folder, as it's from my own domain
 

JNZ

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It's a super nice board, runs the Z80 at 20 mhz.

Does anyone make a front panel compatible with the Zeta? I'm a sucker for a cool looking enclosure with as many blinking lights and computer-ey sounds as possible. Otherwise I feel like I'm just using an emulator.

(Incidentally, I love that Mike put a fan in the Altair Clone, but I wish there was a diskette sound board already.)
 

JNZ

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If hobbyists would accept new S-100 products with surface mount chips (even big SOICs), the S-100 could still be feasible. Not all those vintage S-100 boards were kits after all, and in their day, they were designed to be the best capability for the dollar, not a quaint relic.

Through-hole components are too much of an obstacle course today for new S-100 board products. It just adds to component cost, assembly labor while reducing reliability if the chips were bought from nefarious electronic recyclers.

I'd buy an SMD S-100 system. I'm not proud. As long as it's not just some ARM core processor running realtime Linux at 2 GHz, but actual logic gates and such.
 

Chuck(G)

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Well, if you're going SMT, a moderate-size FPGA could probably contain the CPU and just about any device that you'd care for.

...and it'd still be a Z80.
 

JNZ

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Well, if you're going SMT, a moderate-size FPGA could probably contain the CPU and just about any device that you'd care for.

...and it'd still be a Z80.

This is true. It's always awkward when one has to intentionally limit the technology you can use so as to attempt to recreate the magic and spirit of the original. For some I suppose that means sticking to PDIP, no matter how impractical.

Ah, if only we had time machines.
 
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