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

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.

No front panel for the Zeta, but there is a Bus Monitor board for the ECB-bus N8VEM cards with blinking lights, and one for the S-100 boards - http://www.s100computers.com/My System Pages/SMB Board/S100 Bus SMB.htm

Switches are a little bit harder - the panels on the Altair and the IMSAI used some tricks to "jam" the contents of the switches onto the 8080 bus - which is why later-generation S-100 systems usually didn't have switches once EPROM boards were common for bootstrapping and terminals of some kind were available to use.

One of the users on the S-100 forum has created a 3/4 scale IMSAI panel reproduction, but it only works with a handful of CPU boards and not with the more advanced stuff like the x86 boards that John M. has been working on lately - http://www.s100computers.com/My System Pages/Mini FP Board/Mini FP Board.htm.

Once you start talking about things like FPGAs and things that aren't real S-100 hardware...well Mike's Altair Clone uses a microcontroller not an FPGA, but he has spent a ton of time making it pretty much cycle-accurate to the 8080 and there are like 39 videos showing how to use it on YouTube (hours and hours and hours of video). So if I wanted blinky lights but not real hardware that would probably be what I would get.
 
I am actually a bit surprised that the enhanced Z80 chips aren't more popular. They were certainly vintage: e.g. 64180, Z180, Z280, Z380...ez80. I wouldn't call the Rabbit R-series Z80-compatible as some Z80 instructions have been omitted or redefined.
 
No front panel for the Zeta, but there is a Bus Monitor board for the ECB-bus N8VEM cards with blinking lights, and one for the S-100 boards - http://www.s100computers.com/My System Pages/SMB Board/S100 Bus SMB.htm

Switches are a little bit harder - the panels on the Altair and the IMSAI used some tricks to "jam" the contents of the switches onto the 8080 bus - which is why later-generation S-100 systems usually didn't have switches once EPROM boards were common for bootstrapping and terminals of some kind were available to use.

One of the users on the S-100 forum has created a 3/4 scale IMSAI panel reproduction, but it only works with a handful of CPU boards and not with the more advanced stuff like the x86 boards that John M. has been working on lately - http://www.s100computers.com/My System Pages/Mini FP Board/Mini FP Board.htm.

That bus monitor card sounds awesome. I've requested access to the N8VEM site. I'd like to see documentation and schematics to see exactly what it does.

So the idea is to connect the Zeta 2 to an ECB backplane, put them in some kind of card cage (I heard a 19" card cage mentioned--are there examples out there of what people use?) and then add some of these N8VEM homebrew cards? It sounds like I'll also want a PPIDE board that lets me use an IDE hard disk, though I like the idea of starting with either 5 1/4" or 3 1/2" floppy disks.

It also sounds like the only major concession when you use the Zeta is a single RAM chip instead of a board of them. What is it about the Z80 that makes it so much easier than the 8080 to create an old system with original style PDIPs and modern PCBs?
 
That bus monitor card sounds awesome. I've requested access to the N8VEM site. I'd like to see documentation and schematics to see exactly what it does.

So the idea is to connect the Zeta 2 to an ECB backplane, put them in some kind of card cage (I heard a 19" card cage mentioned--are there examples out there of what people use?) and then add some of these N8VEM homebrew cards? It sounds like I'll also want a PPIDE board that lets me use an IDE hard disk, though I like the idea of starting with either 5 1/4" or 3 1/2" floppy disks.

It also sounds like the only major concession when you use the Zeta is a single RAM chip instead of a board of them. What is it about the Z80 that makes it so much easier than the 8080 to create an old system with original style PDIPs and modern PCBs?

The Zeta 2 is stand-alone only, there are several ECB single board computers, The N8VEM V2 using a classic Z80, the Mark IV using one of the "enhanced" Z80 chips, and an 80188 SBC.

You'd want something like the Mark IV (which has its own built in SD card slot for storage), and the PropIO V2 board for VGA+Keyboard. The ECB boards tend to integrate more features on a single board, while the new-build S-100 boards are more single-purpose-per-board.

One advantage of the ECB system is all the board run on 5V, so you can use a laptop-brick style 5V power supply to run the entire system - the S-100 boards still need the traditional +5/+16V dual supplies.
 
It also sounds like the only major concession when you use the Zeta is a single RAM chip instead of a board of them. What is it about the Z80 that makes it so much easier than the 8080 to create an old system with original style PDIPs and modern PCBs?

If you're talking about a real 8080A, several things. The 8080A is an nMOS implementation with a 3-rail supply (+5, -5, and +12) and pretty much requires the 8224 clock generator and the (bipolar) 8228 bus controller. The address lines on the 8080A are TTL-compatible, but can sink less than 2ma, so buffers were always used. The chip count goes way up.

On the other hand, the 8080A, being nMOS was lots easier to employ than its predecessor, the 8008, which is a pMOS design.

Remember that the Z80A came more than 2 years after the 8080A, at almost exactly the same time as the 8085, a much improved 8080A version. Two-chip system implementations were possible with the 8085. To cram the extra functionality (bit-bang serial I/O, extra interrupts, etc.) the 8085 did have to multiplex the data and address buses, which required a extra 8-bit latch to un-mux for systems not using internal de-muxing.

True, the Z80 did feature a 7-bit refresh counter for DRAM, but I don't think it was as important as some people seem to think. The 8085 was pointed squarely at the microcontroller market, where lots of RAM wasn't important.
 
If you're talking about a real 8080A, several things. The 8080A is an nMOS implementation with a 3-rail supply (+5, -5, and +12) and pretty much requires the 8224 clock generator and the (bipolar) 8228 bus controller. The address lines on the 8080A are TTL-compatible, but can sink less than 2ma, so buffers were always used. The chip count goes way up.

On the other hand, the 8080A, being nMOS was lots easier to employ than its predecessor, the 8008, which is a pMOS design.

Remember that the Z80A came more than 2 years after the 8080A, at almost exactly the same time as the 8085, a much improved 8080A version. Two-chip system implementations were possible with the 8085. To cram the extra functionality (bit-bang serial I/O, extra interrupts, etc.) the 8085 did have to multiplex the data and address buses, which required a extra 8-bit latch to un-mux for systems not using internal de-muxing.

True, the Z80 did feature a 7-bit refresh counter for DRAM, but I don't think it was as important as some people seem to think. The 8085 was pointed squarely at the microcontroller market, where lots of RAM wasn't important.

CrustyOMO did a single-board 8080A board - http://www.s100computers.com/My System Pages/8080 CPU Board/8080 CPU Board.htm - but all the first batch boards are sold and it will be a few months before he has more. It even has a built-in SD card slot for storage, 2 serial UARTS, and a parallel interfacre.

Combine that with the FPMini front panel board, and you'd have a pretty good 2-board IMSAI clone.

I am actually surprised how much new homebrew hardware there is out there!
 
Hello Chuck.

If you're talking about a real 8080A, several things.


Sorry for the odd-topic intrusion. Could you please contact me at: Support at ReActiveMicro dot com. I had an unrelated question and I can't seem to find a way to message you directly. Thanks!


Henry
 
CrustyOMO did a single-board 8080A board - http://www.s100computers.com/My System Pages/8080 CPU Board/8080 CPU Board.htm - but all the first batch boards are sold and it will be a few months before he has more. It even has a built-in SD card slot for storage, 2 serial UARTS, and a parallel interfacre.

What a bizarre design--using 8212s instead of LS373 or LS374s. After those came out, I don't recall any designs using the 8212--darned things ate about half a watt IIRC.

The NS 8250s, IIRC, didn't come along until 1977 or 1978; the chip of choice was the 8251 (ugly bugger!). Signetics 2651 USARTs were probably more popular in the day--they use a smaller package and have synchronous capability. Nobody remembers the 2650 MPU today, but the 2651 and 2661 were really good chips and outlived their associated MPU.
 
I do think that the S-100 IEEE-696 interface would be well placed on a FPGA to orchestrate; the bus is just a portal. If you treat the S-100 with more capable circuitry like the Multi-Bus systems of its day, an S-100 card cage would then be several complete SBCs that use the bus for accessing shared peripherals and processor-to-processor communications not unlike the way TurboDos sought to share processing load.

Special I/O boards are part of what made S-100 special and that would still be true, even with the processing residing on more or less SBCs on an S-100 card, they'd each be able to reserve and utilize that I/O.

And that ugly power system, is made nice today with low power components and various voltage conversion options. Even shutting down circuitry not in use makes the S-100 *toaster* a thing of the past.

The mistake that the IEEE-696 made, in my opinion, was not adding a higher density expansion bus, like Multi-Bus had. Today we could use that for high-speed serial channels or other possibilities.

If only... :)

John M's Floppy Disk Controller uses a captive Z80 of its own and custom firmware to abstract the commands needed to access multiple floppy formats into simple commands. And the Propeller Terminal board uses a Parallax Propeller chip (which has 8 microcontroller cores and onboard video generating circuitry) to drive a display with basically everything happening on 1 chip. When the new Parallax Propeller 2 comes out with more IO pins and faster speeds, I expect it will be possible to create a memory-mapped video board compatible with the IBM MDA using just address decode and the Propeller 2 chip.

I think going to the idea of a "motherboard" removed a lot of the flexibility to experiment and try new system configurations which S-100 allowed. When so much of the system is fixed to cloning an IBM PC or AT, a lot of innovation goes away.
 
I think the PCs and Macs were rushing to establish a professional computer for the everyman, and in doing so, wanted to make sure no one could ever attach any of their experimental designs. The OS made it difficult to write and integrate drivers, even though the circuitry was trivial and the card buses were easy.

I used PCs at work, but at home I found SBCs and S-100 more interesting. If I designed a AY3-8910 Programmable Sound Generator card for my S-100, writing code to make it work was easy. Never would even consider crossing the PC or Mac line in the sand with something like that. In my experience that is what killed a lot of the joy of early systems. PCs and Macs became only tools that you bought and bought cards for and bought software for and operated... everything was bound by the rules and regulations of the OS. So I never established any affection for those tools; if I like one better than a previous one, it was merely like preferring one saw or hammer better than another.

The PCs and Macs filled a need, certainly, and I exploited that tool-like utility. But it only offered joy in writing software applications under artificial IDEs. Never needed a soldering iron near them. And that's a shame. :)

I always complain that this modern generation of computing devices (smartphones, tablets) hides the underlying system to such an extent that no kid can even begin to tinker with the actual hardware, and the only thing they'll be able to do is what the operating system permits them to do. It's a walled garden. I recall feeling similarly when Windows stripped out actual MS-DOS mode. You guys, however, have the experience to take it one step further. I guess the ways things get locked down and consumerized has been a trend ever since the beginning of PCs.
 
I think the PCs and Macs were rushing to establish a professional computer for the everyman, and in doing so, wanted to make sure no one could ever attach any of their experimental designs. The OS made it difficult to write and integrate drivers, even though the circuitry was trivial and the card buses were easy.
...
The PCs and Macs filled a need, certainly, and I exploited that tool-like utility. But it only offered joy in writing software applications under artificial IDEs. Never needed a soldering iron near them. And that's a shame. :)

While I agree that S-100 is the most accessible and "fun" platform for prototyping, I think you're dismissing the many routes that you could (and still can) use to do custom HW/SW on PCs using their busses (ISA and EISA, and PCI specially).

Vector, and then Jade Computer and JDR - back in the day - and now MANY on and offshore suppliers offer ready-to-prototype ISA/PCI cards (with address decoding already included on the cards), that can make a project just as easy and fun as the old S-100 variants.

Also, MS (or PC) - DOS, was no harder to extend and write drivers for, than CP/M or say, N* DOS, way back when. I am not sure what you are referring to with "artificial IDEs", but MASM and older C compilers/linkers like D-SMET and Borland, or BASIC systems and their editors or "IDEs" were just as easy to use, and even more straightforward, than any of the primitive tools we had to use with S-100 / whatever-OS-you-had platforms. (IMO :'>)

Windows and other GUIs added A LOT of obfuscation to any type of prototyping I/O communication/drivers, but even then, the first versions were fairly simple, once the paradigm was learned...

gwk
 
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Just noticed this tread, for the S100 bus I would like to point out a few further things...
The nice thing about working with the S100 bus is that you can build up a multitude of different configurations (hardware & software) by plugging in different board combinations. RAM boards from a few K up to 16MB, (much more than that with 80386/80486 boards). Even now there is a wide range of CPU's, 8080, Z80, 6502, 68000/68010, 8088, 8086, 80286, 80386, hopefully soon a 80486 and later a Raspberry module... All kinds of I/O and video boards. In most case multiple CPU can reside in the same bus. This allows one to run "hog wild" with software. One often overlooked fact is the S100 bus allows one to have better control on hardware bud identification. Dead SBC motherboards are often quite difficult to debug and if they are more that two layers or without documentation usually impossible to fix.
 
Hi JNZ,

You might consider starting off with something like this:

http://www.ebay.com/itm/TEI-S-100-C...9e8fcb2&pid=100009&rk=1&rkt=1&sd=201422936728

This might be an inexpensive entry unit. Depending on what you find, and what you can or cannot get working, you could then continue on with some of the boards available at www.s100computers.com.

I was lucky to purchase a mostly working IMSAI some years ago ($1000), and I've since populated it with some additional vintage S-100 boards, and also purchased some of the boards available at s100computers (John Monahan).

BTW, John Monahan is an extremely helpful guy, as are many of the folks that you'll meet here on the VCF.

Good luck!

smp
 
I always complain that this modern generation of computing devices (smartphones, tablets) hides the underlying system to such an extent that no kid can even begin to tinker with the actual hardware, and the only thing they'll be able to do is what the operating system permits them to do. It's a walled garden. I recall feeling similarly when Windows stripped out actual MS-DOS mode. You guys, however, have the experience to take it one step further. I guess the ways things get locked down and consumerized has been a trend ever since the beginning of PCs.

That's not to say there are not a huge range of systems available were you can do hardware tinkering. At a very basic level there are PIC Chips, or for general purpose i/o there is the Velleman USB board..

http://www.rapidonline.com/design-technology/usb-experiment-interface-board-electronics-kit-70-4314/

which is basically PIC based. At the next level up there are Arduino Boards, MBED boards

https://www.mbed.org/

And if you need more power then there is the Raspberry PI or the Beagle Board Black.
 
Hi JNZ,

You might consider starting off with something like this:

http://www.ebay.com/itm/TEI-S-100-C...9e8fcb2&pid=100009&rk=1&rkt=1&sd=201422936728

This might be an inexpensive entry unit. Depending on what you find, and what you can or cannot get working, you could then continue on with some of the boards available at www.s100computers.com.

I was lucky to purchase a mostly working IMSAI some years ago ($1000), and I've since populated it with some additional vintage S-100 boards, and also purchased some of the boards available at s100computers (John Monahan).

BTW, John Monahan is an extremely helpful guy, as are many of the folks that you'll meet here on the VCF.

Good luck!

smp

That's an awesome looking system. The water damage is worrying, and might be worse than the seller estimates. Of course, all of these systems will need some type of repair or maintenance, it seems.
 
That's an awesome looking system. The water damage is worrying, and might be worse than the seller estimates. Of course, all of these systems will need some type of repair or maintenance, it seems.

Yes, I agree with your concern about the water damage description. I cannot make any of that out in the pictures shown. Those pictures show a very decent looking system. I suggest that you contact the Seller and ask if he might provide pictures of the boards individually.

If that's you bidding on the unit, I will not over-bid you. :)

smp
 
Yes, I agree with your concern about the water damage description. I cannot make any of that out in the pictures shown. Those pictures show a very decent looking system. I suggest that you contact the Seller and ask if he might provide pictures of the boards individually.

If that's you bidding on the unit, I will not over-bid you. :)

smp

That's not me bidding, so bid away. I may just monitor it and see what it goes for, as I need to get an idea for the current value of these things.
 
Hi All;

I agree with everyone else, that John Monahan and others are very friendly and Helpful..
I would slightly disagree in the use of newer surface mounted stuff against the old Pins, But I have plenty of the old Ic's and bare boards and wire-wrap sockets that I would go with the old pin type of Ic's, also I cannot see good enough to use surface mounting type of Ic's, so I would suggest that use what works for You..
Also, maybe Instead of getting a case and motherboard, You might get the Boards first and then You can decide on the case type and price range you may want.. And as a side note with John's boards you can get a motherboards and other boards and get them working without an enclosure.. Also, since John's boards are about $35 to $55 each for a blank boards, without parts and you could build them up as budget and parts are available.. You would/could have a working system before You decide on the enclosure you would want..

THANK YOU Marty
 
Hi All;

I agree with everyone else, that John Monahan and others are very friendly and Helpful..
I would slightly disagree in the use of newer surface mounted stuff against the old Pins, But I have plenty of the old Ic's and bare boards and wire-wrap sockets that I would go with the old pin type of Ic's, also I cannot see good enough to use surface mounting type of Ic's, so I would suggest that use what works for You..
Also, maybe Instead of getting a case and motherboard, You might get the Boards first and then You can decide on the case type and price range you may want.. And as a side note with John's boards you can get a motherboards and other boards and get them working without an enclosure.. Also, since John's boards are about $35 to $55 each for a blank boards, without parts and you could build them up as budget and parts are available.. You would/could have a working system before You decide on the enclosure you would want..

THANK YOU Marty

This is a neat idea too. In terms of chassis, I'm drawn to metal chassis and bus monitors or other useful and unique looking front panels. Is there a standard metal component that can hold S-100 bus cards? Something I can attach a backplane (or do you call them active-terminated motherboards?) to, so that at least I'm not connecting S-100 cards on my desk?

How do I verify the operation of something like a Z80 CPU card without also configuring a memory card and SIO board? An oscilloscope?
 
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