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NobodyIsHere
April 19th, 2007, 12:53 PM
Hi,

I found an interesting website with a technical manual for the System 80 with schematics for Z80 to S-100 bus interface.

http://www.webweavers.co.nz/system-80/manuals_technical.htm

This may be very useful information in building a bus bridge board from my Z80 ECBbus system to an S-100 bus.

Thanks!

Andrew Lynch

PS, my IDE HD project is nearly complete hardware and the CBIOS is feature complete and in debugging presently. It seems to work but last nights testing revealed a pretty major bug which was easily fixed. If anyone wants to build one of these IDE HD interfaces and use it in CP/M, let me know. I can post hardware design info, parts lists, sample code listings, CBIOS, etc. The CBIOS needs some optimizing though.

ahm
April 19th, 2007, 01:35 PM
If anyone wants to build one of these IDE HD interfaces and use it in CP/M, let me know.

I'm curious how your design compares to/improves upon Tillman Reh's GIDE (http://www.gaby.de/gide/) interface?

Thanks,
Andy

NobodyIsHere
April 20th, 2007, 03:41 AM
I'm curious how your design compares to/improves upon Tillman Reh's GIDE (http://www.gaby.de/gide/) interface?

Thanks,
Andy

Ahm,
I wrote a reply yesterday but apparently it never managed to post. Oh well.

In short, the difference between my circuit and GIDE is they use programmable GAL chips which can be hard to get and require special programming hardware ($100-$300) to make yourself. You buy them preprogrammed but that rather defeats the purpose of building from scratch. My circuit uses 8 standard and commonly available 74LSxxx chips and is easy to make and get the parts.

My circuit has all the design info available including parts list, schematics, test software, and a working CBIOS. That information is also available for GIDE but it is scattered about the internet.

I do not have any problem with GIDE as it is a fine interface but it uses GALs which are not homebuilder friendly in my opinion.

Thanks!

Andrew Lynch

NobodyIsHere
April 20th, 2007, 08:58 AM
More information on the S-100 expansion bus for the System 80. Apparently there were some S-100 expansion bus devices created for the platform. The most direct System 80 <-> S-100 interface is the X-4024 found here:

http://www.webweavers.co.nz/system-80/manuals_tm3_drawing%204.15_X-4024%20S-100%20interface%20schematic.jpg

This circuit is appealing but would require additional logic between it and the ECB to properly create the signals it is expecting to be present on the System 80 expansion connector. Those appear to be very similar to the TRS-80 Model I bus control logic.

Regarding the Z80 to S-100 bridge, the Exidy Sorcerer had an expansion chassis using very similar Z80 bus signals on their expansion connection. Full schematics for the computer and the S-100 chassis are available here:

http://www.trailingedge.com/exidy/

In addition, there is an excellent book I just bought which addresses the theory behind the S-100 bus and also other contemporary microcomputer buses such as TRS-80 I. Interestingly, this book has an appendix on the conversion of the TRS-80 I expansion bus to the S-100 bus including circuit diagrams. The TRS-80 I bus is Z80 based and similar in principle to the ECBbus which could be a very direct path for an ECB to S-100 bridge circuit.

http://www.amazon.com/gp/product/0672218100

Thanks!

Andrew Lynch

chuckcmagee
April 20th, 2007, 10:11 AM
I built a S-100 to TRS-80 bus converter in 1981. Tandy had a voice synthesizer that I wanted to use. I got the bus converter diagram out of a Popular Electronic mag. I got the thing talking fine so it does work.

NobodyIsHere
April 20th, 2007, 10:14 AM
I built a S-100 to TRS-80 bus converter in 1981. Tandy had a voice synthesizer that I wanted to use. I got the bus converter diagram out of a Popular Electronic mag. I got the thing talking fine so it does work.

Would you mind scanning that article and posting it here?

Thanks!

Andrew Lynch

chuckcmagee
April 20th, 2007, 10:34 AM
Well, I did this in 1981 -- the magazine is LONG gone, think I have moved 8 times since then.

NobodyIsHere
April 20th, 2007, 11:00 AM
Well, I did this in 1981 -- the magazine is LONG gone, think I have moved 8 times since then.

OK.

Maybe someone with the magazine will see this thread and post the article. I'll bet someone on these forums has that magazine sitting somewhere on a shelf.

Thanks!

Andrew Lynch

NobodyIsHere
April 21st, 2007, 07:55 AM
Hi!

Did some more research on this project and found a book based on a recommendation here called "The S-100 & Other Micro Buses" by Elmer Poe and James Goodwin. I believe this book holds the keys to unlocking the Z80 ECBbus to S-100 bridge project.

I have made a brief scan of some of the book to illustrate my point. I recognize the work is copyrighted so I claim this is "fair use" under the education exemption as this is engineering continuing education project. At any rate, the scan is quite brief and not the entire work so if anyone has any problem with it, I will remove it. Unfortunately, I cannot attach it to this message as it is too large (~1.8 MB).

The general outline of the project is in two major components:

First, is a Z80 ECBbus to TRS-80 Model I conversion board mounted on the ECBbus passive backplane. The ECBbus already contains most buffered Z80 bus signals for the address, data, and most of the control lines and they should provide sufficient information for this project. The basic schematic is a subset of the circuit on pages 44-51. The primary exceptions being /RAS (pin 1), /CAS (pin 3), and MUX (pin 16) will not be connected as they have no corresponding S-100 counterparts on the other side of the interface. This is actually a lucky break since /RAS, /CAS, and MUX are used for DRAM address decoding. They are timing sensitive and derived from the TRS-80 Model I 10.6445 MHz clock which is not present on the Test Prototype. Some signals will have to be added to my existing Test Prototype ECBbus subset such as phi, /M1, and /HALT. Fortunately, those signals are already part of the ECBbus standard so they should not cause an issue. The ECBbus bridge board would export its signal via 40 pin braided cable and IDC headers.

http://www.hardwarebook.info/ECBbus

Second, is an S-100 interface board with the circuit captured in the schematics on pages 167-170. It would be connected to the first board via a IDC header and the 40 pin braided cable. The S-100 card would be plug into a passive backplace S-100 motherboard and the bridge board would control the bus. I plan to make the S-100 card using a wirewrap prototype board. Eventually, it may get replaced with a custom PCB as S-100 cards are scarce and I would like to avoid permanently dedicating one.

So, that is the plan. Anyone have comments or questions?

Thanks!

Andrew Lynch

PS, I found an earlier version of the S100 book online at:

http://www.hartetechnologies.com/manuals/Unclassified/S-100_and_Other_Micro_Buses.PDF

The pages numbers are probably wrong but the content and relative locations are the same.

This project is in slow motion as I finish up the FDC for the Test Prototype and get my S-100 Chassis rebuilt. I ordered some S-100 prototype boards so it is still moving. The next step is to translate the diagrams into real schematics and layout a circuit.

vk4akp
February 10th, 2009, 05:59 PM
Hi guys, came across your thread and figured you might be able to help our group out.

We are currently looking for System 80 parts to try and put together a working display.

We have been very lucky in obtaining a X-4010, S-100 unit for the System 80.

Also on the way is a System 80 once the old owner has time to locate and retrieve it from storage.

If anyone would like to help out by looking at the following link http://shazam.zapto.org/phpBB/viewtopic.php?f=10&t=11&p=14#p14 and telling us what we actually have and where to go from here as far as suitable drive mech's, cables etc etc it would be great.

Also if you have any idea's as to further expansion and modern day revamps like Compact Flash storage mods etc.

tnx,
vk4akp - SJ of The RCC.

.-.-.

NobodyIsHere
February 12th, 2009, 04:00 AM
Hi! I am not really an expert with the System 80 although the X-4010 interface has definitely captured my attention. This project has been rather on the back burner for quite a while as other things get resolved. However, my plan is to create an ECB to S-100 bridge and do it in three parts.

First the N8VEM (http://n8vem-sbc.pbwiki.com/) SBC (http://n8vem-sbc.pbwiki.com/folder.php?folder=SBC+PCBs) and ECB backplane (http://n8vem-sbc.pbwiki.com/folder.php?folder=ECB+backplane+and+BITC)which are similar to the TRS-80/System 80 core SBC design.

Second, build an N8VEM S-100 bus (http://n8vem-sbc.pbwiki.com/f/Printing%20S100-Backplane-full-brd.pdf) for hobbyist prototyping. It will be small but useful as either a stand alone or connected to the N8VEM system. I tried to post this on the CCTALK mailing list for requesting comments on the design but those posts disappeared into the bit bucket. CCTALK is notorious for that.

Finally, reverse engineer the X-4010 bus interface logic and recapture it as an ECB board. The X-4010 interface is a pretty good S-100 bus as it supports most of the signals including the vectored interrupts. The bridge board would plug into the N8VEM ECB backplane and use *short* cables to connect to the S-100 bus. That I can build a prototype with ECB prototype boards and will get going on that once some of these other "in work" projects settle down (Hargle's ISA 8 bit IDE controller, N8VEM Disk IO, N8VEM Zilog Peripherals, N8VEM 6809 host processor, etc). Those projects actually have hardware in some fashion like PCBs and prototypes so have to take priority over the planned ECB to S-100 bridge board but eventually they'll will clear the bench.

That the plan at least. The first part (N8VEM SBC and ECB backplane) already exist and the S-100 bus is nearly ready to go to PCB manufacturing. I would appreciate any comments, questions, suggestions on the S-100 backplane and if anyone is interested in getting a PCB please let me know. I will do a small batch PCBs for testing and to measure if there is any, and if so how much, hobbyist interest.

Thanks and have a nice day!

Andrew Lynch

vk4akp
February 12th, 2009, 06:05 PM
Hi Andrew,

I'm really keen on all of this. I'm glad I came across your post!

I'd be interested in knowing more on the costs involved for the blank PCB's etc.

Also can you tell me is the reason there is only 3x connectors on the S100 bus? IS this a limitation of the S100? Or could one produce a backplane to accommodate more cards? It just seems to me that 3 cards is very limiting?

~Ken~
P.S. If you would like to P.M me a USA number I'd love to chat with you about this if you have the time.
.-.-.

NobodyIsHere
February 12th, 2009, 07:57 PM
Hi Andrew,

I'm really keen on all of this. I'm glad I came across your post!

I'd be interested in knowing more on the costs involved for the blank PCB's etc.

Also can you tell me is the reason there is only 3x connectors on the S100 bus? IS this a limitation of the S100? Or could one produce a backplane to accommodate more cards? It just seems to me that 3 cards is very limiting?

~Ken~
P.S. If you would like to P.M me a USA number I'd love to chat with you about this if you have the time.
.-.-.

Hi Ken! Thanks! Yes, I have been considering this project for some time now and as the components are being produced it is becoming more realistic.

The S-100 backplane will have 4 slots. I would like to keep it small so it is low cost for the builders. The purpose is two fold; it is a low cost stand alone S-100 bus vintage computer hobbyists can use to test, repair, and prototype with rather than using expensive, large, and hard to repair if damaged vintage S-100 chassis. The backplane has to be small enough to fit on a bench without a case and still have room for power supplies.

The second purposes is to use the 4 S-100 slots to as an extension of the N8VEM system. Since the N8VEM system already has a SBC, Disk IO board, ECB bus monitor, ECB prototyping board, etc, the S-100 bus would not require many cards. Probably only one or two to fill a role in a system.

Keeping the PCB area small is key to low cost. Also, keeping the bus length very short means it does not require termination either active or passive to keep the electrical performance reasonable. My goal for cost is to keep it consistent with the other N8VEM project boards at $20 each plus shipping. If I can keep the PCB area small enough it might be possible.

In theory we could do a larger S-100 bus but I would like to see the bridge board done first and it needs a small S-100 bus for that. The bridge board would work with either I suppose but lets see if the small one generates any interest.

Thanks and have a nice day!

Andrew Lynch

vk4akp
February 12th, 2009, 08:35 PM
Hi Andrew,

OK. Well that all sounds very good.

I'll have to study this all further and then get some PCB's from you.

Are all the IC's still readily available new? Things like the Z80 etc?

As for the S-100 board, I'd love to see a 12 slot one designed and etched.
There's nothing worse then building something to find out it doesn't have enough expansion potential.

The X-4010 I have now for example with the standard two cards only leaves one slot free.

If you offered a 12 slot version I could see System 80 / Video genie / PMC-80, TRS-80 people being interested as well.

Can the N8VEM computer emulate or run TRS-80 / System 80 or other old Z80 based retro software?

.-.-.

NobodyIsHere
February 13th, 2009, 03:39 AM
Hi Andrew,

OK. Well that all sounds very good.

I'll have to study this all further and then get some PCB's from you.



Hi Ken! Thanks! If you are interested in the N8VEM project, check in with the mailing list and the wiki. It is an open project with lots of activity and development ongoing.

http://groups.google.com/group/n8vem

http://n8vem-sbc.pbwiki.com/

All the PCBs are available and are $20 each plus shipping. All the parts are commonly available stuff except for the FDC9229BT on the Disk IO board which while a bit hard to get is still available commercially.

The ECB to S-100 bridge board is essentially a subproject within the N8VEM project. Building a bridge has been an idea I've been working on and thinking about for quite a while.





Are all the IC's still readily available new? Things like the Z80 etc?

As for the S-100 board, I'd love to see a 12 slot one designed and etched.
There's nothing worse then building something to find out it doesn't have enough expansion potential.




Possibly I may do a larger one later on but a small S-100 backplane can still do a lot of stuff. For example, you could put on a SBC with serial port, SRAM board, and FDC board and still have a slot left over. The primary purpose is for the ECB to S-100 bridge similar to the X-4010 and to support prototyping and peripheral development. As a side effect the small backplane would be useful for other things too as a bench backplane.





The X-4010 I have now for example with the standard two cards only leaves one slot free.

If you offered a 12 slot version I could see System 80 / Video genie / PMC-80, TRS-80 people being interested as well.

Can the N8VEM computer emulate or run TRS-80 / System 80 or other old Z80 based retro software?

.-.-.

Larger S-100 backplanes start to get into some tricky areas such as needing termination and generally require large PCB. A twelve slot S-100 backplane even at cost would be still around $60 minimum. It would be three times the size plus need side support, terminators, etc. It adds up fast!

The N8VEM SBC currently running CP/M 2.2 and a RAM monitor but could run other OSs. Although there is some similarity of aspects of the TRS-80 with the N8VEM SBC they are not compatible. The TRS-80 has a lot of IO the N8VEM SBC does not include. However, I would not rule out if a determined builder were to craft a peripheral that added TRS-80 compatibility. Its just not on my list of things to do.

After we get these IDE controllers fixed (Disk IO and XT-IDE) the next project is the 6809 host processor. I have an early prototype in a breadboard on bench right now. I am still awaiting some parts though to finish it. Then I'll make a new one using an ECB prototype board for more testing.

Thanks and have a nice day!

Andrew Lynch

Dr_Acula
February 15th, 2009, 04:09 PM
And just to reply to this question"Are all the IC's still readily available new? Things like the Z80 etc?"

Yes, all the parts are available and from multiple sources. Eg the Z80 from futurlec for $1.95 or the cmos lower power version for $2.90.

vk4akp
September 16th, 2009, 12:10 PM
Hi, Just re visiting this thread again as we have a bit of renewed interest.

Recently our group finally got a System 80.

I'm now wondering how things are going with the S-100 PCB's?

Also reading your comments again I can see that maybe a 12 card board would be a big ask in the early designing stages and cost wise etc.

However I do wonder if perhaps a slightly bigger one could be looked into maybe 6 ports?

I am thinking that for the System 80 the following would be nice.

1. Ram expansion card.
2. IO card (rs232, centronics, FD controller).
3. IDE controller.

Doesn't leave a lot of room for future expansion on a 4 slot board.

Also can any of your existing card designs be utilised in the S100 back plane with a System 80 or TRS80? Very keen on the idea of adding an IDE hard drive for example.??? :)

Once again thanks for all your fantastic work in this retro computing area.

BTW, Have put other System 80 enthusiasts on to this thread also so expect more interest soon! ;)

~Ken~
.-.-.

NobodyIsHere
September 17th, 2009, 05:05 AM
Hi, Just re visiting this thread again as we have a bit of renewed interest.

Recently our group finally got a System 80.

I'm now wondering how things are going with the S-100 PCB's?



Hi! Thanks! Well, I've made some progress. I had a batch of S-100 backplane and S-100 prototyping boards made. The good news is they appear to work fine. All the units are with their new owners so I am out of boards. The bad news is that they cost more than I would have preferred so they were slow to find new owners.

Right now I am gathering up interested committed buyers on a waiting list. If we get the quantity high enough I'll do another order but am not willing to it all on spec for fear of getting an expensive box of PCBs no one wants. I am thinking 10 for the backplane and 20 for the prototyping board brings some price improvements. With those quantities the PCBs are probably on the order of $20 each. Larger quantities would be better though and get the price down.

As of yesterday PM, I had 3 backplane and 6 prototyping boards reserved and noticed this morning a couple more of each so the totals are slowly ticking upward. With every addition to the waiting list the planned new purchase becomes more plausible.




Also reading your comments again I can see that maybe a 12 card board would be a big ask in the early designing stages and cost wise etc.

However I do wonder if perhaps a slightly bigger one could be looked into maybe 6 ports?



The S-100 backplane PCB is 6 slot.





I am thinking that for the System 80 the following would be nice.

1. Ram expansion card.
2. IO card (rs232, centronics, FD controller).
3. IDE controller.

Doesn't leave a lot of room for future expansion on a 4 slot board.

Also can any of your existing card designs be utilised in the S100 back plane with a System 80 or TRS80? Very keen on the idea of adding an IDE hard drive for example.??? :)

Once again thanks for all your fantastic work in this retro computing area.

BTW, Have put other System 80 enthusiasts on to this thread also so expect more interest soon! ;)

~Ken~
.-.-.

I have looked at the X4010 and X4020 as a possible ECB to S-100 bridge board but that project is on the back burner for now. There is a lot of activity on the Eurocard ECB side and I'd like to do some S-100 projects maybe this winter.

A System 80 bus to ECB bridge might be pretty straight forward though. Basically a Z80 CPU shim socket to PCB with bus control logic, buffers and transceivers. Then you could use N8VEM peripherals directly.

I haven't looked into it but it may be possible to extract the signals for ECB out of the System 80 system bus connector too. If all the Z80 bus signals are present or could be easily derived then it would be fairly straight forward to do.

Thanks and have a nice day!

Andrew Lynch

vk4akp
September 17th, 2009, 05:35 AM
Hi Andrew, Yea we'll take a board. I do need to understand better though whats needed to get a working S100 bus on a System 80 and or TRS-80.

When you get closer to knowing let me know what we would need and prices etc.

Also adapting your projects to use the IDE cards etc on a System 80 would be fantastic! :)

~Ken~
.-.-.