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SD card reader for Kaypro?

Hi! Well, in this case it would be fairly simple since there would be CBIOS source code examples available on the N8VEM wiki. There is already a CP/M with CBIOS source listing for the PropIO posted. If the shim socket approach works then there is no reason I can think of that it would not work for the DiskIO (FDC & IDE) board either. There is published CBIOS source code for that as well.

Why this idea of the shim socket to ECB didn't occur to me earlier is a mystery but it may allow all sorts of Z80 based computers to use N8VEM peripherals. However, as you said, they would require software to be written for them. Some peripherals support changing the IO address and some don't. PropIO allows for changing the IO address but DiskIO is fixed.

Thanks and have a nice day!

Andrew Lynch
 
Hi! A quick update on this sideline project. I have been busy working on the S100Computers.com and N8VEM S-100 boards and also the N8VEM SCG sound and color graphics board. However I did get a chance to design a simple PropIO shim socket schematic and PCB layout. It is very simple so it did not take long to do.

One of the N8VEM builders has a prototype PropIO shim socket and installed it on his KayPro. The good news is the KayPro boots and operates as it did before. The preliminary testing is positive since the builder is able to access the PropIO status port using the KayPro. He is in the process of writing a small test program to echo keyboard input on the VGA display. If the test is successful and we can establish reliable KayPro to/from PropIO communication. Then it is just a matter of writing the software so the KayPro can access the PS/2 keyboard, VGA, and microSD on the PropIO.

The test may not seem like much but if it works it establishes proof of concept of using a PropIO directly interfaced to a Z80 CPU. With some research and testing I think this could be extended to nearly any Z80 (socketed DIP 40) computer. That certainly is an interesting prospect!

Further, with some relatively simple glue logic I think this might even be extendable to 65xx/68xx style CPUs. The requirement being 5V operation and socketed DIP 40 chips. The glue logic would have to decode the upper 11 address bits to a simulated /IORQ signal. That would be I think a 74LS682 with a 8 position DIP switch, a 74LS32 and maybe an inverter with some option jumpers. Also /R/W* would have to be converted to whatever the PropIO uses.

I find it is interesting to think about new applications for the PropIO especially since it may pave the iway for a more general application of the other N8VEM boards to help vintage computers with small and/or inactive hobbyist communities. Especially if it doesn't require custom hardware development for each instance of application and we can solve the problem in a more general approach.

Thanks and have a nice day!

Andrew Lynch
 
Hi! The builder helping me prototype the PropIO <-> KayPro shim socket adapter has updated the thread. He's posted photos that confirm the PropIO is working from within the KayPro so I believe we have "proof of concept". That's good news!

What's left is the host software to drive the board. Accessing the PS/2 keyboard and VGA display is trivial. There is a 5 line MBASIC program on the thread for demonstration. Once the microSD is supported in the CBIOS it should be fairly easy to access it as well but would require a CBIOS to integrate into CP/M as a drive. Its certainly "doable" just requires someone with the desire to make it happen.

I've already designed a PCB for the Z80 shim socket adapter so what's left is more testing on various Z80 platforms and software development. The host does not have to be a KayPro as it could be any Z80 (DIP 40 socket) based machine although we need more testing to determine the level of compatibility. With the shim socket it is completely bus independent so this could be applied to S-100, ECB, proprietary, or even integrated/nonexpandable Z80 computers.

With a bit of creative interfacing I believe this concept could be extended to other CPUs such as the 65xx/68xx series, 8088/6, 68K, etc machines. However each new CPU would require a certain amount of interface logic on the shim socket PCB to work. The signals the PropIO needs are typical Z80 signals such as A0-7, D0-7, /RD, /WR, /IORQ, and the expected power rails (VCC & GND). I have some notional circuits to interface to the 65xx/68xx CPUs but they need testing.

What the project needs to move forward is more hobbyists willing to build an N8VEM board and the shim socket prototype to verify it will work on their host machine. Depending on hobbyist interest I may get some manufactured shim socket PCBs. They should be relatively inexpensive since the Z80 shim socket PCB is fairly small (2"x1.5") and single sided. I don't have a price estimate or ETA though. Before launching a project though I recommend some research into whether the PropIO or other N8VEM board would be compatible with the host machine such as CPU line loading, available IO ports, etc.

Thanks and have a nice day!

Andrew Lynch
 
Fascinating. Thanks for the info, Andrew. :)

I'd build an N8VEM board if I knew how.... but I don't. I do know how to buy nicely manufactured, tested and working boards that easily install. ;)
 
Hi! Well, if it were nicely manufactured, tested, and working boards they would be commercial items and cost big $$$. :) As home brew hobbyist items I can keep the costs low by just offering the PCB (or you can make your own since all the design information is free and publicly posted) and letting the builders make their own units. I am not as ambitious as Hargle is on the XTIDE to offer pre-assembled/tested units or even kits. I suspect after the beating he is currently taking on XTIDE that neither will Hargle on future projects...

Building your own units from the PCB is fairly easy due to the conservative design rules. The N8VEM PCBs are all DIP PTH construction with 0.1" feature size, wide traces with relatively large clearances. They are designed for beginners to reliably construct with minimal or no experience so it is about as easy as home brew electronics can be.

Of the many (hundreds?) of PCBs I've sent out I am not aware of a single unit that a builder could not get working to at least some degree -- after at most a correction or two. Normally boards work on the first try although some times they come with minor modifications. I have a standing offer for if that ever does happen to send me the board (after a good faith effort to do it themselves first) and I'll fix it on my bench. No one has accepted that offer yet to my surprise.

Your initial post has been sort of a catalyst for an idea that had been at the back of my mind for some time and now has a chance to finally express itself. Really it is about breaking the dependency of the N8VEM peripherals on the ECB backplane and the prototype has shown it can be interfaced directly to the CPU socket.

Maybe this idea will take off and maybe it won't. I hope it does but am realistic about its chances. Demand gets pretty thin as you traverse out to the edges of common vintage computers. I'll gauge the level of hobbyist interest before ordering any shim socket PCBs.

Thanks and have a nice day!

Andrew Lynch
 
I've already designed a PCB for the Z80 shim socket adapter so what's left is more testing on various Z80 platforms and software development. The host does not have to be a KayPro as it could be any Z80 (DIP 40 socket) based machine although we need more testing to determine the level of compatibility. With the shim socket it is completely bus independent so this could be applied to S-100, ECB, proprietary, or even integrated/nonexpandable Z80 computers.

...

Thanks and have a nice day!

Andrew Lynch

Soo... If one were motivated enough, one could adapt this thing into, say, a Mattel Aquarius and make it not-suck? :D
I suppose if one were to do that, they should put some extra RAM on the shim or somewhere since 4KB is about useless...

Sorry, I don't know why the Aquarius jumped to mind when you said any Z80 system ;)

__
Trevor
 
Hi! Well, yes, in theory at least. Does the Aquarius use a DIP 40 socket Z80? If so it certainly is a candidate. The only way to find out is to review the schematic and take a look. There is no substitute for doing the homework!

I imagine there could be designs that are incompatible and probably are somewhere if one were to look hard enough. However, most Z80 computers tend to follow similar patterns of implementation. Some things I would look for to indicate incompatible designs are if the /WAIT line pulled high with VCC. If so that would be a problem since most Z80 computers use pull up resistors to pull signals high. Does Z80 design allow the use of IO ports? I suppose someone could build a Z80 machine that only uses memory mapped IO although it would be quite unusual.

Ultimately it depends on the host computer design but if the shim socket fits it should work. The PropIO will appear as port IO on whatever address the builder selects. Line loading may also be an issue however since the PropIO uses buffered inputs and data bus transceiver it has minimal bus loading assuming the ribbon cable is kept short. Also, is the VCC capable of the additional load? Is the ground solid enough for the additional devices? So forth and so on. In the end though ultimately the only way to know for sure is to give it a try.

As for the RAM, that is a different story since the PropIO does not contain RAM on the memory bus. The N8VEM peripherals are accessed via IO ports not by shared memory. If a builder wanted to make a custom shim socket that also included a RAM expansion that would be possible I suppose but that is beyond the scope of this device. Certainly building a customized version of the PropIO for the Aquarius is not practical.

To be clear, I am not saying this device is guarranteed to work in all Z80 computers. I am saying it *could* work in a DIP 40 socket Z80 computer assuming the design is *compatible*. However, since the ECB is basically a buffered form of the Z80 bus to start with and the PropIO is similar to a common Z80 IO peripheral implementation the chances of it working in the arbitrary Z80 computer are fairly good.

What we do know is my claim that it *could* work is not an empty assertion. In at least one case, we took the PropIO built a shim socket prototype per design plugged it into a essentially random Z80 computer and it *did work* as predicted. I am confident there are cases out there where it won't work as well but until the research and experiments are done no one will ever know for certain.

I believe this approach could provide opportunity to a lot of "stranded" vintage/classic Z80 computers lacking key peripherals such as floppy drives, IDE, microSD, etc. I don't claim it to be the "magic bullet" to fix all Z80 systems since that would be nearly impossible. I've seen several cases of old Z80 computers where I've thought it would be nice to have an IDE interface for example or microSD instead of a broken floppy drive (or worse a cassette drive). For example fixing a KayPro with a broken keyboard or video display? Similar issues pop up here on vintage-computer.com forum regularly.

I hope this helps. Thanks and have a nice day!

Andrew Lynch
 
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This is an awesome project. :) I've got a Kaypro 10 and a 2 coming soon and I'd really like to be able to retire the MFM drive in the 10 before it dies. I never met a soldering iron I couldn't use, either. :)

Has any further progress been made? I'm really only interested in the SD portion of the project, but the other bits might come in handy with my Ampro Littleboard...

g.
 
Hi! Yes, we did some testing with the N8VEM on a KayPro and it seemed to work fine with the DIP adapter socket. Also tested it in a SpectraVideo and it worked there as well. No further testing though as PropIO has been sort of on a hiatus. Development continues but sort of quietly. I still haven't seen the final uSD software yet but at last word the builder writting it had it working and was finishing up the CBIOS for the N8VEM SBC. Certainly PropIO could be used in the manner with a KayPro as proposed and there is some experimental evidence to support it. However this is a "do it yourself" kind of project and probably would require a CBIOS to be useful.

Thanks and have a nice day!

Andrew Lynch
 
Thanks for the update Andrew. I'm pretty sure it would be "easy" to convert the N8VEM CBIOS over to the Kaypro.

g.
 
Hi! A build just posted some prototype code with a CP/M CBIOS to use the PropIO for the console IO (VGA and PS/2 keyboard) and storage (uSD).

http://groups.google.com/group/n8vem/browse_thread/thread/2ad5adc76d3c7770

With the prototyping on the Kaypro demonstrated earlier and this new PropIO code, I would claim there is now a SD card reader for the Kaypro. Likewise, using the same technique but with the DiskIO board there is also an IDE interface however that would still need to be demonstrated although based on previous testing I am fairly confident it would work.

Thanks and have a nice day!

Andrew Lynch
 
Hi! There has been a flurry of activity on the N8VEM mailing list recently due to the PropIO uSD CBIOS and ROM image announcement. The final software is not out yet but its amazing all that's happened with it so far. There are CBIOS and bootable ROM images for the N8VEM SBC. I think once the PropIO finally takes off it will be popular since it provides silent uSD storage and VGA and PS/2 keyboard interface.

This could also be a "shortcut" to a Kaypro (or any socketed Z80 AFAIK) uSD reader/writer and/or IDE interface this looks like a good opportunity. However, what's needed is someone familiar enough with the Kaypro to make a ROM that supports booting from the PropIO uSD and/or DiskIO IDE interfaces. I think the N8VEM SBC PropIO DiskIO code could fairly easily be adapted were someone inclined to do so -- not me as I am swamped. This could supplement a Kaypro with PropIO uSD and DiskIO IDE primarily. The PropIO also provides VGA and PS/2 keyboard and DiskIO also included FDC. I don't know how useful those would be but might help repair a system.

The PropIO has been demonstrated to work with the Kaypro with a shim socket so this is not too far fetched. It just requires the final piece -- the replacement ROM for the Kaypro motherboard. It can be any Kaypro model with a socketed Z80 CPU. I vaguely recall "SharkOnWheels" discussing such a project a long time ago but I haven't see him around for a while. If the project takes off I will make the "shim socket" PCBs to help easily plug the Eurocard boards into the Kaypro CPU socket. This is home brew Do It Yourself project so community involvement is critical for it to make it happen.

Thanks and have a nice day!

Andrew Lynch
 
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