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Tor
June 5th, 2011, 01:12 PM
I'm looking for a setup which would allow me to experiment with CP/M again (I used to program and hack on CP/M systems in the 80's). Been through some emulators, but it's not entirely satisfactory. So now I'm looking for some real hardware to fool around with.

I'm more into the programming aspect than the hardware building part, although I can do some of the latter I figure N8VEM is too much hardware for me - particularly as collecting all the parts from this side of the pond would be costly and a lot of effort.

The eZ80sbc (eZ80sbc.com) seems like it would fit what I want - but as usual it looks like I got aware of it a few years too late from what I can tell - there doesn't seem to be anything for sale there anymore.

So, following the eZ80 idea, I'm currently looking at what Digikey has to offer, and here's where the current problem is - it's hard to tell exactly what you get with their Zilog kits. After some searching I came up with this page: http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=2621773&k=ez80%20development
The three top entries appear to be what I should look at. The first one (269-4671-ND) is, from what I can tell, a little board with an ethernet port and more. There's a PDF link to the right which says:
o 50MHz
o 10/100 Base-T Ethernet
o 512KB SRAM
o 256 KB Flash mem
o 1MB off-chip NOR Flash mem
o RTC clock with battery
and more
Way more than enough to run CP/M I think. This kit includes just this board afaict.

Then there's the next one down, (269-4561-ND), which, from the picture, _seems_ to include the first eZ80 board, and the specs (from another pdf) may agree. And there's a board to piggyback it on. This set includes a lot of other stuff, including power supply and compiler and things which should make things easier to start with.

The third one on that page (269-4560-ND) is much cheaper than the one above, but seems otherwise to be similar. First I thought that the module (called 'EZ80F91 mini module' in the description) was different from what comes with the 4560-ND, but now I'm not certain. The larger card seems to be different. But both the 4560 and 4561 points to the exact same PDF document, the 'EZ80F91 Dev Kit Users Manual'.

So, assuming that this would be a possible way to my own eZ80-based SBC capable of running CP/M and other interesting stuff, what am I gaining or losing by the different DigiKey selections? Are any of you familiar with their (somewhat terse) product descriptions?

-Tor

tingo
June 7th, 2011, 01:48 PM
Does your CPM machine have to be entirely a hardware machine?
They have propeller based boards that emulates a z80, and that runs CP/M now. Example:
http://www.cluso.bluemagic.biz/
http://forums.parallax.com/showthread.php?116893-RamBlade-Prop-SRAM-microSD-addon-to-run-ZiCog-CPM-PropDos-Catalina-etc

Tor
June 7th, 2011, 02:46 PM
Interesting. I haven't come across that one before in my searches. I'll add it to the list of things to look closer at.
Thanks!

-Tor

Chuck(G)
June 7th, 2011, 03:33 PM
I don't know. The ez80 made a big splash initially, but I hear mostly crickets chirping out there now. Zilog has been on life support for several years and has spun off a number of divisions, but now it's part of IXYS--and I don't know if that's good or bad.

Howard Harte did an eZ80 prototype CP/M system (http://www.ez80sbc.com/), but I don't know if it ever went anywhere.

So, before you part with your filthy lucre for an eZ80 dev kit, I'd look hard.

Tor
June 8th, 2011, 01:13 AM
Yes, Howard Harte's system looks like what I was after (I briefly mentioned it in the posting), but it doesn't seem to be active. But I know there was at least one guy who bought one and liked it, a few years back.

NobodyIsHere
June 8th, 2011, 03:47 AM
Hi,

I suppose you could try to get a P112 from David Griffin or SB-180 on eBay. As I recall there was a recent batch of P112's available as kits using existing PCBs. I don't know if any are still available though. There was an effort to replicate the P112 several years ago on comp.os.cpm but sadly nothing came of it.

http://groups.google.com/group/comp.os.cpm/browse_thread/thread/9ed2a608348404a1/0b17bf5a75d34db5

It is the lack of options on Z80 based kits or even PCBs which lead to the creation of the N8VEM SBC in the first place. It is a very frustrating situation. I recall trying to find the Zilog Z180 evaluation boards in vain but they aren't available either.

Digikey says they have the ez80 modules available ~$75 for but the prices they are charging you could more easily build your own. The downside of the ez80 modules is you are still stuck with a closed proprietary design that's not expandable or easily modified. When searching on Digikey remember to select those items they actually have in stock. They carry many Zilog items as "non-stock" meaning they would have to special order them if they are still available. In other words, their online catalog is full of zombie products that show up in searches but aren't actually available.

There was a more recent (2010) attempt at a P112 cloning but that fizzled as well. You might be well off to just get a perf board and wire wrap your own Z80 SBC design. You certainly could do that for less than $50 if the design were kept simple enough. That's how my Test Prototype Z80 board (the N8VEM SBC predecessor) came into existence.

Good luck and please post updates on what you find. Thanks and have a nice day!

Andrew Lynch

carlsson
June 8th, 2011, 05:31 AM
Out of curiosity, does nobody have a spare N8VEM ready built to sell Tor for self costs plus a little for assembly and testing? In that way he can join the N8VEM community on the software side without having to scout for parts and assemble the board(s) himself? I never quite got around to have my five N8VEM's working. Three of them remain unbuilt with a pile of hopefully compatible components covering the whole board. If I had managed to get it working, I would without hesitation have offered Tor one of those.

Tor
June 8th, 2011, 05:54 AM
It's an unfortunate truth that if it has to be collected&assembled&built by me then it won't be finished.. that's what history tells me. I even have an unfinished Nascom 2 from the end of the seventies stowed away somewhere. So, even though I have a background in electronics (and I've designed and built stuff at work back in the eighties), and I'm a qualified TV repair guy (not very useful these days) and electronics engineer, I realised early on that if I want to build something it must be software, not hardware. So I've been using programming ever since to satisfy my urge to create.

That hasn't stopped me from checking out the N8VEM and S100 project pages with fascination ever since I heard about that (quite a while ago). Looks lovely. And those propeller setups that tingo linked to - great stuff. Alas, that also has to be built from scratch, so, knowing myself, that won't happen. I'm not even able to build a proper box or cabinet for those boards that I do own. It's not what I'm any good at. I stop at connecting modules. I can solder and all that, of course, but I limit that to repairs, not building.

Anyway, that's why I look at things like those plug-in-and-go (as far as hardware is concerned) eZ80 dev. kits, and that very nice eZ80sbc.com kit (I'm just a few years too late for that last one.. :-))

-Tor
(and just for the record - 73, de la1rha)

p.s.
Anders, knowing that you would sell me one if you had a spare one available is much appreciated. Cheers.

aitopes
June 8th, 2011, 06:30 AM
Hello!

I am trying to find one simple "Z80 SBC" board, too.

The poject z80test (http://www.z80.info/gfx/z80test.gif) looks good for me. But ┐Exist some ROM file for this project? :confused:

Thanks!

PD: lynchaj, I am very impressed by your work. Congratulations!

NobodyIsHere
June 8th, 2011, 06:38 AM
Out of curiosity, does nobody have a spare N8VEM ready built to sell Tor for self costs plus a little for assembly and testing? In that way he can join the N8VEM community on the software side without having to scout for parts and assemble the board(s) himself? I never quite got around to have my five N8VEM's working. Three of them remain unbuilt with a pile of hopefully compatible components covering the whole board. If I had managed to get it working, I would without hesitation have offered Tor one of those.

Hi,

There has been only one sale of a completed N8VEM SBC as far as I know. Very rarely P112 and/or SB-180 SBCs come up for sale on eBay and similar auction sites.

http://groups.google.com/group/comp.os.cpm/browse_thread/thread/c64c68ef55b78472#

I think once builders get their SBCs working (regardless of what kind it is) they tend to hold on to them forever.

What would be neat would be a pre-assembled N8 (not the SBC but the all in one Z180 home computer) board or at least one with all the passives and sockets soldered. I imagine that each board would cost a fortune though considering how many components are stuffed into a 6" x 10" PCB.

The cost of a pre-assembled board compared to a bare PCB increases the cost by roughly an order of magnitude as best I can tell. For small quantities it is cost prohibitive.

Thanks and have a nice day!

Andrew Lynch

PS, it just occurred to me you could also ask on the N8VEM mailing list. I suppose it is possible there would be builders there who would sell completed boards if they've moved on or have duplicates.

NobodyIsHere
June 8th, 2011, 06:50 AM
The poject z80test (http://www.z80.info/gfx/z80test.gif) looks good for me. But ┐Exist some ROM file for this project?


Hi,

As I recall there is a sample ROM image posted on the same website in the general area. The board is very simple and the code is as well.

http://www.z80.info/z80sourc.txt

That design was the original inspiration for what became the N8VEM SBC with a lot of influence from the PROF80.

Thanks and have a nice day!

Andrew Lynch

Chuck(G)
June 8th, 2011, 08:45 AM
I don't think I've ever seen it mentioned here, but ETT, the Thai manufacturer of little modules (e.g. USB, ethernet) for hobbyist prototyping also has a line of training boards, amongst which are several Z80 models. Not enough perhaps to get CP/M going, but probably fun to fool with.

I suspect that if they can't be ordered directly, one might get them through Futurlec.

ETT Catalog (http://www.etteam.com/pdf2011/en/Catalog_2011_English.pdf)

NobodyIsHere
June 8th, 2011, 08:46 AM
Howard Harte did an eZ80 prototype CP/M system (http://www.ez80sbc.com/), but I don't know if it ever went anywhere.

So, before you part with your filthy lucre for an eZ80 dev kit, I'd look hard.

Hi,

An important note about Howard's SBC is that it uses the eZ80F91 as a component in his own board which provides much of the interface IO. In other words, the eZ80F91 module from Digikey is not equivalent to Howard's nifty CP/M computer. To use an eZ80F91 from Digikey you'd have to basically design an IO board to power, mount, and supply IO devices to run CP/M. I suspect designing an IO board to mount an eZ80F91 is roughly equivalent to designing a simple Z80 SBC from scratch and probably more expensive.

Chuck, I am sure you know this already but it is a subtle point which may not be apparent to everyone reading this thread.

Thanks and have a nice day!

Andrew Lynch

Chuck(G)
June 8th, 2011, 09:21 AM
Andrew, my mention was mostly meant to point out that someone had done a kit using the eZ80 ÁC that ran CP/M. It's not clear to me if the devkit from Digi-Key has ever been used to do that.

There are certainly lots of emulators, as well as FPGA designs that do run CP/M, however.

If the OP is shy of building, then perhaps an FPGA kit might be the best way to experience several vintage CPU cores without lifting a soldering iron. There are lots of designs out there, including sutff such as a PDP-11/73 implementation.

Tor
June 8th, 2011, 11:50 AM
Andrew, my mention was mostly meant to point out that someone had done a kit using the eZ80 ÁC that ran CP/M. It's not clear to me if the devkit from Digi-Key has ever been used to do that.
I've found only one which uses the devkit: http://projects.steamboat.de/html/ez80_2.html (bottom half of page). The next page refers to another ez80 attempt (which doesn't mention any devkit and is very short), that page doesn't exist anymore and the z80cpu.eu mirror is kind of offline at the moment, but another route to that mirror is http://www.e-tech.net/~pbetti/mirrors/www.vegeneering.com/eZ80_CPM/index.html
The only I/O is an MMC card.

-Tor

mnbvcxz
June 15th, 2011, 02:29 PM
You should have a look here
http://www.retroleum.co.uk/v6z80p/

He makes the v6z80p which runs at 16mhz and has 1152KB ram and is developing an eZ80 board, both are ready-built and reasonably priced, neither runs CP/M yet but you may be able to install it yourself.

Tor
June 16th, 2011, 01:34 AM
Thanks for that. I've contacted the v6z80p guy. It didn't show up in any of my google-fu attempts so I wouldn't have found it without your tip.

-Tor

mnbvcxz
June 16th, 2011, 05:59 PM
Glad I could help.

Tor
October 9th, 2011, 01:28 PM
As I started this thread I should also provide an update I think..

So, how did it end up?

- I took the idea from Tingo and purchased a Propeller-based kit (I mentioned earlier that I'm not so keen on building, but that's not because I have a problem with the actual soldering&building, it's because if I don't have all the parts I always end up with something not finished. The Dracblade kit I found included all the components and parts, so I was good to go). This board can run a Z80 emulator (and CP/M) written for the Propeller microcontroller. The board is also very versatile and can be used for lots of stuff. Before I got the kit I bought a QuickStart board (only $20 at the time, and $2.09 shipping to Norway) from Parallax, to check it out and test all the development tools on Linux. That worked great, so I then ordered the Dracblade PCB and components, from the designer in Australia.

- I also got a Z80 pre-built board from the link that mnbvxz provided, that turned out to be an excellent board and I'm very grateful - I would never have found it without your link. It runs a version of CP/M that another guy ported quite a while ago, but he didn't follow up with what changes he did etc. so I plan to do my own port - that's what I wanted to do anyway. This board is also very versatile and can run a cycle-exact Spectrum emulator, for example.

- And, finally, I got _another_ board (this time complete with case) from the same guy, a 50MHz eZ80 board. This is also a great board. It didn't take long for another guy to have an Apple I emulator running on it. I plan to hack on getting CP/M running on this one too, of course..

Now, if any of you could find me a link where I can purchase more hours per day, then I would be utterly grateful! :) 24 just won't cut it.

-Tor

Dr_Acula
October 11th, 2011, 09:16 PM
I should check these threads more often :)

Anyway, nice to hear that my board works and you have CP/M up and running. I should add that this group here have always been very helpful to me regarding CP/M questions.

Next thing you will probably find is that the emulation is too slow (and it is, because it is only about a 2Mhz emulation). We need to think about cunning software changes to increase the speed. For instance, the emulation of a 'push' opcode takes about 10 instructions in propeller code (at 80Mhz) and then goes off and does two single byte writes to external memory which take 20 instructions each. 50 instructions to do one Z80 opcode. Those writes are far too slow and I am sure we can do better with one less latch and a caching algorithm.