• Please review our updated Terms and Rules here

Interested in a home brew Z80 computer project?

Hi! I heard this weekend that one of the N8VEM builders got the PropIO VGA, PS/2 keyboard, and microSD working on the first Propeller. The second Propeller is unallocated so I am pretty confident the board has full functionality. Hopefully soon we'll have the ROM image for the SBC that allows booting directly with the PropIO and uses the microSD as a block device.

I've built my board up and it is basically done except I need to build a serial programming interface cable and program the Propeller. Hopefully I can do that tonight.

Things are definitely looking up for this project. What is neat is the PropIO at least in theory could be a complete computer when paired with the N8VEM SBC. Using a direct connection instead of the ECB backplane, the SBC has CPU, RAM, ROM, serial, parallel, and RTC and the PropIO bring console VGA and PS/2 keyboard and also the microSD for removeable mass storage block device. As I understand it the microSD is also mountable on PCs so you can use Linux or Windows to inspect the contents. The CP/M block device appears as a file in the microSD FAT file system.

You don't necessarily need an N8VEM SBC since really any Z80 system could use this board easily. All it would need is an ECB to CPU shim board & cable. I believe the PropIO could easily be adapted and mounted inside a Kaypro, Tandy, or other Z80 based microcomputer with little or no modification. It would require software support on the host platform.

I have plenty of PCBs available so if anyone wants to build their own please let me know. Thanks and have a nice day!

Andrew Lynch
 
Hi! I built my own PropIO PCB version this weekend and it works great! I had to make some adjustments to the serial programming interface but other than than it boots up just like the prototype. Since the PropIO connects directly to the SBC Z80 CPU without going through a UART the display is crazy fast. I used the TYPE command to print out a long assembler file and it flew by the display just like a PC. It was weird seeing the Z80 SBC moving so fast!

The other N8VEM builder is working on the microSD CBIOS and ROM image. He has it working on his PCB PropIO and it uses the same drive image file format as the Propeller based *Blade CP/M projects. I am really looking forward to seeing this board in action.

I posted some recent photos of my PCB PropIO build on the N8VEM wiki in the DWM-PropIO folder.

Also this weekend was good progress on the N8VEM 6809 computer. The 6809 host processor with IO mezzanine installed is now running CUBIX. That is interesting! An N8VEM builder is interfacing the DSKY front panel display and keyboard to the 6809 computer. With better debugging capability it should help increase the amount of software available for it.

It was a good weekend for the N8VEM project! Thanks and have a nice day!

Andrew Lynch
 
Hi All! This weekend I finally got to write up the schematic and PCB layout for the N8VEM SCG board. This board will plug into the ECB and provide color graphics and sound. It has a TMS9918 color graphics chip which includes sprites and also a AY-3-8910 sound chip with joystick and paddle interface.

A small group of N8VEM builders have been working on this board for a while now in fits and starts. I have built a partial prototype myself and know the TMS9918 color graphics part should work fine. Another builder prototyped the AY-3-8910 sound chip and another designed the combined board. The N8VEM SCG board will have both chips and the design is coming along nicely.

With some luck it should finish route optimization soon and with some cleanup revisions should be ready for manufactured PCBs. Once it is available we can use it for old school computer games like those for the original MSX. Things like Space Invaders are certainly possible.

If you have interest in building your own home brew computer with classic 1980's color graphics and sound contact me.

Thanks and have a nice day!

Andrew Lynch
 
Wow...

Wow...

Andrew, my hat goes off to you and all the others who have contributed to the N8VEM project.

I'm truly impressed. :)

I think I should be assembling and building an N8VEM system myself, both for fun and to get up to speed on computer design. I actually studied computer electronics at college, before switching majors to basic IT (software engineering, the high level stuff) when that didn't work out. Seeing all these cool hobby projects made that itch that I used to have in those younger days come back. Getting my hands dirty with low level hardware again. :)

Of course, I grew up in the 16 bit era, so I feel a lot of nostalgia with that in particular. That's why I was wondering if there were perhaps also plans to design and develop a 16 bit SBC kit ("N16VEM" ???) in a similar non-commercial hobbyist fashion.

I guess the most obvious CPU choice would probably be the 68000, because of its flat memory model, forward compatible design decisions, the high availability of compatible subsystem chips, and a well-documented open hardware architecture (VME). Also, it was pretty much the most popular 16 bit architecture in home computing.

Of course I understand that a 16 bit SBC would be much more complicated, if only because of the higher amount of interconnect lines on the board, not to mention possible endianness issues between components.

You mentioned the possibility of interfacing the N8VEM board with an 68008 board through a 8255 interface, but what I'm proposing is an actual from-the-ground-up 16 bit SBC design.

Would something like that be feasible in the same fun hobbyist fashion, without it growing too complicated?

I know I'd most likely have to play around with N8VEM myself first, but as I said, the 16 bit era happens to have a special place in my heart.
 
Hi! Thanks!

Extending the N8VEM project to 16 bit is actually being done in a couple of ways. The first is a 16 bit SBC for the ECB. At least one builder is working on an 8088 based ECB SBC. The ECB standard is actually 16 bit and the N8VEM ECB backplane supports 16 bit operation. The current SBC is 8 bit only as are all the peripherals. However, a 16 bit SBC should still be able to access the existing peripherals. I haven't discussed the 8088 project with the builder recently but last time I checked there was a schematic available and prototyping underway.

The other 16 bit expansion is coming by way of the S-100 boards in development. I am working with John from S100Computers.com to make a series of S-100 boards. Currently there are several S100 boards; backplane, regular prototyping board, buffered prototyping board, IDE, Parallel ASCII keyboard. Two more boards are in build and test and will be available soon; SRAM and Front Panel Bus Monitor. There are more boards in work at the moment; Z80 CPU and EPROM. Once those are complete we are planning on some 16 bit CPU boards starting with 8086, etc and some other peripherals. The S-100 boards we have are already 16 bit IEEE-696 compatible.

I really hadn't considered 68K very much other than some exploration and investigating. There is so much going on with the ECB and S-100 boards I really hadn't had time to do much with it yet. As for VME, I hadn't considered that either. Normally I had not associated VME with homebrew electronics although I see it may be possible. My personal interest has been mostly in the ECB and S-100 bus machines.

http://www.qsl.net/pe1jpd/vme/68020sys.htm

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

Andrew Lynch
 
Hi Andrew,

It's great to hear that the ECB backplane is already 16 bit ready! This should be interesting for future projects. An 8088-based SBC sounds awesome as well. But the 8088 has an 8 bit data bus, so it wouldn't require a 16 bit ECB SBC either, right? Or did you mean 8086?

The reasons why I proposed the 68000 and not the 8086 were the more elegant flat memory architecture of the former (no 64K segmentation kludge) and the fact that it was used in pretty much every 16 bit home computer except for the IBM PC and the Acorn Archimedes. Speaking of the Archimedes, perhaps a 16 bit ARM CPU could also be an interesting basis for a 16 bit ECB SBC. :)

But again, I'm becoming more and more convinced that I should first try and build an N8VEM board before I even think of tackling a 16 bit project. I would gain a lot more valuable insight that way first.
 
Hi! Yes, the ECB supports 8 or 16 bit modes. The 8088 SBC the builder is working does support an 8 bit data path but there have been 8086 and even 68K ECB SBC and/or CPU boards in the past. There are some great articles in C'T Projekt (German hobbyist magazine) from the 1980's with examples.

You are certainly welcome to join the N8VEM home brew computing project whether you build or not. It is really a discussion group that focuses on home brew computers. Some people build their own boards and others just build from the PCBs. I will gladly help you make manufactured PCBs of any prototype boards you get working. It would be very neat to have a 68K SBC and certainly a welcome addition.

One builder is adapting the 6809 host processor with IO mezzanine board to interface to the ECB peripherals. That way the DiskIO board and VDU can be used directly on the 6809 computer. It shows that even though the ECB is highly Z80 centered you can still readily adapt Motorola style peripherals to use ECB interface. If you design your 68K SBC to use the ECB you can leverage the existing N8VEM peripherals to add to your project quickly for disk and video expansion.

Please feel free to join us on the N8VEM project!

Thanks and have a nice day!

Andrew Lynch

PS, the N8VEM SCG board is nearly ready. It is a color graphics and sound board with TMS9918 color graphics and AY-3-8910 sound generator. It also has joystick and paddle interfaces so this should be interesting!
 
lynchaj said:
PS, the N8VEM SCG board is nearly ready. It is a color graphics and sound board with TMS9918 color graphics and AY-3-8910 sound generator. It also has joystick and paddle interfaces so this should be interesting!
Click to expand...

Hi! The N8VEM SCG PCBs have arrived! If you are interested in building one please contact me. The PCBs are available for the usual N8VEM $20 each plus shipping ($2 in the US and $5 elsewhere). These are really nice looking boards and should be a lot of fun. I've already sent out a couple of PCBs to the builders who've helped with its design and prototyping so hopefully we'll see some photos before too long. As I recall, one of the builders had a "space invaders" type demo game in the works.

If you have any questions about the N8VEM home brew computer project or would like boards you can join us on the N8VEM mailing list and the wiki. You can also email me at mailto:LYNCHAJ@YAHOO.COM?subject=N8VEM

Thanks and have a nice day!

Andrew Lynch
 
Hi! I just heard on the Kim Komando show there is a website (etsy.com) just for selling home crafted items so I am going to try it with the N8VEM home brew computer SBC PCB.

http://N8VEM.etsy.com

If anyone is interested in getting an N8VEM SBC PCB, give the etsy site a try and tell me how you like it. If it works OK I may start selling the other N8VEM boards there as well.

Thanks and have a nice day!

Andrew Lynch
 
Hi! Its been a while and I am still looking for hobbyists interested in building their own home brew Z80 CP/M computer. Many things have happened since June so here is a quick summary.

The new N8VEM SBC V2 PCBs have finally arrived. This SBC is functionally similar to the original N8VEM SBC but has many improvements and corrections. The board has had a respin and includes features for DS1210 NVSRAM controller and bank switching for CP/M 3.0 and MP/M support. Also added many configuration jumpers to allow a much wider variety of SRAM, EPROM, and Flash memory devices. The first PCBs have gone to the builders for build and test although I do have a few remaining boards. The N8VEM ECB Eurocard PCBs are $20 each.

In addition, there are several new mini-boards available such as the PPIDE which allows direct connection of IDE/CF devices to the parallel expansion port. This is very handy for low cost expansion without using the ECB backplane. One of the N8VEM builders has made drivers for CP/M and code is on the wiki.

Also there is a new Juha SD mini-board which can be directly connected to the N8VEM SBC and allows the use of standard SD memory for CP/M drives. There is code on the N8VEM wiki for this mini-board.

Finally there is a new ECB to Z80 socket adapter mini-board. This lets you connect any N8VEM ECB peripheral directly into a socketed Z80 computer like a Kaypro, Spectravideo, etc. This works amazingly well and allows expansion of non-N8VEM vintage computers using N8VEM peripherals like PropIO, DiskIO, etc.

All the mini-boards are $5 each plus $1 shipping in the US and $3 elsewhere.

Please contact me at LYNCHAJ@YAHOO.COM if interested. Thanks and have a nice day!

Andrew Lynch
 
Hi! If anyone would like to make their own home brew computer this would be a good time! There are too many updates to even describe here so I'll just leave them on the N8VEM mailing list and wiki.

I have many PCBs ready to go for any do it yourself hobbyist builders. This is a fun and exciting project and I find myself falling behind as there are so many things happening these days.

Please contact me if you would like some PCBs. Thanks and have a nice day!

Andrew Lynch
 
Hi! Several of the N8VEM builders are working on the new SBC-188 PCB which is a completely new board. It uses an 80C188 rather than a Z80 for a CPU and has the full suite of peripherals you'd expect like parallel port, serial port, RTC, and a WD37C65 floppy disk controller. It has its own RAM and ROM so it works both in standalone mode or as an ECB bus controller to access the other peripheral boards.

It is a neat project and the BIOS development is underway right now in case anyone would like to get in on it. I think the plan is to either run FreeDOS or CP/M-86 on it depending on how it goes. Maybe both but in either case the SBC is explicitly *not* PC compatible so it won't ever be just another PC/XT clone board.

There are several of the PCBs left so if you are interested please see me and you can get one of the remaining boards. I have the 80C188 CPU and WD37C65 FDC ICs on hand in case anyone wants those. The SBC-188 is part of the N8VEM project and is intended to be an alternate SBC to go along with the Z80 and 6809 projects we've been working on.

Thanks and have a nice day!

Andrew Lynch

PS, this weekend I ordered more SBC V2 (Z80) and new ECB backplane PCBs so they should be here in about three weeks or so.
 
Hi! I was reading on the forum someone mentioned the Jupiter ACE and it started me thinking. Just for entertainment purposes what would be a good mix of features for a stand alone computer system that builders could make themselves. Something all in one like the Commodore 64, Atari, Jupiter ACE or an MSX computer. It should be capable of fun games and still able to do basic applications while not being too expensive or difficult to make. Not a PC or other vintage home computer clone but a new design along the 1980's home computer style.

For example, a single board design with a 80C188 CPU, RAM, ROM, UART, parallel port, RTC and add a WD37C65 FDC chip. Add TMS9918 for color graphics and AY-3-8910 for sound. Use a PS/2 keyboard and joysticks for input and SD for mass storage and an expansion bus for peripherals. Power supplied by 9VDC wall wart.

The above would be a certainly doable using the existing N8VEM designs; the SBC-188 for core CPU and SCG board for color graphics and sound. Add a pair of 8 bit input and output ports for SD and PS/2 keyboard. That wouldn't even be a large PCB -- probably on the order of 200x160mm (double wide Eurocard) size.

It's something to think about. Thanks and have a nice day!

Andrew Lynch
 
I've actually been pondering just such a thing lately. I'd definitely go with the Atari/Amiga-style port for joysticks. AY-3-8910 isn't a bad sound chip, but it's not a particularily good one; on the other hand, the ones with more oomph, like the OPL series or the SID, tend to be harder to come by. I wonder how difficult it would be to implement something like the Konami SCC in a programmable-logic device...
 
Hi! Just to update recent developments; we are working on a home computer much like the one described. You can see progress here. I have the draft PCB in trace routing optimization at the moment. It will be there for several weeks at least before ready for initial prototypes.

http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=Home Computer

The design is roughly as described as above although the CPU is now Z8S180. It is much like the 80C188 although 8 bit only. It is quite fast though and in theory capable of clock rates of 33 MHz. I do not think that is realistically achievable with inexpensive 2 layer PCBs although it remains to be seen.

Also, if you were interested in a plain 80 column monochrome text video board, I just received a new batch of the respin VDU PCBs. They are much cleaner than the original VDUs and have more common 5x2 connectors for the PS/2 keyboard and mouse connectors rather than the 4x2 connectors.

Comments, questions, review, etc are welcome as always.

Thanks and have a nice day!

Andrew Lynch
 
Yes, interested!

Yes, interested!

lynchaj said:
Hi! Its been a while and I am still looking for hobbyists interested in building their own home brew Z80 CP/M computer. Many things have happened since June so here is a quick summary.

The new N8VEM SBC V2 PCBs have finally arrived. This SBC is functionally similar to the original N8VEM SBC but has many improvements and corrections. The board has had a respin and includes features for DS1210 NVSRAM controller and bank switching for CP/M 3.0 and MP/M support. Also added many configuration jumpers to allow a much wider variety of SRAM, EPROM, and Flash memory devices. The first PCBs have gone to the builders for build and test although I do have a few remaining boards. The N8VEM ECB Eurocard PCBs are $20 each.

In addition, there are several new mini-boards available such as the PPIDE which allows direct connection of IDE/CF devices to the parallel expansion port. This is very handy for low cost expansion without using the ECB backplane. One of the N8VEM builders has made drivers for CP/M and code is on the wiki.

Also there is a new Juha SD mini-board which can be directly connected to the N8VEM SBC and allows the use of standard SD memory for CP/M drives. There is code on the N8VEM wiki for this mini-board.

Finally there is a new ECB to Z80 socket adapter mini-board. This lets you connect any N8VEM ECB peripheral directly into a socketed Z80 computer like a Kaypro, Spectravideo, etc. This works amazingly well and allows expansion of non-N8VEM vintage computers using N8VEM peripherals like PropIO, DiskIO, etc.

All the mini-boards are $5 each plus $1 shipping in the US and $3 elsewhere.

Please contact me at LYNCHAJ@YAHOO.COM if interested. Thanks and have a nice day!

Andrew Lynch
Click to expand...

lynchaj said:
Hi! If anyone would like to make their own home brew computer this would be a good time! There are too many updates to even describe here so I'll just leave them on the N8VEM mailing list and wiki.

I have many PCBs ready to go for any do it yourself hobbyist builders. This is a fun and exciting project and I find myself falling behind as there are so many things happening these days.

Please contact me if you would like some PCBs. Thanks and have a nice day!

Andrew Lynch
Click to expand...
Hello there.
I was searching for some Z80 information and came across this thread.
As it so happens I am looking to build a Z80 based system as I have obtained some Z80 MPU's.
I will of course get around to reading the whole thread in due course, but until then can you please let me know what PCB's are still available, some information on what items can be fitted /functions and of course the prices.
Now I live in the UK, so please also give me some idea of how much the cost of post / shipping would be.
Thanks, Mark
 
1024MAK said:
Hello there.
I was searching for some Z80 information and came across this thread.
As it so happens I am looking to build a Z80 based system as I have obtained some Z80 MPU's.
I will of course get around to reading the whole thread in due course, but until then can you please let me know what PCB's are still available, some information on what items can be fitted /functions and of course the prices.
Now I live in the UK, so please also give me some idea of how much the cost of post / shipping would be.
Thanks, Mark
Click to expand...

Hi!

I have all the N8VEM ECB Eurocard PCBs on hand. There are twelve Eurocard (160 x 100 mm) PCBs available; the N8VEM SBC V2, the ECB backplane, the ECB bus monitor, the ECB prototyping board, the Disk IO board, the Zilog Peripherals board, the Video Display Board, PropIO, SCG, SBC-188 V2 (PCBs pending), 4MEM (SBC-188 4 MB SRAM expansion) and ECB Cassette Interface.

The three 6809 standalone computer boards available in the Eurocard (160 x 100 mm) format; the 6809/6802/6502 host processor, the IO mezzanine, and ECB bus bridge. A redesign of the 6809 host processor board has completed and the new version will supports 6502 and 6802 CPUs in addition to the 6809. All Eurocard ECB format PCBs are $20 plus shipping which is $2 per board in the US and typically $5 per board overseas.

There are four "mini-board" PCBs available; Juha SD, PPIDE, ECB to Z80 socket shim, and AT2XTKBD. All mini-board PCBs are $5 plus shipping which is $1 per board in the US and typically $3 per board overseas.

Thanks and have a nice day!

Andrew Lynch, 73 de N8VEM

PS, if you haven’t already please join us on the N8VEM mailing list and wiki

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

http://groups.google.com/group/n8vem
 
Hi
There are many N8VEM PCBs available to support your own home brew computer or even modify existing vintage computers.

http://n8vem-sbc.pbworks.com/w/page/35044530/PCB Inventory

All the design information is free and publicly posted (schematics, PCB layout, KiCAD EDA files, software, parts lists, photos, etc)

Please contact me at LYNCHAJ@YAHOO.COM or send a PM if interested.

Thanks and have a nice day!

Andrew Lynch
 
Hi

One of the N8VEM builders wrote a draft magazine article that provides a great overview of the N8VEM home brew computing project. It is so good I thought maybe the hobbyists here would like to read it and better understand what we are doing.

http://n8vem-sbc.pbworks.com/w/file/61597682/N8VEM article.doc

Most of these PCBs I have physically on the shelf waiting to go to builders. Others will be reordered and builders always have the option of getting their own based on the information on the website.

http://n8vem-sbc.pbworks.com/w/page/35044530/PCB Inventory

Please send me an email if interested. Thanks and have a nice day!

Andrew Lynch
 
You must log in or register to reply here.
Back
Top