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Zeta SBC - Minimal, self-contained, N8VEM compatible Z80 SBC

Hello,

I'am intrested in 2 PCBs + one time the 4 ICs to build a ZETA SBC.
What are the complete price with shipping to Germany?

regards joerg
 
That would have been a lot cheaper than the one I used.

By the way, I completed my build of the Zeta some time ago, and it's a really neat SBC. I (and several others) have posted photos and build notes on the N8VEM wiki, at:

Main page: http://n8vem-sbc.pbworks.com/w/page/44366173/Zeta SBC
Photos (more in other users' directories): http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=Alex Jacocks

There's a new accessory board, called the ParallelPortPropellor, which provides VGA output, PS/2 keyboard, SD card storage, and a speaker. It is described here, and boards can be ordered from Sergey:
http://n8vem-sbc.pbworks.com/w/page/52472959/ParPortProp

- Alex
 
I got my board all soldered, I just haven't gotten the power supply finished (going for an AC plug & switch + power supply, as I'd rather not waste outlet space with another wall-wart, and I plan on putting this thing in a little case anyway.)
 
Okay, the completed board has been sitting around my apartment for way too long, and it's about time I got it all hooked up. I'm not quite clear on the last few details re: hooking up the power, though. As was suggested, I've got a Meanwell RS-25-5 and an AC plug/switch assembly. It's obvious that + and - on the SBC should go to V+/V- on the PSU, but it's not very clear which of the holes for the power plug V+ and V- are. Moreover, is one of them a separate ground? Does that need to be connected to the ground line on the PSU, or does the ground line on the PSU go to the ground blade on the AC plug?

Also, is there a good simple hack that could be done to add a simple timer interrupt to the system? I've been toying with the idea of building this into a homebrew MIDI sequencer/workstation, but that would require a reliable clock source...
 
Hi,

Power connector: The center (pin) of the power connector is +5V, the sleeve is ground (or -). You can use a multimeter to verify the polarity of your power supply before you connect it to the board. There is no separate ground.

Timer interrupt: I can't think about anything really simple. I guess you can connect a timer to /INT line through a 74LS06 open collector inverter. You can reuse the 74LS06 inverter gate that was intended for FDC, since BIOS doesn't use interrupts for FDC I/O. For timer you can use 8254, or Zilog Z80 CTC, or a simple impulse generator, for example a frequency divider fed with UART's 1.842 MHz frequency. If using a programmable timer it also will need to be connected to a system so you can program it. It might be connected either directly to Z80 bus, or through 8255 PPI (if you're not using it for ParPortProp or PPIDE).
 
Well, I mean which of the three holes in the board is +5V and which is ground; I didn't get a barrel connector since I was just planning on wiring it directly to the PSU (eventually I plan to put it all together in a case.)
 
Two of three pads are connected to the ground. You can actually find what pad is +5V and what pads are ground by looking at the traces. for example capacitor C29 connected between +5V and ground, and has polarity marked.
 
Okay. That's what it looked like, but I'm no expert at reading schematics or traces, so I wanted to be sure, rather than hook up the power and find out I was wrong by the smoke :D
 
Pleased to report it's up and running :) The cramped little connector array on the AC plug/switch assembly gave me more soldering trouble than the board ever did! But once that was all taken care of, it powered right up without issue, talks happily over the serial port, and boots into CP/M. Now I just gotta get working on a case...
 
Is there a simple way to get a custom build of the system ROM? I'd like to get VDE configured for a VT-100 emulation, and I'd also like to ditch some of the unnecessary files (the IDE stuff, for example) and put some other miscellany on the ROM disk in its place...
 
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