Z80 Clones

318 views
Skip to first unread message

Martin Niec

unread,
Apr 24, 2021, 10:52:54 AM4/24/21
to RC2014-Z80
Hi guys,
have you tried any of Z80 clones in your RC2014? I have come across some by snooping around Ebay.
Just asking before I make more research and consequential and inevitable purchases  :)

Please let me know if pinout is the same?
Mart

Alan Cox

unread,
Apr 24, 2021, 12:17:57 PM4/24/21
to rc201...@googlegroups.com
On Sat, 24 Apr 2021 at 15:52, Martin Niec <marti...@gmail.com> wrote:
Hi guys,
have you tried any of Z80 clones in your RC2014? I have come across some by snooping around Ebay.
Just asking before I make more research and consequential and inevitable purchases  :)

The ones you've linked to are NMOS and except the Z80H variant also slow.  RC2014 uses a CMOS Z80 part.

NMOS Z80 will be very touchy with the CF adapter or any non CMOS (74HC/HCT) part on the board. If you are careful about that then it ought to work. The differences between the CMOS and NMOS Z80 are miniscule except for one undocumented instruction and a bug fix. The difference between the soviet ones and the original are also basically nil (it's possible to detect them by careful choice of instruction undocumented behaviour - but that equally goes for Zilog v some other official producers). I don't know if ROMWBW has the NMOS IRQ bug workaround but it probably doesn't need it either.

I have run NMOS non Z80 parts with RC2014 and by being careful about what goes on the bus. I've done it with 68008 and 6809 and a few others. So I would expect that if you drop the clock sufficiently for the part, and remember the baud rate will change if using an ACIA or SIO it ought to work - but you might need to switch to the PPIDE adapter or SD card bitbang and you might not get it to work with 10 cards in slots.

Alan

Spencer Owen

unread,
Apr 24, 2021, 12:46:47 PM4/24/21
to rc201...@googlegroups.com
I know at least a couple of people have used those clones on the RC2014 Classic. The only thing they had to change was the clock speed as they didn't like being run at the standard 7.3728Mhz. Running them at 3.6864Mhz (and serial at 57,600 baud) worked just fine though.

Spencer 

--
You received this message because you are subscribed to the Google Groups "RC2014-Z80" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rc2014-z80+...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/rc2014-z80/CAK9X0%2Bv9SrQLD_RYE9g%2Bi92ttifi1iJ8Eo6DG0%3Diux2W0ZYAuw%40mail.gmail.com.

Andrew Quinn

unread,
Apr 25, 2021, 8:14:21 PM4/25/21
to RC2014-Z80
I also went down that eBay rabbit hole and had a lot of fun building an "RC2014" type machine using a mix of East German and Soviet parts.

One thing to watch is the pin spacing is metric (2.5mm) rather than imperial (0.1" = 2.54mm) so 40 pin DIP parts won't work with machined IC sockets.  The dual swipe sockets are fine.

I built the machine from the following boards....

Processor Board with Soviet LEDs and DL004D (DDR version of 74LS04) to drive the LED.  Photo shows a Zilog Z80 but I run it with a UB880.


SIO Board using the UB8560 (DDR version of Z80 SIO/0) and DS8205D (DDR version of Intel P8205)


EPROM Board with КC573РФ2 2K EEPROM (Soviet version of the 2716), DL032D (DDR version of 74LS32) and DS8205D (DDR version of Intel P8205)  


RAM board with ZMD U6264 (DDR version of 6264 8K Static RAM), DL032D (DDR version of 74LS32) and DS8205D (DDR version of Intel P8205)  


Digital IO Board with Soviet LED, DL004D (DDR version of 74LS04), DL032D (DDR version of 74LS32) and DS8205D (DDR version of Intel P8205).  Photo shows a Siemens 8282A (German version of the Intel 8282 latch) but I run it with KR580IR82 (Soviet version of the 8282)


The full system comprises the CPU, SIO, ROM, 2 x RAM and Digital IO boards.

https://photos.app.goo.gl/DsgiySsh6SaFPQDi8 (SIO not installed in this photo).

Software wise, it is all made possible by Steve Cousins excellent "Small Computer Monitor" available on https://smallcomputercentral.wordpress.com/ ... because it fits nicely into 8K of ROM.

Why?  Because it was fun.  I am happy to put the board files on GitHub if anyone is interested in building their own.  The components are readily available from a few sellers on eBay.

william brown

unread,
Apr 26, 2021, 3:09:29 AM4/26/21
to rc201...@googlegroups.com
hi guys
               i am trying to send MIDI notes using the sio in rc2014 ,i have set up the inilisation according to the book "Z80 applications" but all i get is a pulse on my logic probe
led .no switching between red and green..i compiled it on ASM80 on line.can anyone help.ive set the clock to the midi frequency 31250. a 2meg /64.ok
i tried modifying steve cousins sio test programme.but the asm80 didnt like some syntax namely..CODE  .PROC Z80 .HEXBYTES .DATA..i dont know how to move forward
i have worked a lot with Z80 in the past ,but SIO is difficult to debug.thanks for any help.
bill brown

--
You received this message because you are subscribed to the Google Groups "RC2014-Z80" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rc2014-z80+...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/rc2014-z80/a9d3623a-0125-4354-be12-d63c95865084n%40googlegroups.com.
Reply all
Reply to author
Forward
0 new messages