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by Martin A
10 Jan 2021 20:31
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 89
Views: 25576

Re: Another Home-Brew - Z180

Are you running your Z180 in HD64180 I/O mode or Z80 compatible I/O mode ?

If the IOC bit in the operatiom mode control register (Bit 5 of &3E) is cleared, and it's det by default , *IORQ and *RD are delayed to the rising edge of T2 just like *WR and the Z80 way of things.
by Martin A
02 Jan 2021 20:01
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 89
Views: 25576

Re: Another Home-Brew - Z180

Have you got one of these https://www.amazon.co.uk/Hobby-Componen ... 00DAYAREW/ in any shape or form ?

It might help you work out what's going on. It uses the open source PulseView software so should work with Linux.
by Martin A
24 Dec 2020 19:29
Forum: NEW HARDWARE
Topic: RS232?
Replies: 3
Views: 257

Re: RS232?

I would be tempted to use a Z80 SIO/0 and one or more level shifters from the MAX232 family rather than replicate the original design the old Z80 DART and the MC1488/1489. For the MTX plus I put the SIO/0 and a RS232 to USB adaptor on the I/O baord. As to how well that works it's anyone's guess as I...
by Martin A
21 Dec 2020 20:58
Forum: OFF TOPIC
Topic: Coprocessors for BBC micro
Replies: 2
Views: 155

Re: Coprocessors for BBC micro

It's not totally off topic. I did have a look at the project a while back, to see if it was possible to do a MTX coprocessor the same way. It the time I couldn't find any of the regular Pi stockists that had the pi Zero in stock and then sort of forgot the idea. The host side hardware on the MTX pro...
by Martin A
19 Dec 2020 15:20
Forum: REMEMOrizer
Topic: Case/Extension Cable?
Replies: 26
Views: 6826

Re: Case/Extension Cable?

I don't suppose anyone has a spare case & keyboard? Why gut a working MTX ? There aren't THAT many working MTXs out there but they're likely to be more common than just cases & keyboards. There's plenty of room to mount a PI in the internal RAM/RS232 area. Use replacement RS232 covers and maybe the...
by Martin A
12 Dec 2020 16:02
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 89
Views: 25576

Re: Another Home-Brew - Z180

Is there sufficient CPLD resources to allow a "manually" opperated clock in addition to the main one? So that rather than bitbanging the whole SPI interfase, you just have to bitbang the clock for the initial setup period. I'm thinking a 2 bit I/O port when the shift register clock is (CLK AND Bit1)...
by Martin A
11 Dec 2020 17:38
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 89
Views: 25576

Re: Another Home-Brew - Z180

IS that workng with the "original" level shifters Or the daughter board ?
by Martin A
29 Nov 2020 14:15
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 89
Views: 25576

Re: Another Home-Brew - Z180

IT was just a suggestion for testing, I didn't realise it wss the low that was the issue, I'd asumed it was the high. One thing I've just spotted looking at the data sheet. VCCA seems to be on pin 2, and VCCB on pin 19. The schematic shows Pin 1 and pin 20 respectively, do the adaptor boards take ca...
by Martin A
28 Nov 2020 19:49
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 89
Views: 25576

Re: Another Home-Brew - Z180

Can you "get away" with just using current limiting resistors, at least for testing ?

The VIH minimum for the Z180 is 2v according to the datasheet I have. Which is witin the Propeller capabilities as that should have a VOH minimum of 2.8.
by Martin A
17 Nov 2020 21:21
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 89
Views: 25576

Re: Another Home-Brew - Z180

That's impressive, it'll really interesting to see how it progresses.