Search found 162 matches

by Bill H
Thu May 20, 2021 5:15 pm
Forum: Hardware
Topic: ZX81 Keyboard
Replies: 4
Views: 522

Re: ZX81 Keyboard

Diode D1 and it’s connections. Also test between it’s cathode (the end with the stripe) and Z80A pin 1. And between it’s anode and the relevant pin of the eight pin keyboard ribbon connector. Mark Thanks Mark that was it. The D1 connector for the keyboard was no longer connected to the diode. I jus...
by Bill H
Wed May 19, 2021 8:54 pm
Forum: Hardware
Topic: ZX81 Keyboard
Replies: 4
Views: 522

Re: ZX81 Keyboard

1024MAK wrote: Wed May 19, 2021 8:50 pm Diode D1 and it’s connections. Also test between it’s cathode (the end with the stripe) and Z80A pin 1. And between it’s anode and the relevant pin of the eight pin keyboard ribbon connector.

Mark
That what I was thinking but I wanted to get a second opinion
by Bill H
Wed May 19, 2021 8:02 pm
Forum: Hardware
Topic: ZX81 Keyboard
Replies: 4
Views: 522

ZX81 Keyboard

HI all - I have a perplexing issue, at least to me. I have a ZX81 where the keys 1 - 5 are not working. I pulled it apart, trimmed the membrane etc and they still don't work. If I use my multimeter I can tell that they are working though. With cover off and no power I touch the row and column solder...
by Bill H
Sun Apr 18, 2021 7:49 pm
Forum: Hardware
Topic: TS 1000 Composite Mod
Replies: 3
Views: 383

TS 1000 Composite Mod

HI All - I'm stumped on what could be causing my issue. I am trying to add composite out to the TS 1000 basically following this https://www.classic-computers.org.nz/blog/2016-01-03-composite-video-for-zx81.htm And this https://www.bytedelight.com/?page_id=3560 I am using the correct transistor (2N3...
by Bill H
Thu Apr 01, 2021 3:04 pm
Forum: WANTED
Topic: Memotech 16K
Replies: 2
Views: 1750

Memotech 16K

HI All does anyone have the manual for the 16k memotech memopak?

Bill H
by Bill H
Fri Jan 29, 2021 9:34 pm
Forum: Emulators
Topic: A new ZX81 Emulator
Replies: 13
Views: 10154

Re: A new ZX81 Emulator

Hi all - I am back to working on this, its going along nicely but I am stumped. After I load a .P file to the proper location in memory (along with all the correct system variables) where should I jump into the ROM? I am only making use of the "NAME" routine to get the name they passed in LOAD " " ...
by Bill H
Fri Jan 29, 2021 9:20 pm
Forum: Emulators
Topic: A new ZX81 Emulator
Replies: 13
Views: 10154

Re: A new ZX81 Emulator

Hi all - I am back to working on this, its going along nicely but I am stumped. After I load a .P file to the proper location in memory (along with all the correct system variables) where should I jump into the ROM? I am only making use of the "NAME" routine to get the name they passed in LOAD " " t...
by Bill H
Thu Feb 27, 2020 3:13 pm
Forum: Emulators
Topic: A new ZX81 Emulator
Replies: 13
Views: 10154

Re: A new ZX81 Emulator

Ok so I have the keyboard working great as long as I wait for a key on the Adam. I am not sure what col / row I should return if no key is pressed. I see it starts out with H = FFh and L = FFh and I tried to return that is there is no key press but the ZX81 doesn't like it. Any tips on this? Edit: I...
by Bill H
Tue Feb 25, 2020 11:40 pm
Forum: Emulators
Topic: A new ZX81 Emulator
Replies: 13
Views: 10154

Re: A new ZX81 Emulator

Problems you might get 1) ROM-bug. Can you protect #0000-#1FFF against writing? If not, first addresses will be overwritten. 2) Reading IN-port (result can be different from machine you run or ZX81. Can be fixed with a scan and RST. 3) My games with "hidden" data on screen, can be emulated with cor...
by Bill H
Tue Feb 25, 2020 7:50 pm
Forum: Emulators
Topic: A new ZX81 Emulator
Replies: 13
Views: 10154

Re: A new ZX81 Emulator

Thanks again - I see it is storing it in LAST_K but I do not have any change on the screen so I have to dig a little deeper. This is what the system variables look like:
system variables.PNG