Search found 1768 matches

by 1024MAK
Sun Nov 19, 2017 7:49 pm
Forum: Welcome Area
Topic: Hello Everyone
Replies: 5
Views: 60

Re: Hello Everyone

Hello Rdube123

Welcome to our forum.

I hope you like it.

Please join in any discussions you are interested in. The life blood of forums, is keeping the regulars awake by prodding them with questions :mrgreen:

Mark
by 1024MAK
Sun Nov 19, 2017 7:46 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 58
Views: 1279

Re: ZX81 rebuild

I got new sockets from Sell My retro:- https://www.sellmyretro.com/offer/details/3473 They have four legs rather than the three in use on the zeddy. Do i just fold the unwanted one under or do i need to remove it? Currently I have reused an old one. Remove it or just cut it off. It's not fitted on ...
by 1024MAK
Sat Nov 18, 2017 11:44 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 58
Views: 1279

Re: ZX81 rebuild

El cheapo logic probe for 5V TTL logic... If you have a spare 74LS14 or 74HCT14 logic chip, connect a test probe to a resistor (100 ohms to 180 ohms for a 74LS14, 330 ohms to 820 ohms for a 74HCT), then connect to any of the chips input pins. On the relevant output, connect a RED LED via a 390 ohm o...
by 1024MAK
Sat Nov 18, 2017 5:55 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 58
Views: 1279

Re: ZX81 rebuild

It's not polarised, any way is fine. Except upside down :lol: If you have a 'scope or logic probe, check Z80 address lines A14 and A15. Also is you have a 'scope, test the video/TV output pin to see if it is switching between the three levels (high = white, "mid-way" = black and low= low part of th...
by 1024MAK
Fri Nov 17, 2017 1:29 am
Forum: Hardware
Topic: Heat sink on Spectrum ULA - is there any benefit?
Replies: 16
Views: 190

Re: Heat sink on Spectrum ULA - is there any benefit?

Chances are it would not get a huge amount of usage. Certainly never more than a couple of hours at a time anyway. Should not be a problem then ;) Heat level inside will be a lot lower than if used as originally manufactured (due to the switching regulator replacing the 7805), so the ULA should be ...
by 1024MAK
Thu Nov 16, 2017 6:29 pm
Forum: Hardware
Topic: Heat sink on Spectrum ULA - is there any benefit?
Replies: 16
Views: 190

Re: Heat sink on Spectrum ULA - is there any benefit?

It depends on a number of factors. First, the different issue ULAs produce different amounts of heat. The early types ran hot. The later ULAs used a lower power design, so run cooler (well, warm instead of hot). Second, yes the rubber key has poor ventilation. The plus keyboard is much better. Back ...
by 1024MAK
Wed Nov 15, 2017 1:41 pm
Forum: Hardware
Topic: A zeddy Christmas?
Replies: 6
Views: 113

Re: A zeddy Christmas?

The unicorn that Sir Morris promised with every release of the ZXpand. :lol: More seriously I already have my presents early in the shape of Andy Reas' UDG unit and UDG designer software and Sir Morris' MIDI firmware and MIDI player software for the ZXpand+. Nice low lit room plus a good single mal...
by 1024MAK
Tue Nov 14, 2017 9:15 pm
Forum: Development
Topic: DEV-SNIP #1 - Input
Replies: 26
Views: 336

Re: DEV-SNIP #1 - Input

sirmorris wrote:
Tue Nov 14, 2017 8:59 pm
Even getting the joystick value IN() isn't the end of it - most of the problem using joysticks from BASIC is the lack of bitwise logic :(
Aye, but that problem has always been a limitation of both ZX81 and ZX Spectrum BASIC. It also makes reading the keyboard directly a pain.

Mark
by 1024MAK
Tue Nov 14, 2017 7:48 pm
Forum: Development
Topic: DEV-SNIP #1 - Input
Replies: 26
Views: 336

Re: DEV-SNIP #1 - Input

:D Glad to see my trap worked first time Mark :lol: If anyone wants to donate an interface for testing purposes..! ;) I'll assume you missed it the first time. :D @Charlie If you genuinely need a j/stk interface I have a pukka Kempston speccy one and a no-name ZX81 interface with ZX81 edge connecto...
by 1024MAK
Tue Nov 14, 2017 11:49 am
Forum: Development
Topic: DEV-SNIP #1 - Input
Replies: 26
Views: 336

Re: DEV-SNIP #1 - Input

It's currently specialised for ZXpand but it's easily updated to work with, for example, Chroma or (I still don't believe they exist) Kempston ;) Before finding this forum, I didn't think any users of ZX81's existed anymore.... :roll: Let alone that there was new software and hardware being develop...