Search found 2253 matches

by PokeMon
Wed Dec 09, 2020 10:05 pm
Forum: Hardware
Topic: Fixing inherited Sinclair ZX81
Replies: 34
Views: 4375

Re: Fixing inherited Sinclair ZX81

"Yeah dad I thought you said we were getting a PS5?" :lol: A ZX81 is better than any PS5. Black and white is the new color. Big pixels are better for the eyes. Membrane keyboard is a good training for the fingers. And with missing sound you better concentrate on the game. 8-) So what could be bette...
by PokeMon
Wed Dec 02, 2020 8:49 pm
Forum: ZX BASIC
Topic: Figure plotting trouble
Replies: 16
Views: 2150

Re: Figure plotting trouble

Maybe here are 2 ressources for you with 1k games for your interest:

https://sinclairzxworld.com/viewtopic.php?f=6&t=2349

http://www.rwapsoftware.co.uk/zx81/zx81_software.html
by PokeMon
Sat Nov 28, 2020 11:35 am
Forum: ZX BASIC
Topic: Figure plotting trouble
Replies: 16
Views: 2150

Re: Figure plotting trouble

XavSnap wrote: Sat Nov 28, 2020 5:19 am The 4 error point to a variable error, not setup... (LET COS=0)…
In this program SIN & COS are numerics functions.
Error 4 means out of memory.
How much memory is installed, Matt ?

Matt, I think it is a 1k problem.
What gives PRINT PEEK 16389 ?
Should be 128 (16k) not 68 (1k).
by PokeMon
Fri Nov 27, 2020 11:27 pm
Forum: Development
Topic: ZX21: CERAMIC RESONATOR
Replies: 11
Views: 1370

Re: ZX21: CERAMIC RESONATOR

I think Farnell has it cheap from Murata
https://uk.farnell.com/murata/cstls6m50 ... dp/2913670

Alternatively a 6.500 MHz crystal is not rare as well. Would be more accurate ...
by PokeMon
Thu Nov 26, 2020 9:13 pm
Forum: ZX Spectrum Lounge
Topic: Harlequin video modifications
Replies: 26
Views: 23576

Re: Harlequin video modifications

This resistor and capacitor add by Ingo from Germany, he said it help to make picture be in the middle of screen. Okay thanks. ;) But for me it is more Voodoo. The chip supports either composite video and s-video, so s-video output is wasted. Okay is no official connector for the signal aboard but ...
by PokeMon
Thu Nov 26, 2020 8:58 pm
Forum: Hardware
Topic: I started on my new ZX-81 replacement board (kit) ZX81+38
Replies: 37
Views: 26955

Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Yes, I guess this is all a matter of preference. :mrgreen:
by PokeMon
Thu Nov 26, 2020 8:53 pm
Forum: Development
Topic: ZX21 Project ZX81 Replacement PCB
Replies: 61
Views: 7162

Re: ZX21 Project ZX81 Replacement PCB

The AS 6C1008-55PCN is CMOS only so not great for a TTL Computer. You can use the 512K Byte big brother however and I do have some of those. Is there much software that needs more than 32K? You would, of course, need to add additional logic to get more than 16K working. A6SC1008 works great with TT...
by PokeMon
Sat Nov 21, 2020 12:07 am
Forum: Hardware
Topic: I started on my new ZX-81 replacement board (kit) ZX81+38
Replies: 37
Views: 26955

Re: I started on my new ZX-81 replacement board (kit) ZX81+38

A NAND gate with inverted inputs and inverted output is logically the same as an OR gate.
Personally I prefer using an OR symbol rather than an AND symbol with all inverted.
by PokeMon
Tue Nov 17, 2020 8:32 pm
Forum: Hardware
Topic: Trying to make a 32K mod on Zx81 together with other mods
Replies: 4
Views: 851

Re: Trying to make a 32K mod on Zx81 together with other mods

Did this board run before the modification with the other components or just a first try ? Maybe you just need another setting of trimmer R2 on the ZX8-CCB module as there is no Ferranti ULA inside but a rework (with possibly other voltage levels at the output). Just make a photo of the trimmers pos...