Search found 2264 matches

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: 2138

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...
by PokeMon
Tue Nov 10, 2020 2:46 pm
Forum: SALES
Topic: The ZXpand and the Minstrel situation
Replies: 5
Views: 3828

Re: The ZXpand and the Minstrel situation

Yes, the ZXpand itself is the same, but what I was trying to say, was that at one time a package of a ZXpand, including the relevant ROM for use with a ZX80 and the ribbon extender cable we’re being sold for use with ZX80 computers. Although I think the ribbon extender cable was also available sepa...
by PokeMon
Tue Nov 10, 2020 2:44 pm
Forum: Hardware
Topic: Flaky ZX81
Replies: 31
Views: 5958

Re: Flaky ZX81

That`s why I advised to do a manual reset after power-on.
I guessed that there could be a timing mismatch.
Solution would be to choose a larger capacitor than 1uF as reset cap.
by PokeMon
Sun Nov 08, 2020 12:45 pm
Forum: Hardware
Topic: How to power off the ZX81 correctly
Replies: 15
Views: 3045

Re: How to power off the ZX81 correctly

Always this way PRINT "SHUTDOWN IN PROGRESS" - wait 5 seconds and pull the 3.5mm plug out.
Be sure to wait at least 5 seconds to get the heads of the ULA in park position. 8-)

Funny question by the way - you made my day. :lol:
by PokeMon
Sun Nov 08, 2020 12:40 pm
Forum: ZX BASIC
Topic: FXY Function
Replies: 11
Views: 3562

Re: FXY Function

FXY is not a function, it is simply a numeric variable (name) in the listing. And it is not an array.
by PokeMon
Sat Nov 07, 2020 10:33 pm
Forum: Hardware
Topic: Flaky ZX81
Replies: 31
Views: 5958

Re: Flaky ZX81

Not sure I’m brave enough to try and do a reset! Looking back at your pic, the reset capacitor was replaced. Normally it is an bigger axial, no radial type. Are you sure there is enough distance between the board tracks and the capacitor legs as they are quite long. Just an idea. Maybe worth to iso...
by PokeMon
Sat Nov 07, 2020 2:57 pm
Forum: Hardware
Topic: Flaky ZX81
Replies: 31
Views: 5958

Re: Flaky ZX81

I would be carful with the Chroma Interface when using other components than the original. It is very timing sensitive. Better use a plain RAM expansion when you are unsure about the internal RAM. What happens after startup with a manual reset instead of powering off ? You could just use any tactile...
by PokeMon
Sat Nov 07, 2020 12:56 am
Forum: Hardware
Topic: Flaky ZX81
Replies: 31
Views: 5958

Re: Flaky ZX81

When normal boot happens - does it work properly then ?
Is there maybe a cold or broken solder joint ?
What happens when slightly knocking on the board or the chips with a screwdriver or similar ?
by PokeMon
Thu Nov 05, 2020 10:46 pm
Forum: Development
Topic: QR Code version 1
Replies: 14
Views: 7985

Re: QR Code version 1

Version 11 needs 61x61 pixels to render, the largest one needs 149x149. This page has detailed information about all QR Code sizes, capacities etc. Then you could make a bigger version for ZX81 as well as is supports a resolution of 256x192 pixels. With HRG driver like used by Z88dk. In general the...
by PokeMon
Thu Nov 05, 2020 10:30 pm
Forum: Welcome Area
Topic: Hi!
Replies: 6
Views: 2006

Re: Hi!

Welcome aboard ! 8-)