Search found 1536 matches

by Andy Rea
Mon Apr 22, 2019 12:13 am
Forum: Hardware
Topic: Composite mod done Zx81 great picture but somethkng is wrong
Replies: 14
Views: 210

Re: Composite mod done Zx81 great picture but somethkng is wrong

unless you really need the capacitor i'd ditch it... most modern tv's don't have any DC bias on the composite inputs.

regards Andy
by Andy Rea
Sun Apr 21, 2019 1:36 pm
Forum: Hardware
Topic: Composite mod done Zx81 great picture but somethkng is wrong
Replies: 14
Views: 210

Re: Composite mod done Zx81 great picture but somethkng is wrong

Don't let Moggy know but try a heatsink on the ULA...

BTW which composite mod did you do?

Andy
by Andy Rea
Sun Apr 21, 2019 1:38 am
Forum: Welcome Area
Topic: Hello all from Wellington, New Zealand
Replies: 3
Views: 97

Re: Hello all from Wellington, New Zealand

Welcome, hope you find some useful information.

Regards Andy
by Andy Rea
Sat Apr 13, 2019 3:04 pm
Forum: Hardware
Topic: ZX81 External Keyboard
Replies: 37
Views: 3858

Re: ZX81 External Keyboard

Hi

is this keyboard available yet ?

regards Andy
by Andy Rea
Fri Apr 12, 2019 10:37 pm
Forum: Hardware
Topic: Overclocking the machine
Replies: 3
Views: 128

Re: Overclocking the machine

Andy (a member here) has seriously overclocked a ZX81. However he was using his older ULA replacement module. With a standard Sinclair ULA, overclocking is difficult as you can’t change the frequency without messing up the screen display. Mark Slight correction, the older ULA could do 2X speed... m...
by Andy Rea
Mon Apr 01, 2019 7:07 pm
Forum: Hardware
Topic: TS1500 50Hz which resistor
Replies: 6
Views: 260

Re: TS1500 50Hz which resistor

Paul wrote:
Mon Apr 01, 2019 6:23 am
Hi Andy, I guess it would be possible internally as well?
Which bytes have to be changed?
Do you know how the channel 2/3 selection works? Maybe this could be (ab)used for ROM switching?
Kind regards Paul
Nice idea, worth looking into for sure.
by Andy Rea
Sun Mar 31, 2019 10:18 pm
Forum: ZX BASIC
Topic: what is the largest number that can be stored on a zx81
Replies: 10
Views: 401

Re: what is the largest number that can be stored on a zx81

lets assume we are going to use the whole 16K to store a single whole number dont want ony of the rounding loss business with floating piont numbers and exponents ( although the number you could store would be huge ) so we have 16384 * 8 bits to store our large integer (2^0 + 2^1 + 2^2 .... + 2^1310...
by Andy Rea
Sun Mar 31, 2019 10:04 pm
Forum: Hardware
Topic: TS1500 50Hz which resistor
Replies: 6
Views: 260

Re: TS1500 50Hz which resistor

Not certain it can be done that way, least i never was able on my ts1500, however you can use and external rom and hardcode it for 50hz

regards Andy
by Andy Rea
Thu Mar 14, 2019 5:58 pm
Forum: Hardware
Topic: Hello All & Dead ZX .. probably
Replies: 16
Views: 652

Re: Hello All & Dead ZX .. probably

McKlaud wrote:
Tue Mar 05, 2019 1:16 pm
Dishwasher would be better ;)
i had a commodore pet universal main board ( from a cbm 4032 machine) in the kitchen sink... my missus thought i'd gone nuts... works a treat and is clean to boot now :D :D
by Andy Rea
Thu Mar 14, 2019 5:54 pm
Forum: Software
Topic: Converting TAP to WAV files for Spectrum
Replies: 5
Views: 349

Re: Converting TAP to WAV files for Spectrum

is it possible that that particular program does not work on a +3 there are some incompatiblities.

regards Andy