Search found 1556 matches

by Andy Rea
Sun Oct 13, 2019 4:09 pm
Forum: Welcome Area
Topic: Hello from Nottingham, UK.
Replies: 21
Views: 1289

Re: Hello from Nottingham, UK.

Welcome to the Forum, Lots of love for the humble machine. you can really do alot with it.

any questions just ask away.

Regard Andy
by Andy Rea
Mon Oct 07, 2019 1:37 pm
Forum: Hardware
Topic: Mystery 330 ohm resistor connected to X1
Replies: 4
Views: 427

Re: Mystery 330 ohm resistor connected to X1

I've seen similar on zx81 isue 3 boards with red solder mask but in my case they were 1K resistors

Andy
by Andy Rea
Tue Oct 01, 2019 2:21 pm
Forum: Hardware
Topic: ZXPand vs ZXPand+ ?
Replies: 2
Views: 519

Re: ZXPand vs ZXPand+ ?

put the sd in after powering on and see if it is recognised do a CAT
by Andy Rea
Mon Sep 30, 2019 9:55 pm
Forum: Development
Topic: DOOM on ZX81?!
Replies: 3
Views: 693

Re: DOOM on ZX81?!

awesome that preview looks really smooth, will download and try on real hardware... BOBS played with ray traced texture mapping in lo-res a long time ago... https://www.sinclairzxworld.com/viewtopic.php?f=4&t=548&p=4951&hilit=3d+rendering#p4951 the facebook video link https://www.facebook.com/bobs.s...
by Andy Rea
Mon Sep 30, 2019 9:50 pm
Forum: Hardware
Topic: Re-enable ZXpand after CONFIG "X"
Replies: 6
Views: 750

Re: Re-enable ZXpand after CONFIG "X"

Nice Trick, Thanks for sharing...

Andy
by Andy Rea
Fri Sep 27, 2019 11:45 am
Forum: Development
Topic: Problem with TASM 3.2
Replies: 10
Views: 927

Re: Problem with TASM 3.2

yes JR 4 bits lol nope..

JR and index offsets both 8bit SIGNED
by Andy Rea
Fri Sep 27, 2019 11:29 am
Forum: Development
Topic: Problem with TASM 3.2
Replies: 10
Views: 927

Re: Problem with TASM 3.2

quoted instead of edit :( sorry
by Andy Rea
Fri Sep 27, 2019 11:28 am
Forum: Development
Topic: Problem with TASM 3.2
Replies: 10
Views: 927

Re: Problem with TASM 3.2

haha your right the IX and IY registers can't be negative but for example say they are holding the value $0000 and you add a negative offset it will roll round to $ffff for -1 $fffe for -2 $fffd fro -3 and so on... btw LD IY,-20000 ; is perfectly valid and results in the following bytes DD 21 E0 B1 ...
by Andy Rea
Fri Sep 27, 2019 9:55 am
Forum: Development
Topic: Problem with TASM 3.2
Replies: 10
Views: 927

Re: Problem with TASM 3.2

when using the index registers the offset byte is signed so -128 to +127 is the maximum range allowed.

same as relative jumps.

tasm allows you to enter negative numbers.

regards Andy
by Andy Rea
Sat Sep 21, 2019 10:36 pm
Forum: Hardware
Topic: PRYNT, POKU, bad ROM or ULA in TS1000?
Replies: 15
Views: 1562

Re: PRYNT, POKU, bad ROM or ULA in TS1000?

IR=$1E00 R= %000* 0000 (*) Where the bit B4 is set to 1. 000* 0000 "(" 000* 0001 ")" 000* 0010 ">" 000* 0011 "<" 000* 0100 "=" 000* 0101 "+" 000* 0110 "-" 000* 0111 "*" 000* 1000 "/" 000* 1001 ";" 000* 1010 "," 000* 1011 "." 000* 1100 "0" 000* 1101 "1" 000* 1110 "2" 0001 1111 "3" 0001 0000 "(" 0001...