Search found 875 matches

by siggi
Fri Dec 07, 2018 10:17 am
Forum: Hardware
Topic: Reversible 16K RAM
Replies: 4
Views: 170

Re: Reversible 16K RAM

McKlaud wrote:
Thu Dec 06, 2018 11:33 pm
And don't forget about 10k resistor between pins 27 & 28.
.. which is not necessary for this use case ;)

Maybe it has been necessary for ram extensions, which had a battery (to write-protect the ram during power-off state) ...

Siggi
by siggi
Thu Dec 06, 2018 11:16 pm
Forum: Development
Topic: New to Machine code, help required
Replies: 16
Views: 271

Re: New to Machine code, help required

Also, if you press the CONT key, your first routine will print another screen of characters... Thats because the JR NZ tests the value of the A Register, you are decrementing BC. No, JR NZ tests the Z-flag, which is part of the F register. It could be set by a lot of instructions (like "DEC C" or "...
by siggi
Mon Nov 26, 2018 6:42 pm
Forum: Hardware
Topic: 3K Rampack issues
Replies: 16
Views: 551

Re: 3K Rampack issues

Maybe it does not solve the current problem, but usually each chip should have its own capacitor (around 10-100nF), connected across its power pins to stabilize its power supply. If those C are missing, the board may run (because the logic is OK), but not very stable (because the power supply of a ...
by siggi
Mon Nov 26, 2018 10:20 am
Forum: Hardware
Topic: 3K Rampack issues
Replies: 16
Views: 551

Re: 3K Rampack issues

Maybe it does not solve the current problem, but usually each chip should have its own capacitor (around 10-100nF), connected across its power pins to stabilize its power supply. If those C are missing, the board may run (because the logic is OK), but not very stable (because the power supply of a c...
by siggi
Fri Nov 23, 2018 12:54 pm
Forum: Welcome Area
Topic: Holidays!
Replies: 3
Views: 246

Re: Holidays!

(Mrs Moggy lets me have the good single malt to bring in the new year) For information only: I have done several compatibility tests of Whiskey and the ZX81: Failure: http://forum.tlienhard.com/phpBB3/download/file.php?id=6100 Success: http://forum.tlienhard.com/phpBB3/download/file.php?id=6103 htt...
by siggi
Fri Nov 23, 2018 11:19 am
Forum: Hardware
Topic: 3K Rampack issues
Replies: 16
Views: 551

Re: 3K Rampack issues

Hi Mike I next printed out the PCB layout files and meticulously did a point-by-point check of all connections, finding no shorts or dead spots. Did you check/measure on the PCB or on the contact inside the socket (maybe soldering is the problem)? Soldering all components again often solves such pro...
by siggi
Fri Nov 23, 2018 9:10 am
Forum: Software
Topic: 2k adventure
Replies: 25
Views: 868

Re: 2k adventure

I started my program on a "Sinclair Diet", but I don't think I'm going to make the 2K finish line without some major loss of functionality, Without losing functionality a lot of bytes can be lost ;) Replace if condition1 then PRINT string1 if condition2 then PRINT string2 by print string1 AND condt...
by siggi
Thu Nov 22, 2018 1:59 pm
Forum: Software
Topic: 2k adventure
Replies: 25
Views: 868

Re: 2k adventure

Anyone care to pare it down with more of that PI/PI magic? You could save a lot of bytes by replacing numeric constants to VAL: 1 -> VAL"1" and by using variable assignments for equal values; LET a=1 LET b=1 - > LET a=VAL"1" LET b=a See https://www.sinclairzxworld.com/viewtopic.php?f=5&t=85&start=2...
by siggi
Mon Nov 12, 2018 9:52 am
Forum: ZX BASIC
Topic: SPeccy ON the ZeddY
Replies: 100
Views: 20611

Re: SPeccy ON the ZeddY

Yes, it is solved :D
Thanks
Siggi