Search found 1060 matches

by groepaz
Thu Oct 19, 2023 9:26 am
Forum: Emulation and Cross Development
Topic: VICE key-rollover inconsistencies
Replies: 3
Views: 2063

Re: VICE key-rollover inconsistencies

I have implemented (partial) emulation of the Keyboard matrix quirks some years ago - indeed only for C64 (and C128 i believe). Even for those, it doesn't really work right in all cases (but good enough for 3 keys i think). It's quite a surprisingly complex problem unfortunately :) So no, you are no...
by groepaz
Wed Oct 11, 2023 4:51 am
Forum: Hardware and Tech
Topic: Making a cheap Power supply.
Replies: 5
Views: 2211

Re: Making a cheap Power supply.

It'll work - mostly - if you don't connect anything at all to the 9VAC pins. That voltage is used on the user port for things like RS232 and some modems, and also for the datasette motor.
VIC20, yes
by groepaz
Fri Oct 06, 2023 1:37 pm
Forum: Emulation and Cross Development
Topic: Stack Watching in VICE
Replies: 21
Views: 4185

Re: Stack Watching in VICE

rhialto made a quick patch

http://www.falu.nl/~rhialto/watchpoints1.diff.txt

eg

break load 0 $ffff if @cpu:(pc) < $80
by groepaz
Fri Oct 06, 2023 10:27 am
Forum: Emulation and Cross Development
Topic: Stack Watching in VICE
Replies: 21
Views: 4185

Re: Stack Watching in VICE

BTW, i am offering a crate of beer to whoever implements a "dereference" operator for the conditions (so you can use the content of the memory whatever expression points to) - that would be super useful indeed :)
by groepaz
Fri Oct 06, 2023 8:38 am
Forum: Emulation and Cross Development
Topic: Stack Watching in VICE
Replies: 21
Views: 4185

Re: Stack Watching in VICE

Can the value of the memory at PC be used?
Unfortunately not
by groepaz
Fri Oct 06, 2023 7:28 am
Forum: Emulation and Cross Development
Topic: Stack Watching in VICE
Replies: 21
Views: 4185

Re: Stack Watching in VICE

I don't think this can be done directly (please correct me if i am missing something) - you can only compare registers and memory locations, there is no way to tell "was pulled from stack". Perhaps you can do something like ($100+SP)=$55 && A=$55 (which is obviously not really what...
by groepaz
Mon Oct 02, 2023 5:21 am
Forum: Programming
Topic: C=Hacking Issue 8 - fast plot routine with 20 cycles
Replies: 7
Views: 2254

Re: C=Hacking Issue 8 - fast plot routine with 20 cycles

Next step would be unrolling the loop for each needed slope... perhaps not on VIC20 though :)
by groepaz
Fri Sep 22, 2023 3:27 pm
Forum: Games
Topic: Crazy Cavey
Replies: 11
Views: 2795

Re: Crazy Cavey

Raster tricks are actually easier than on VICII - since there are no "bad lines". Very straight forward :)
by groepaz
Fri Sep 22, 2023 2:35 pm
Forum: Hardware and Tech
Topic: Making a cheap Power supply.
Replies: 5
Views: 2211

Re: Making a cheap Power supply.

I don't think you'll fry something - but it will not work :)
by groepaz
Wed Sep 13, 2023 12:08 pm
Forum: Hardware and Tech
Topic: I/O0 and illegal opcodes
Replies: 9
Views: 2631

Re: I/O0 and illegal opcodes

Also I know the C64-fastloader Spindle uses illegals to do GCR-decoding on the fly which was deemed impossible before.
All the modern loaders do :)
by groepaz
Wed Sep 13, 2023 9:53 am
Forum: Hardware and Tech
Topic: I/O0 and illegal opcodes
Replies: 9
Views: 2631

Re: I/O0 and illegal opcodes

but there does exist software that uses the so-called "illegal opcodes". To add to this: not seldom in old games there are undocumented opcodes executed not because the coder used them intentionally, but because they are a result of accidental memory corruption during development. (This i...
by groepaz
Sun Sep 10, 2023 11:22 am
Forum: Other Systems
Topic: New Release: PETSTRIP for PET/CBM 3032 and 4032
Replies: 5
Views: 2162

Re: New Release: PETSTRIP for PET/CBM 3032 and 4032

This is really very cool. Imagine showing this to ppl back in 1980 :=)
by groepaz
Sun Jul 02, 2023 5:22 pm
Forum: Programming
Topic: Need help converting multicolor font from atari to commodore.
Replies: 1
Views: 1081

Re: Need help converting multicolor font from atari to commodore.

As said on Lemon - can't you simply use it as is? The binary format should be the same
by groepaz
Sun Jul 02, 2023 5:37 am
Forum: Other Systems
Topic: Help modifying C64 PAL code for NTSC machine
Replies: 5
Views: 2300

Re: Help modifying C64 PAL code for NTSC machine

It uses PB7 indeed, and that's L - correct

The problem might indeed be the video source - if the video was deinterlaced, ie is now 25fps, then it will probably not work
by groepaz
Sat Jul 01, 2023 7:23 am
Forum: Other Systems
Topic: Help modifying C64 PAL code for NTSC machine
Replies: 5
Views: 2300

Re: Help modifying C64 PAL code for NTSC machine

Generally on NTSC everything needs to be 20% percent faster (50Hz PAL vs 60Hz NTSC). So, when you you look at the code, there is one delay loop at $c044 which is called with different values in X at various places. So the first/easy attempt is to make this delay loop 20% faster (which then means all...