Search found 486 matches

by at67
01 Jul 2022, 11:46
Forum: Hardware and software hacking
Topic: Musings on compatibility breaking changes.
Replies: 4
Views: 134

Re: Musings on compatibility breaking changes.

LD [A_Low],AC ADD [B_Low],AC ST [Result_Low] LD IN1,AC blt .carry LD [A_High],ac ADD [B_High],AC bra .done .carry: add 1,AC ADD [B_High],AC .done: ST [Result_High] A couple of issues with your theoretical code: 1) You add 1 to the high byte for both carry and non carry paths, because of the branch ...
by at67
30 Jun 2022, 09:32
Forum: Hardware and software hacking
Topic: Gigatron Clone Ideas
Replies: 46
Views: 1679

Re: Gigatron Clone Ideas

bmwtcu wrote: 30 Jun 2022, 01:29 Schweet! Fixed the FPGA code by adding if(cu_pl_n) to the PC increment. Tested on ROMv3/v4/vX0. (Love those DIP switches!)
Good job!

P.S. I have been switching between three ROM's with the press of one button since 2018 :P
viewtopic.php?p=172#p172
by at67
29 Jun 2022, 17:53
Forum: Hardware and software hacking
Topic: Gigatron Clone Ideas
Replies: 46
Views: 1679

Re: Gigatron Clone Ideas

OK, I've had a better look at this, single stepping native code on ROMv4 in both SW emulation and on real Gigatron hardware and I can't see an issue at all with the original code or the original circuit timing. If I had to guess, there seems to be a race condition between the JMP instruction and inc...
by at67
28 Jun 2022, 12:33
Forum: Hardware and software hacking
Topic: Would emulating vCPU on a Propeller 2 be feasible?
Replies: 9
Views: 161

Re: Would emulating vCPU on a Propeller 2 be feasible?

If you want to just emulate the Von Neumann vCPU 16bit instruction set, that's pretty trivial on any decent modern architecture. If you want 100% .gt1 compatibility then you have to emulate all the Sys calls, zero page registers, audio registers, VBlank registers, scanline VTable, etc, etc. No so tr...
by at67
28 Jun 2022, 12:26
Forum: Hardware and software hacking
Topic: Gigatron Clone Ideas
Replies: 46
Views: 1679

Re: Gigatron Clone Ideas

Well done on getting it to boot ROMv1!
by at67
26 Jun 2022, 01:19
Forum: Support
Topic: Not sure what to do with pluggy reloaded
Replies: 8
Views: 279

Re: Not sure what to do with pluggy reloaded

These errors mean that sdChipSelectPin has not been defined or that it is set to -1. You need to set it to whatever pin on your Arduino is used to access the SDCard. e.g. for the ARDUINO_AVR_PROMICRO, (which is what Pluggy Reloaded uses), you should have something like this: #if defined(ARDUINO_AVR_...
by at67
22 Jun 2022, 10:03
Forum: Hardware and software hacking
Topic: Gigatron Clone Ideas
Replies: 46
Views: 1679

Re: Gigatron Clone Ideas

All six cases are used to return from vCPU code into the current video scanline handler, unfortunately you can't just replace: ld(hi('vBlankStart'),Y) jmp(Y,[vReturn]) ld(0) with: ld(hi('vBlankStart'),Y) ld([vReturn]) jmp(Y,AC) ld(0) As this will break timing of the display by 1 cycle; I'm not sayin...
by at67
27 May 2022, 15:46
Forum: Hardware and software hacking
Topic: Gigatron Clone Ideas
Replies: 46
Views: 1679

Re: Gigatron Clone Ideas

Looks fantastic, well done!
by at67
22 May 2022, 22:00
Forum: Hardware and software hacking
Topic: Memory detection
Replies: 12
Views: 543

Re: Memory detection

"gtasm bricks.vasm" generates bricks.gt1 file, but I have to change the first byte of generated bricks.gt1 from 0x01 to 0x00 to make a correct bricks.gt1, once done this bricks.gt1 runs well (strange) bricks.vasm has nothing to do with GLCC, it was written in a stand alone assembler known...