Gigatron Hackers

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 ...

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
https://forum.gigatron.io/viewtopic.php?p=172#p172

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...

https://forum.gigatron.io/viewtopic.php?t=82

https://www.jcwolfram.de/projekte/gtmicro_en/main.php

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...

Well done on getting it to boot ROMv1!

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...

Looks fantastic, well done!

"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...

Yes and Yes.

P.S. The ATtiny85 doesn't support the PC COM/USB interface, it only supports the controller and PS2 keyboard. You need to use one of the beefier Arduino's to get access to a PC.