Gigatron Hackers

wbushby wrote: ↑29 Jul 2021, 09:56 I don't have the SD card ROM installed. Where does that go ?
Does that replace ROMv5a.rom ?

Yes it does, follow the link in bmwtcu's post.

I decided to give it another try a few months ago. I studied the old compiler and stole the good ideas, such as having a combined assembler-linker written in python. I rewrote a very different code generator (with some novel ideas in fact) and I solved the register spilling problems. Then I started...

I just ran some experimented with a batch of indirect-indexed instructions. The encoding is as follows: PREFIX VAR OPCODE OFFSET I'm going to use this format, (as you suggested), for PREFX3 to save a few cycles. Overall I believe this is a good idea. The implementation might have to be refined. In ...

Variable space. Is there a backwards compatible place that we could put this information? I kinda wish Marcel had allocated some of page 0 as "for future use". I guess this is with future ROM's in mind, if so then you could just use the 0x3X space; Marcel reserved 0x30 to 0x33 for VBlank ...

It can't be shared between virtual machines - code that is part of a vCPU or v6502 instruction is destined always to return to its dispatch loop, and SYS functions are all linked to vCPU for the same reason. I'd like to be able to expose SYS functions in my Forth, and it's possible, but it always i...

Yes, I think to do both bytes and the transfer in 30 is not possible. If you could do it in two-phases it should work (but how would you dispatch to different code the on the second and subsequent calls?). My implementation of Arithmetic shift-right is 45 excluding the cost of dispatch and I though...

I've implemented a LSRB, (non PREFX instruction), in ROMvX0, so applying this technique, (as a PREFX restart-able instruction), to allow right byte shifts from 1 to 7 should be doable. But I was never able to get a LSRW implemented in under 30 cycles. In fact I wasn't even close, I think my best was...

Ideas for prefix2. So, before even thinking of supporting long and float arithmetic with SYS calls, it would be desirable to have MOVL v1,v2 (moving 4 bytes) and MOVF v1,v2 (moving 5 bytes), and maybe even LOKEA/LEEKA and fp equivalents (FOKEA might not be a good name.) Doing this might involve wri...

I've added your GT1 files to the GT1 repository at: https://www.dropbox.com/sh/4bbys2afg9y6 ... tlBza?dl=0

I've updated the GT1 repository with additions from hans61, delpozzo and myself. As always if anyone has GT1 examples/apps/games/etc they would like stored in a central easy to access location, then just send me a PM or reply to this thread; also if anyone wants their GT1 files removed for whatever ...