Search found 311 matches

by at67
06 May 2021, 17:29
Forum: Hardware and software hacking
Topic: New vCPU instructions 2.0
Replies: 76
Views: 4097

Re: New vCPU instructions 2.0

Here is what the implementation of PREFX3, it's dispatch page and some corresponding instructions look like now, you'll note the following: Reset to the default vCPU page is now handled in dispatch. vPC fix up is handled in PREFX3. Parsing of the 2nd instruction operand, (PREFX3 instructions always ...
by at67
04 May 2021, 18:34
Forum: Hardware and software hacking
Topic: New vCPU instructions 2.0
Replies: 76
Views: 4097

Re: New vCPU instructions 2.0

I see you've moved code some code to page 0. If I ever complete and merge my Forth, I need a short routine in page 0 (currently 5 instructions). Could you try to leave at least that much space for my purposes? The location isn't important. I used a 3 slot launchpad to move SYS_Reset_88's implementa...
by at67
04 May 2021, 18:06
Forum: Hardware and software hacking
Topic: New vCPU instructions 2.0
Replies: 76
Views: 4097

Re: New vCPU instructions 2.0

I didn't just mean it for prefix instructions. I just observe that half of the page3 instructions waste three cycles adjusting vPC. For these instructions, vPC is adjusted twice: once in the instruction body (+/-1) and once in the dispatch code (+2). Three cycles, that's 10% of maxTick, an obvious ...
by at67
04 May 2021, 17:36
Forum: Hardware and software hacking
Topic: Sprites
Replies: 6
Views: 629

Re: Sprites

denjhang wrote: 04 May 2021, 16:21 How should I compile ROMvX0, is there any one that has been compiled?
I haven't released it yet unfortunately, I should have by now, but work has taken up 90% of my time...I'll do my best to get it dropped soon, but no promises.
by at67
03 May 2021, 11:27
Forum: Hardware and software hacking
Topic: New vCPU instructions 2.0
Replies: 76
Views: 4097

Re: New vCPU instructions 2.0

Because nearly all old vcpu instructions were two bytes long, it made sense to lose 3 cycles adjusting vPC on the occasional one- or three-bytes long ones. But this is no longer the case with all your new instructions. So what about having three versions of REENTER for one-, two- and three- bytes i...
by at67
03 May 2021, 11:22
Forum: Hardware and software hacking
Topic: 6Bit audio:
Replies: 9
Views: 864

Re: 6Bit audio:

Thank you for your hint, I prefer 8-bit or even higher-quality audio to 6-bit audio. Regarding the hardware transformation of 8-bit audio, can you show me the schematic diagram? I am not very skilled in the circuit, but I would like to try it. I'm sorry, I don't have the time to design a circuit an...
by at67
02 May 2021, 13:01
Forum: Hardware and software hacking
Topic: New vCPU instructions 2.0
Replies: 76
Views: 4097

Re: New vCPU instructions 2.0

Sorry. We misunderstood each other. The nop idea was precisely a way to avoid the cycle count issue. Basically, make 0x35 a standalone nop instruction that just decrement vPC and returns to REENTER. Then 0x3f, 0x72, etc become opcodes for standalone short branches with their own cycle count. Then t...
by at67
02 May 2021, 07:30
Forum: Hardware and software hacking
Topic: 6Bit audio:
Replies: 9
Views: 864

Re: 6Bit audio:

I want to know how to implement 6-bit audio, and what changes need to be made on the hardware? , I am very interested in it. Because I use gigatron as a retro music player, and I will write some music for gigatron. You need to modify the ROM and obviously you need an expansion circuit to breakout t...
by at67
02 May 2021, 00:02
Forum: Hardware and software hacking
Topic: New vCPU instructions 2.0
Replies: 76
Views: 4097

Re: New vCPU instructions 2.0

Why [$d5] and not [$34], for instance... [$D5] was the only available zero page slot in the BASIC compiler that I am doing all my testing in, I'll do some re-organising and probably use [$34], but I only need to save one byte unlike Marcel's LUP/RESYNC system that needs to save a word. Also using [...
by at67
01 May 2021, 21:54
Forum: Hardware and software hacking
Topic: New vCPU instructions 2.0
Replies: 76
Views: 4097

Re: New vCPU instructions 2.0

This may not be important, but an easy way to implement the two bytes Bcc is to make the current Bcc opcode a NOP. Then the next instruction is a short Bcc. The only problem is that this makes the three bytes sequence a bit slower than the old Bcc. On the other hand, it would be easy to change gcl0...