Search found 47 matches

by PurpleGirl
02 Nov 2019, 03:29
Forum: Escape Meta Alt Control Shift
Topic: On the shoulders of Giants
Replies: 6
Views: 1379

Re: On the shoulders of Giants

Since I see you now have ports planned, I'd like to make a suggestion. I think you should use the 8 bits at the end of the instruction to specify a port address. That way, you could support up to 256 ports. And whoever makes peripherals could use simple address decoder logic to see if it is the devi...
by PurpleGirl
02 Nov 2019, 03:16
Forum: Hardware and software hacking
Topic: dual core Gigatron CPU
Replies: 55
Views: 2479

Re: Modified Gigatron Design Ideas

What would be a decent FIFO to use? I never really thought of FIFOs and shift registers. So any information on those would be a good start. Now I am not sure how such a card can tell the Gigatron that it needs data in its FIFO registers or how software could get it. There is currently no way to sign...
by PurpleGirl
31 Oct 2019, 07:33
Forum: Hardware and software hacking
Topic: dual core Gigatron CPU
Replies: 55
Views: 2479

Re: Modified Gigatron Design Ideas

A compromise comes to mind. The existing clock (or a clock divider if going for 12.5 Mhz) could be used to drive a pixel counter. The idea of intercepting a NOP instruction to create a video reset could be used on power-up to reset the pixel counter and any other time the pixels being sent might not...
by PurpleGirl
21 Oct 2019, 00:13
Forum: Hardware and software hacking
Topic: Pluggy Reloaded
Replies: 59
Views: 2776

Re: Pluggy Reloaded

From what I see, VCC comes from the Gigatron. The USB's VCC comes from the controller chip, and that chip gets it from the Gigatron. I am wondering if the VCC to the chip and the VCC to the USB port are not wired the opposite way on the controller. It seems VCC on the chip should feed the chip and t...
by PurpleGirl
21 Oct 2019, 00:01
Forum: Escape Meta Alt Control Shift
Topic: On the shoulders of Giants
Replies: 6
Views: 1379

Re: On the shoulders of Giants

I've been thinking more about a Suite-16 being used as a Gigatron. Obviously, you'd need at least 1 IN port and 2 OUT ports, and ROM. If you had a 16-bit X-Out, I could think of various ways to use those bits. For instance, if you wanted blinkenlights, that leaves 12 bits, and you could have 2 6-bit...
by PurpleGirl
20 Oct 2019, 20:50
Forum: Escape Meta Alt Control Shift
Topic: On the shoulders of Giants
Replies: 6
Views: 1379

Re: On the shoulders of Giants

I notice that you sort of planned to address 24-bits of memory by combining the payload with a register, I also read that your jumps and calls are 16-bits. I got to thinking that you could use the payload byte along with the next 2 bytes and do 24-bit jumps and calls. But then I read that you might ...
by PurpleGirl
19 Oct 2019, 03:06
Forum: Hardware and software hacking
Topic: dual ported SRAM for co-processing
Replies: 5
Views: 689

Re: dual ported SRAM for co-processing

An idea I had was to put 32k dual-ported RAM on 2 Gigatrons and do crisscross addressing. Instead of using the high bit to address larger memory, it is used to switch a multiplexer and address the memory on the other machine. So the low 32k is the local Gigatron, and the high 32k is the other Gigatr...
by PurpleGirl
18 Oct 2019, 20:49
Forum: Hardware and software hacking
Topic: dual core Gigatron CPU
Replies: 55
Views: 2479

Re: Modified Gigatron Design Ideas

I already mentioned how I'd do a video card reset command. One of the NOPs can be piggybacked. They already do nothing. I never mentioned changing any, just adding functionality to one. So all it takes is adding minor decoder logic for the desired instruction. I mentioned how to NOR the pins expecte...
by PurpleGirl
17 Oct 2019, 22:08
Forum: Hardware and software hacking
Topic: dual core Gigatron CPU
Replies: 55
Views: 2479

Re: Modified Gigatron Design Ideas

I was talking about modifying a Gigatron. Since there are 12 NOPs, I could intercept one for use for the "video card" for it. Thus once I discover the opcode I want to intercept, I can use logic to see if the appropriate low bits are low and the high ones are high, make a single signal out of it, an...
by PurpleGirl
15 Oct 2019, 00:35
Forum: Hardware and software hacking
Topic: dual core Gigatron CPU
Replies: 55
Views: 2479

Re: Modified Gigatron Design Ideas

Another idea came to mind. Why not piggyback an unused NOP instruction as a function to reset dedicated video HW? That way, HW can manage the syncs, but if things get out of sync or software cannot be trusted, then issuing an alternative NOP would reset the pixel counter. As for intercepting the ins...