Search found 48 matches

by PurpleGirl
15 Oct 2019, 00:35
Forum: Hardware and software hacking
Topic: Modified Gigatron Design Ideas
Replies: 57
Views: 26786

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...
by PurpleGirl
09 Oct 2019, 15:24
Forum: Hardware and software hacking
Topic: High resolution mode?
Replies: 38
Views: 15370

Re: High resolution mode?

Would capacitors help smooth over the transition? And would the final chip need to be faster or slower? There are faster TTL-compatible chips, but if the signal before that is not changing fast enough, might that make it worse?
by PurpleGirl
09 Oct 2019, 04:58
Forum: Hardware and software hacking
Topic: Modified Gigatron Design Ideas
Replies: 57
Views: 26786

Re: Modified Gigatron Design Ideas

I guess if I wanted to separate the video, I probably should to it incrementally and leave the BIOS alone until it works. The horizontal pulse is likely the easiest one to get rid of. A pulse generator, probably best derived from the existing clock can generate the syncs, though for starters, since ...
by PurpleGirl
07 Oct 2019, 12:59
Forum: Hardware and software hacking
Topic: Modified Gigatron Design Ideas
Replies: 57
Views: 26786

Re: Modified Gigatron Design Ideas

I hadn't thought about serializing it. If the address range is at a fixed location, chips could be arranged to be addressed by the pixel counter. So the pixel counter in the video could be used to strobe the memory. As for how to safely access the memory externally, two ideas come to mind. One is to...
by PurpleGirl
07 Oct 2019, 11:11
Forum: Hardware and software hacking
Topic: 10MHz, 12.5MHz and Beyond!
Replies: 24
Views: 7208

Re: 10MHz, 12.5MHz and Beyond!

Potato Semiconductors only has a few of the logic chips used. I mention them since their chips run around the GHz range. http://www.potatosemi.com/ It seems they only have the OR gates and a couple of different buffer chips that are used by the Gigatron. It seems that they have none that are used by...
by PurpleGirl
07 Oct 2019, 10:44
Forum: Hardware and software hacking
Topic: Modified Gigatron Design Ideas
Replies: 57
Views: 26786

Re: Modified Gigatron Design Ideas

Oh, so encoding is the opcode, I see. Where can I find such talks? So if that is just a line of pixels, then I could find a way to get them from memory and output them? And could I use an external clock, or would I have to derive the clock from the system clock to ensure compatibility? I am not sure...
by PurpleGirl
07 Oct 2019, 06:03
Forum: Hardware and software hacking
Topic: Modified Gigatron Design Ideas
Replies: 57
Views: 26786

Re: Modified Gigatron Design Ideas

Yes, as you can see, I'm more interested in using the Gigatron plans as a base for another project. I tend to be more after performance than nostalgia. So figuring out how to do the mods I mentioned and modify the ROM to remain operational. Maybe you can explain more how that code sends the data to ...
by PurpleGirl
06 Oct 2019, 13:07
Forum: Hardware and software hacking
Topic: Modified Gigatron Design Ideas
Replies: 57
Views: 26786

Modified Gigatron Design Ideas

I have not built a Gigatron yet. It seems very interesting. What I'd like to see is a way to get the video out of software and have dedicated circuitry for it. Now, generating sync pulses is the easiest. But I can't figure out where the pixels come from. If they were in memory, then some sort of mul...