Search found 8 matches

by Lerc
24 Aug 2020, 21:09
Forum: Hardware and software hacking
Topic: microtron
Replies: 42
Views: 6737

Re: microtron

Despite not reducing logic gates, replacing the four X and PC incrementers with two 867 might reduce even further chip count also in "standard gigatron" (as a "type 1" change with full hw/sw compatibility). And without external carry ripple might be even marginally faster. The 590 instead seems to ...
by Lerc
16 Aug 2020, 21:05
Forum: Hardware and software hacking
Topic: microtron
Replies: 42
Views: 6737

Re: microtron

I've found a very interesting article on generating full vga signal via a single counter and few other components: https://hackaday.io/project/9782-nes-zapper-video-synth-theremin/log/32271-vga-sync-generation I must say, that seems like a little bit of genius. I especially like the first comment s...
by Lerc
27 Jul 2020, 21:07
Forum: Hardware and software hacking
Topic: microtron
Replies: 42
Views: 6737

Re: microtron

I'm not sure I got this point (what exactly to OR and for what reason), but let me say that I would probably prefer suggestions to remove chips than to add if possible! :D The OR combining would be for using two 8 bit inputs instead of nibbles on Load W. It would let you do operations where bits in...
by Lerc
26 Jul 2020, 20:10
Forum: Hardware and software hacking
Topic: microtron
Replies: 42
Views: 6737

Re: microtron

OK I've been staring at the diagram and thinking a lot and I understand it a lot more. That makes me think that I need to think a lot more. Using 32 bit instructions with directly embedded control lines throws the possibilities of instructions completely up in the air. Not only is much more possible...
by Lerc
23 Jul 2020, 21:10
Forum: Hardware and software hacking
Topic: microtron
Replies: 42
Views: 6737

Re: microtron

It's interesting to compare with modifications I was imagining, While I pretty much want to add a bunch of chips, the minimization effort of the Gigatron has built a base where you can branch out from. A even more minimal approach could potentially give a lower base to work from. I only have this ba...
by Lerc
23 Jul 2020, 03:28
Forum: Hardware and software hacking
Topic: Help Sourcing Part
Replies: 4
Views: 836

Re: Help Sourcing Part

The VGA pixel clock is officially 25.175MHz so using 6.25 * 4 is already a little out. The ideal would presumably be 6.29375MHz. A 6.3MHz clock would be closer. 6.33333MHz is about the same amount out the other way. They might exist as crystals if people are doing things in thirds a bit, I haven't l...
by Lerc
18 Jul 2020, 23:27
Forum: Hardware and software hacking
Topic: High resolution mode?
Replies: 38
Views: 19506

Re: High resolution mode?

So I mentioned a while back that I wrote a program to try some 4 bit digital to 16 colour RGB that was nicer than CGA's RGBI. I rewrote the program and after a lot of fiddling I came up with a resister arrangement that wasn't too complex and produced a set of colours that I thought were good. https:...
by Lerc
21 May 2020, 21:48
Forum: Hardware and software hacking
Topic: High resolution mode?
Replies: 38
Views: 19506

Re: High resolution mode?

Hi, I saw the Apple I story and fell down the rabbit hole. So I'm fairly new to all this, but I'm halfway through laying out my own variant in a simulator. I'm posting in this thread because I was kept awake by ideas for the video out. I'm a complete novice so I half expect this to be gibberish, but...