Gigatron Hackers

I was leaning towards ... this Scratch that. There's only 6 bits available because I still need the H & V sync bits. That would be 3 bits each per pixel and the basic 1 bit RGB colors. These can be maxed out (>1V) to fully saturate the colors and get the "classic" 8 color palette.

I was leaning towards a 74HC244 ganged to this with a 3PDT switch to select between the two resistor DACs. I could also look at using some 74HC670 register files as a RAMDAC and have a way to load the palette colors during blanking. Anther option with a RAMDAC is doubling up again, so 4 pixels per c...

Video Repeater : https://forum.gigatron.io/viewtopic.php?t=303 I was debating the video repeater but might not go that far. 25MHz oscillator with jumper selectable /1,/2 and /4 clock options using 74LS74. This is probably how I will go. I need a symmetrical clock from a flip-flop with a Q and ~Q ou...

I've been thinking about doing a Gigatron clone for some time and finally sketched out an initial plan. This would be binary compatible with the existing code base, but with some of the newer ideas integrated on a new PCB. These include: * Pluggy Reloaded * 6-bit Audio * High Resolution as an option...

I assume this would be the latest font - https://github.com/kervinck/gigatron-rom/blob/master/Core/font_v4.py I'm not too familiar with the build process, but you can checkout the repo and either modify this file or create a new version and pull that in to the build. There should be info in this for...

The passive components of the Pierce oscillator circuit are designed for CMOS. E.g. the feedback resistor is 1M ohm. For a 74LS04 you will need to drop this significantly to around 1k ohm. This is an example I built using F-series TTL chips. You may need to play with the values of the resistors and ...

Maybe someone else can give it a go? I can explain the delta: You would replace R9 with the 8-bit version - https://www.mouser.com/ProductDetail/bourns/4610x-r2r-103lf/?qs=aoibn3z0pk31UFm1GxQJlw%3D%3D Pins 1-5 of the new R9 would remain unchanged, pin 10 would go to ground. The rest of the pins on ...

What's caused the project to stall is actually not getting bored of writing native code - in fact I'm trying to go back to writing native code to re-kindle the enjoyment. Glad to hear it's still ongoing :D I've been working on a similar project to the Gigatron and spent the last year coding in my n...

Add more memory addressing modes -- Most would love to have more addressing modes to simplify coding. This got me thinking. Who else has written (native) code for the Gigatron? Obviously Marcel and there is one other project I'm aware of - https://hackaday.io/project/168293-gigatron-forth Working d...

I started studying the RCA 1802 . I am pretty sure the Gigatron can outrun it, even in vCPU mode. It was a somewhat odd CPU. I worked on a v1802 implementation for a similar project, but switched to a v8080 on Marcel's recommendation :lol: The 1802 is a good fit for a virtual CPU since the overhead...