Gigatron Hackers

You could implement a monochrome display by taking the four of the six bits used for the color and putting them in a shift register. The remaining two bits could be used to select one of four colors. The shift register output would select this color if the bit was one, else it would be blank/black. ...

The video line is managed by the code in page 2 of the ROM. The row is tracked by zero page parameter videoY and frameCount is used as a simple system clock. There isn't a column value since the column is just 160 ora([Y,Xpp],OUT) instructions in a row with no time to do anything else.

petersieg wrote: ↑11 Jul 2023, 13:24 Some pictures and more information would be nice.

I'll start a new thread and post some pictures when I've wrapped up some things. It's basically the "Novatron", but I changed the name (due to a conflict with another project) and switched to a full-size SD card.

I have a clone of the Gigatron in a slightly smaller form factor. I use some simple 16V8 GALs to replace the diode ROM and integrate the 128k/SD card expansion on board. I'm putting a kit together but also looking at producing an assembled version. The assembled version uses SMDs for the passive com...

The SPI1 connector matches the standard SD card pinout so I plugged one in just now and tested it. I can read both SD cards no problem. I have one unused pin on the PAL (19) and could connect that to BUS2 and BUS3 using two diodes. I should be able to fit those on the board in a future revision. Tha...

Thanks for figuring this out @lb3361 I was going to take a closer look at the code but got tied up with another project. I tried the latest ROM and everything is working correctly now! I don't have enough pins on the 16V8 PAL to connect the four BUS lines. I'm only using BUS0 but also have BUS1 conn...

Thanks for the new ROM Leo. The original card is showing three lines after the boot message. The first is all white pixels and the next two are all red. I picked up a new SD card and get three all white lines. This was the case with the card in its original FAT32 formatted state and after loaded the...

There was a bit of a trick needed to dd the image from MacOS (/dev/rdisk2). I can now copy the image and mount it correctly. The new ROM version fixes the "Vol.ID 0101" error, but I'm now getting "FAT32 FAILED". I get this error with both a clean FAT32 formatted drive and the sd....

I'm still seeing the same issue. I unzipped the file to the correct 64M size and then transferred it using dd. Once complete the card wasn't recognizable on my Mac or Windows machines, but showed the same error on the Novatron. I'll see if I can get some different cards and try those.

Thanks @lb3361. I don't have a lot of SD Cards and this was the only one I could find at short notice. Picture attached of the card and format on Mac. I had to zip the sd.bin file so it would attach (it just contains system.gt1 right now): sd-card.jpg Screen Shot 2022-09-08 at 8.38.26 AM.png sd.zip