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Re: Gigatron Clone Ideas

Posted: 10 May 2022, 17:36
by alastair
Initial chip placement. The connectors and associated components haven't been added yet; they would go along the bottom edge. The gap is for the Pluggy Reloaded components. I left the option to use the existing Pierce Oscillator/6.25MHz crystal or you can use the can oscillator and divider (bottom left chip). The bottom right chip is for hi-res mode. I made room to install a 40-pin ZIF socket for the ROM. No video repeater though... I am thinking about adding headers to make it easy to install daughter cards for additional features/options. The board is designed to fit in a ZN-40 case. There's a power switch, but I still need to figure out where to put the blinken lights.
novatron.jpg
novatron.jpg (260.91 KiB) Viewed 168 times

Re: Gigatron Clone Ideas

Posted: 14 May 2022, 03:45
by alastair
Mostly routed. I was going to test the new design on a breadboard, but the only real change are the PALs. These can be reprogrammed so most of the debugging will be in firmware... assuming I didn't screw up the schematic. The ATtiny85 is on the board for the basic Pluggy, so it can be built to match the v2 Gigatron. I still plan to add the Pro Micro/SD Card on board for the Pluggy Reloaded option. 6-bit audio is standard with a single bi-color LED for a blinken light. Other options on board include the oscillator/divider for overclocking and 8 color hi-res mode with selector switch.
novatron.jpg
novatron.jpg (263.5 KiB) Viewed 116 times

Re: Gigatron Clone Ideas

Posted: 17 May 2022, 15:27
by bjchapm
This looks great. Very cool development.

Re: Gigatron Clone Ideas

Posted: 17 May 2022, 16:03
by bmwtcu
alastair wrote: 14 May 2022, 03:45 ...the only real change are the PALs. These can be reprogrammed...
Very cool! I've only used GALs (which are reprogrammable) before, but I thought that PALs were OTP?

Re: Gigatron Clone Ideas

Posted: 17 May 2022, 17:12
by alastair
bmwtcu wrote: 17 May 2022, 16:03 I've only used GALs (which are reprogrammable) before, but I thought that PALs were OTP?
I usually use GALs, specifically the ATF16V8B for development. I try and stick within the original PAL specs so you could build it with the vintage parts. I do have some NOS PALs for another project, but I still need to recompile the JEDEC file so I can program them.

Re: Gigatron Clone Ideas

Posted: 17 May 2022, 20:34
by klf
PAL16V8 is metal fuse PROM. GAL16V8 is EEPROM, HAL16V8 is mask ROM. 16V8 architecture is always the same.