Well, this didn't all go according to plan...
It turns out that the Mojo IO Shield is unsuitable for a front panel because
it utilizes every sing available IO pin, leaving none for peripherals. So,
I've had to make my own front panel. (
http://coldwarcomputing.com/maximilian.jpg)
I've decided to implement two independent PDP-8 cores on the same FPGA, each with its own mass storage, core memory, and two UARTs.
I've also decided to use FRAM for the system memory, to mimic the
non-volatile core memory of the original machines. Theoretically, it should
be possible to unplug a running machine, plug it back in, and have it pick up right where it left off. This will slow it down significantly, but it should still be faster than the original hardware.
The end goal of this project is to make a simple(?) PDP-8-based, FidoNet-capable, single-user-at-a-time BBS. That might be a bit more
difficult than it sounds, because I'm not even sure Zip/Unzip were
implemented on these machines and I'll probably have to do that from scratch. But that's why I decided on two cores: one to handle BBS stuff, and one to handle FidoNet stuff.
Jeff.
"For every complex problem there is an answer that is clear, simple, and wrong." -- H. L. Mencken, who indeed was a racist thereby proving himself right.
--- Mystic BBS v1.12 A46 2020/08/26 (Raspberry Pi/32)
* Origin: Cold War Computing BBS (21:1/180)
