Michael J. Mahon wrote:
I've always had a fondness for 6522-based cards (like the Mockingboard)
since they have two counter/timers and two bi-directional parallel
ports (plus handshake lines), and can generate interrupts.
It's a very versatile card, and you can terminate the data cables (D1
and D2) in any way that is useful for your purposes.
Most 6522-based cards did not contain EPROMs (unless they were intended
to interface with printers), but software is usually written for each
specific purpose to which they are applied.
A little tracing of address wires will usually confirm that the chip's
16 registers are mapped directly into the /DEVSEL space ($C0sx).
I believe you are correct as to the board's purpose. But, why are
there two cables, each with 16 wires? There is also an EPROM (or, what
I naively call an EPROM: has a little window on it presumably to erase
it?)