Thanks for the input. My problem with the
"Unobtainiums" is that not
only
were they MOSTEK chips with their
own pinout,
No, they aren't! They were made by MOS Technology, which was
NOT the same company as Mostek.
Mostek made SRAMs (but not the 6550), DRAMs, masked ROMs, and second-sourced
the Z80, F8, and 68000 families. The also made a lot of telecom chips, like
DTMF encoders. They were acquired by Thomson, and are now part of ST Micro.
MOS Technology made calculator chips, 65xx microprocessors and peripheral
chips, masked ROMs, and static RAMs. They were acquired by Commodore,
and when Commodore folded they basically ceased to exist. (Someone must
own the rights to the MOS Technology stuff, but it's not obvious who.)