[__d]

The decision to use this chip (vs the WD) in the BBC Micro made me wonder if there were other obvious-in-hindsight bad/weird/hackish choices in classic computer design?

The PC-AT's use of the keyboard controller to control A20 and CPU reset comes to mind.

Any others?

[Jeema101]

Several video game consoles from back in the day (the Magnavox Odyssey 2 and Entex Adventurevision) used the MCS-48 microcontroller mentioned in this write up instead of more conventional CPUs of the time like the 6502 or Z80, which seems a bit strange.

Having dabbled in both MCS-48 and 6502 assembly I can tell you it was probably not done to make software development easier. :) I suspect maybe the hardware was just easier to design around a microcontroller? ...but there could have been other reasons...

[Marazan]

Both the 6502 and Z80 were designed/imagined for use in embedded systems, not the general purpose computers they became famous in.