ZX80, ZX81, Spectrum, Acorn Acom, Acorn Electron, BBC Micro, etc, etc.
Do you count machines like the Amstrad CPC464 which had a built-in
cassette recorder?
And don't forget the Commodore cassette port - used on the PET, VIC,
C64, ...
This blurred the line between built-in cassette drives and cassette
ports, since the built-in drive on early PETs became the separate drive
on later ones, plugging into the same port.
This didn't just switch the motor, it powered it from the computer.
Also unusual, I think, was that it didn't use a modem chip to generate
tones, but bit-banged them in software.
Philip.
