On Tue, Jan 31, 2023 at 10:56 AM Philip Belben via cctalk <cctalk@classiccmp.org> wrote: > > > 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, ...
I think somebody else mentioned that one. > > 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. When I got my first PET, I didn't have the Commodore casstte recorder for it. So I designed a simple interface to link a normal cassette recorder to the PET's edge connector. I used the motor drive line to operate a relay with the contacts going to the remote socket on the cassette unit. Since the cassette recorder I was using (a Radio Shack CCR-82) had the +ve battery line going to the internal on-off switch, then to the remote socket, then to the motor, I could sense the voltage on the appropriate side of the remote socket to indicate when the 'Play' key was pressed and use that to switch a transistor connected to the PET's cassette switch pin. > > Also unusual, I think, was that it didn't use a modem chip to generate > tones, but bit-banged them in software. Almost all 8-bit home micros bit-banged the tones, and also decoded them in software. I think the BBC micro (and Electron?) was the common exception in the UK. -tony
