15 Aug
2005
15 Aug
'05
6:05 p.m.
An early example of a bit banger serial interface was the Motorola 6800
MIKBUG Monitor ROM. It used a parallel interface chip (MC6820 PIA) as a
bidirectional serial interface. It would work at 110 and 300 baud (some
people clocked it at 1200 baud.) This was the used in original (1975)
Southwest Technical Products 6800 computer. Motorola had a real UART (MC6850
ACIA) at the time so I don't know why Motorola did this. SWTPC later
switched the their own Monitor ROM and a MC6850 serial port.
http://www.swtpc.com/mholley/swtpc_6800.htm
Michael Holley