18 Oct
2007
18 Oct
'07
12:20 p.m.
Tony Duell wrote:
SOme 8-bit home micros -- the Commodore PETs/VIC20/C64/C128 and the BBC
micro being the obvious examples, had an uncommitted 8 bit parallel I/O
port that was essentially half of a 6522 VIA. The Tatung Einstein had a
similar port that was half of a Z80-PIO. In all cases the external
connector was labelled 'User Port'.
THe idea was to have an port that could be used for simple homebrew
control/sensing applications. You could easilly hook up switches,
transistors-driving-relays and so on.
Very few later machines had them. The Sirius/Victor 9000 did -- a full
6522 on an unmarkerd header inside. The PC printer prot is nowhere near
as versatile IMHO.
-tony
And how many PCs have a 'user port'?
That's one thing I would certainly
want to hack in somehow.
What is a "user port"?