24 Aug
2006
24 Aug
'06
1 a.m.
Hi,
Tony Duell said:
Actually, those CPU I/O lines _are_ useful. Remember on the MK14 that the
8154 chip was _optional_. Without it, that's all the I/O you get.
IIRC that cassette interface (which I never got to work properly...) used
one of the flag lines as the output (record) and one of the sense lines
together with the serial input line (strapped together) as the input
(playback).
Yep, flag zero for record and sense B and SIN for play. (I still have
the manuals and diagrams on my desk here from when I was looking stuff
up the other day.)
My cassete interface works fine, I loaded a program with it when I
was digging the manual out, but it's a bit fussy as to level.
--
Cheers,
Stan Barr stanb at dial.pipex.com
The future was never like this!
The SC/MP has some I/O lines on the chip. IIRC there
are 3 flag outputs
(on/off signals controlled by bits in the CPU status register), 2 sense
inputs (which can be read as bits in the CPU status register, one can
also be used as an interrupt line), and serial I/O lines which go to the
'ends' of the CPU extenstion register (which can be shifted under program
control). These lines _are_ brought out to the connector at the back.
But the CPU buses aren't.
Ah, the useful stuff, then :o|