From: Ethan Dicks (ethan.dicks_at_gmail.com)
Date: 2009-01-29 06:59:39
On Thu, Jan 29, 2009 at 12:49 AM, William Levak <wlevak@sdf.lonestar.org> wrote:
> The SP has a serial port inside (DB25 connector). A few years ago I did get
> it to work at 300 baud. It did not work at higher speeds. One problem was
> that it required a 2-4 second line delay (time after sending a return until
> it was ready again).
Was this from BASIC or other high-level language? ISTR there's just a
6850 or 6551 ACIA-type UART in there, so from machine language, it
should be trivial to drive at 9600 bps.
I didn't get to play with serial back in the PET days - my first
exposure was a VICmodem on a C-64 c. 1982 (i.e. - when the machine was
really, really new). Even with software bitbanging, I used my
VICmodem with a terminal emulator I wrote in BASIC (since the one on
the cassette in the box was so terrible for CompuServe). I eventually
did get an IEEE-488-based serial interface for the PET, but not until
many years later when such things didn't matter.
It would be strange to learn that the serial interface in the SuperPET
didn't work faster than 300bps, but perhaps they figured it'd only be
used for contemporary modems, so it didn't have to be efficient.
-ethan
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