Date   : Mon, 18 Mar 1985 20:32:00-EST
From   : ABN.ISCAMS@USC-ISID.ARPA
Subject: Re: Port I/O from MBASIC...

Jordan,

When I absolutely had to (on this Morrow Decision of mine), I used the
MBASIC INP and OUT to work with the Morrow ports.

Mine is weird because you must poke (well, OUT) a value to one location
to flip the I/O board to that port "family", and THEN INP another
location to check port status (doing various masking for ready condition),
and THEN OUT a third location to shoot the port!  Ugh!

If you have source code for your BIOS, check the CONIN and CONOUT, LISTOUT,
PUNOUT, etc.  They all deal with ports in, out, ready/busy, and you can
pick up the AND masking values there.  (Also the addresses.)

All my port addresses are low (less than 80H, naturally), and can be
addressed as integers, so INP and OUT work fine.

However anything heavy going on (lots of fast changing status), and BASIC
is just too slow to do that INP/OUTing very well.

Now if I were only more knowledgeable on interfacing machine language
programs with MBASIC... Much rather do the tricky stuff there and hand
values to and from the ML segment.

Hope this was some help.

Regards,
David Kirschbaum
Toad Hall
(ABN.ISCAMS@USC-ISID)