Re: Apple Serial vs Super Serial

[dempson@actrix.gen.nz (David Empson)]

In article <15JUN199402003228@vax2.concordia.ca>,
Mitchell Spector <spector@vax2.concordia.ca> wrote:
> 	Can someone tell me the major differences between the original
> "Apple Serial Interface Card" and the later "Apple Super Serial Card"? 

Yes.  The original Apple Serial Card is a pretty amazing piece of
work.  It has no serial chip (UART/ACIA) and does all of the serial
data handling in software.  It can only support half duplex
communcations (one way at a time) and you have to use the firmware on
the card (or duplicate its function in your own programs).  It doesn't
support interrupts (a meaningless concept, since there is no hardware
to generate an interrupt).

The Super Serial Card has a dedicated serial chip (6551 ACIA).  The
firmware on the card provides a command set which is based on the
Apple Serial Card and the Apple Communciations Card (which I know
nothing about).  Full duplex (simultaneous bidirectional comms) is
supported.  The firmware on the card can easily be bypassed, and comms
programs can use interrupts with the card.

I don't know of any comms programs that would support the Apple Serial
Card.  It is basically useless, except for sending data to a printer.

Hope that helps.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand