Re: Apple II modem question: How can you go at 19200 when apple II isnt this fast?

[spec@vax2.concordia.ca (Mitchell Spector)]

In article "Brian J. Bernstein" <bernstbj@ix.netcom.com> writes...

>itsme wrote:
>> 
>> I don't think that an apple II can even think at 9600 bps.  (tell me if I
>> am wrong)
>> 
>> Maybe it can, but 19200?  (tell me if it can)
>> 
>> Does a serial card do buffering so the apple can handle information coming
>> in at these speeds, or can it in fact process information or at least
>> store it when data is at this speed?
> 
>  Well, I'll say this from my experience.  Note that this is regarding
>an UNACCELERATED ][ (ala 1.024 MHz 6502/65C02)
> 
>  Receiving at 19,200bps using Zmodem doesn't always work too well
>(null-modem)
> 
>  Since the disk drives disable interrupts, any receiving of data during
>a read/write is garbled
> 
>  Accelerated ]['s have little to no problem with 19,200 (as above)

    My Apple IIc Plus (4 MHz) cannot reliably use a modem at more than 
9600 bps, trying to connect at 14400 causes loss of characters and some
other strange oddities to occur (like ProTERM locking up constantly).
This probably has more to do with the serial port, controlled by a
6551 and which has only 4 signals presents (one of the 5 pins used 
is a ground if I remember right).

    It is probably a different story for an Apple II+/e equipped with
a Super Serial Card, there are more signals present through it's pin
connector. I never got around to finding a serial cable, so I've not
tested my SSC with a high-speed modem yet.

Mitchell Spector
spec@vax2.concordia.ca