Re: Apple II C start-up disc.

[bjbear@ibm.net (B.J. Major & Dennis J. Gorin)]

In article <5j30cf$18ls@uni.library.ucla.edu>, pubpc1@library.ucla.edu wrote:

> Andrew Roughan <posty@203.triode.net.au> wrote:
> >
> >Randy Shackelford <shack@deimos.frii.com> wrote:
> >> >BJ, unless a //c has the earliest motherboard, which has a timing
> >> >defect, the port can drive a 14.4Kbaud modem fine.  You can also
> >> >hook up a faster than 14.4 modem, but the port speed is limited
> >> >to 19200, so you don't gain anything.
> >
> >> Since //c's have no flow control, and the port goes from 9600 to 19200, 
> >> there is no way to run a 14400 at higher than 9600.
> >
> >That's not strictly correct. Hopefully this will elaborate on the situation:
> >
> >If you have a //c which runs fast enough, then you should lose no characters
> >while the port is running at 19.2k, however, in practice, the standard //c 
> >will not keep up sufficiently at this speed.
> >
> >There are no pins available for * Hardware * flow control, however the //c
> >can use XON/XOFF flow control with software which supports it. This may
> >allow a //c to keep up with 19.2k while you are not making heavy use
> >of the downlink....
> >
> >However in practice for a reliable session you'd probably set the port speed
> >to 9600. The modem may try and negotiate 14.4k with the other side
> >but if it does you'll soon blow the modems internal buffer and lose
> >characters or even lose your connection with any kind of modem error
> >checking enabled.
> >
> >Therefore you'll want to limit your 14.4k modem to 9600.
> 
> Well, on a Laser 128EX or EX/2 computer, which runs a 3X the
> //c and uses the same modem cable as the //c, 14.4k works fine.
> 
> However, even if it is true that a standard //c without a ZipChip
> is practically limited to 9600, 9600 is still four times faster
> than 2400.
> 
> None of this applies to the IIc+, of course, which is more than
> fast enough to do 14.4k and uses the same cable as the GS/Mac.
> 
> -Scott G.

All of the above is a moot point for me--and comparing the Laser computer,
which never had a timing crystal problem--to the //c is ridiculous.  I have
two of the oldest //c's made and they simply cannot use a modem faster than
2400 baud.  I've tried it.  I would have upgraded the motherboard for free
from Apple, but found out about it years too late.

-- 
--bj
Apple //--///--Macintosh user/supporter/collector