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Faster Serial Ports - All older apples
There's a program called Apple 2 Serial for the PC that works (cringe) by
emulating a 9600 baud serial port thru the CASSETTE adapters! Its PC
COMPONENT, the file aplserv.exe, acts as a "disk server" for all drives
except 6. Modify your dos and suddenly there's over 500 "virtual disks"
available on the PC.
Coolness. But I had a 2C I wanted to use it on... so I took the guys
Apple 2 source and rewrote it to work with the serial ports on the 2C.
Easy enough. 9600 baud was too slow for my taste, so I locked my PC com 2
at 19.2K with a FOSSIL driver called BNU.SYS and made the Apple 2C run my
program (SerialNET) at 19.2K as well.
I'm still not happy enough... :)
The serial 'cards' on the 2C us an ACIA labeled:
338-6551
R6551-22
8506
Okay, so its obvious the chip is a 6551, a standard extension for the
65xx microprocessor series, one presumes.
It runs on a 1.8432MHz crystal. At first I was simply going to upspeed
the crystal itself (might have worked) until it occured to me that the
chip uses the crystal to divide out a frequency, *and* that 1.8432MHz is
a lot faster than the upper limit of 19.2K on an Apple serial port.
Thumbing thru a bunch of crystals a friend has for his PC, I was sort of
shocked to notice a number of 1.8432MHz crystals there as well. Okay...
Only 4 bits are used by the SSC (or the apple 2c?) to divide the crystal
frequency, and the 2C apparently starts from 19.2K and divides down from
there. What I'm wondering is if there aren't maybe some bits or something
going to that chip on the motherboard that can be altered, giving a
different divisor/etc. If not, is there anything else that can be done???
--
____ ______ ________ _____
/ \ | \| /\ | \ jkenner@cello.gina.calstate.edu
/ \| _ \ \/ | _ \
/___/\ \___|> > |__|> > BORN TO BE WIRED...
/ | / /\ | / All the sugar and twice the
\_________|______/|___\/__|______/ caffeine of regular netusers!
finger me and make a pgp key come.