20 Sep
2006
20 Sep
'06
12:06 p.m.
Cameron Kaiser wrote:
You can get 9600 in 64 mode if you tweak the user port interface to feed
the incoming bit stream into the CIA shift register. The mod is called
the Daniel Dallmann mod (after the creator) or UP232 (after the novaterm
terminology), and ez232 contains jumpers to reconfigure for normal or
UP232 mode
Jim
--
Jim Brain, Brain Innovations
brain at jbrain.com
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!
Home: http://www.jbrain.com
I've so
far run at 1200 baud, I think it's good for somewhere between
2400 and 9600 baud, from what I've read, but am not sure. I gather
some tricks are needed to get much faster than 2400 out of a C64 User
port. Others here would know a lot more than me about this.
There are some bitbanger routines that entirely bypass NMIs and busy-drive
the user port. Obviously they completely occupy the CPU and are no good
for interactive applications, but they work well for file-transfers. Over5
(google for it) is one of these.
128s in 2MHz mode can drive the user port at 9600 using custom software.
DesTerm and NovaTerm both have this capability.