sfw@dvamc.UUCP (01/06/84)
CBM vs RS232 Peripherals Connecting any RS-232 device to the 64 or VIC is an exercise in frustration if not futility. CBM managed to totaly mung the implementation of RS-232 in such a way that it is impossible to reliably use the serial port devices such as printer and disk while using the RS-232 port. This is due to the fact that the RS-232 software UART uses the NMI and the serial port software UART uses the NMI as well. The guru's of Commodore did not see fit to interface the two properly to eliminate bus conflicts. The only way I have found around the problem is to buffer the input from the RS-232 into RAM and then print out the contents to printer or disk when the RS-232 is guaranteed quiescent (i.e. the host program is waiting to receive input from the VIC or 64). If anyone else has had similar difficulties and/or alternative solutions to this problem your input would be most welcome. Sue F. Woodbury (duke!dvamc!sfw)
miller@uiucdcs.UUCP (miller ) (01/16/84)
#R:dvamc:-111000:uiucdcs:36100027:000:808 uiucdcs!miller Jan 16 00:35:00 1984 Gee, I have not had any problem using the disk and RS232 at the same time with one exception: you CANNOT use the RS232 at the same time the so called "wedge" (hereafter refered to as "kludge") is active. Why? Because both the RS232 kernal routines and the kludge program supplied with your 1541 use the cassette buffer for temporary storage. All sorts of weird things occurred to me before I found that out. I almost always use the new VT-52 emulation program. But occasionally, I dust off my old simple Basic terminal program I wrote as it allows uploading of disk files. The base note mentioned downloading. I've never tried that so I can't say for sure there are no problems. All I know is, as long as the kludge is not active, I've never had any problems uploading files off disk. A. Ray Miller