hoang@rex.cs.tulane.edu (Dzung Hoang) (06/24/89)
A friend of mine has a 2400 baud RS232 modem that is connected to his C-64 through an Aprotek modem converter. He can get the modem to work fine at 300 and 1200 baud, but at 2400 baud, extraneous characters start to appear and he can't even send the AT command to the modem. Is this a problem with the modem, the interface, or the C-64? I have a feeling that the C-64 is not fast enough to handle 2400 baud. Any help would be appreciated. Reply to the address below. Dzung Hoang hoang@comus.cs.tulane.edu tulane!comus!hoang
jgreco@csd4.milw.wisc.edu (Joe Greco) (06/24/89)
In comp.sys.cbm article <853@rex.cs.tulane.edu>, hoang@rex.UUCP (Dzung Hoang) wrote: ] ] A friend of mine has a 2400 baud RS232 modem that is connected to his ]C-64 through an Aprotek modem converter. He can get the modem to work fine ]at 300 and 1200 baud, but at 2400 baud, extraneous characters start to ]appear and he can't even send the AT command to the modem. Is this a ]problem with the modem, the interface, or the C-64? I have a feeling that ]the C-64 is not fast enough to handle 2400 baud. Any help would be ]appreciated. Reply to the address below. ] ]Dzung Hoang ]hoang@comus.cs.tulane.edu ]tulane!comus!hoang ] I've found that my Courier (US Robotics) modems appear to tie the received data and transmitted data lines together in Command Mode. This means that when the computer causes a transition on the TX line, it immediately receives an interrupt because of the transition coming back on the RX line. This seems to cause some heartache to the RS232 routines (even Geoff's), so I have found it best to run with Echo Off in command mode (ATE0, I believe). I had no problems after that. If the Courier received an entire character and then retransmitted it to the computer, there would be no problem.... Perhaps your friend is experiencing similar troubles. Try ATE0 (or better yet, set switches to default to Echo Off). cc: to the address above. -- jgreco@csd4.milw.wisc.edu Joe Greco at FidoNet 1:154/200 USnail: 9905 W Montana Ave PunterNet Node 30 or 31 West Allis, WI 53227-3329 "These aren't anybody's opinions." Voice: 414/321-6184 Data: 414/321-9287 (Happy Hacker's BBS)