trejo@NPRDC.ARPA.UUCP (02/11/87)
I have an Apple IIc that I'd like to use as a terminal that talks to a VAX or a Masscomp over a local high speed modem (9600 baud). Does anyone out there know of software that will do this using the modem (or other) port on the Apple IIc? Something like VT52 or VT100 emulation would be fine. Len Trejo trejo@nprdc.arpa Phone (619) 225-7424
schumann@puff.UUCP (02/16/87)
In article <8702111802.AA00876@nprdc.arpa>, trejo@NPRDC.ARPA writes: > I have an Apple IIc that I'd like to use as a terminal that talks to > a VAX or a Masscomp over a local high speed modem (9600 baud).... > ... Something like VT52 or VT100 emulation would be fine. The Apple //c will have a VERY difficult time recieving data at 9600 baud. One character at 9600 takes 1/960th sec (1.042 ms) +/- 2%. Using iterrupt mode, the //c can take up to 300 microseconds to respond, add about 40 for ProDOS (assuming priority one), 100 to queue the character, and add up to 140 for the //c to return to the interrupted program. That comes to 580 microseconds or almost 56% time spent on queueing characters, never mind printing them. I have found the //c can go up to 3600 with no difficulty, and 7200 in a pinch. You could write your own interrupt handlers, and replace the interrupt vectors in bank-switched ram at $FFFE, which automatically get changed to point to the ROM handler when just about anything happens (an exaggeration). Anyway, I know of at least three 9600 baud modems. Racal-Vadic 9600VP 9600,7200,4800 $1495 V.29 EVI UPTA 96 9600,7200,4800 $895 V.29 Telebit Trailblazer 9600 $2300 Special
ranger@ecsvax.UUCP (02/19/87)
I have used Softerm // on a //c connected to a VAX running at 9600 baud
with no problems whatsoever. Even if it takes that much CPU time to
handle interrupts on the //c, the 34% left is more than enough to handle
a simple task like terminal emulation. The only thing that limits the
//c in this area is bad software.
Rick Fincher
ranger@ecsvax
> The Apple //c will have a VERY difficult time recieving data at 9600 baud.