grwalter@watmath.UUCP (Fred Walter) (08/02/86)
Query: has anyone had any experience using a 2400 baud modem with a C64
or a C128 ? Can either of these computers support 2400 baud, even in
machine language ? I know a lot of software describes itself as supporting
300/1200/2400 baud, but I know that some of the software which states it will
support 2400 baud has never been tested at 2400 baud.
Any replies will be appreciated ...
fred
UUCP : {allegra|clyde|linus|decvax|utzoo|ihnp4}!watmath!grwalter
CSNET : grwalter%watmath@waterloo.csnet
ARPA : grwalter%watmath%waterloo.csnet@csnet-relay.arpaporter@cbmvax.cbm.UUCP (Jeff Porter) (08/10/86)
> In article <2050@watmath.UUCP> grwalter@watmath.UUCP (Fred Walter) writes: > > Actually, what is needed is a hardware UART. I have diddled with > perhaps taking an Intel chip and hanging it off the user port, using > the timer as the bit clock, but haven't attempted it yet. A 6800/6500 > family chip would be very difficult to hang off the user port, since > it would be a synchronous chip (needing a 1 Mhz. clock to operate and > expecting its operands within that clock). > What you need to do is hang the UART off the CARTRIDGE PORT not the USER PORT. A 6551 will do nicely. You will however need to write your own software to look at this different location for the UART. This UART is software selectable to 19.2K baud, but I will wager that you run into crunching power before this (esp. with a smart terminal emulator). Jeff Porter Commodore Engineering
hindmost@mit-trillian.MIT.EDU (Brian R. Murphy) (08/10/86)
In article <865@usl.UUCP> elg@usl.UUCP (Eric Lee Green) writes: >In article <2050@watmath.UUCP> grwalter@watmath.UUCP (Fred Walter) writes: >>Query: has anyone had any experience using a 2400 baud modem with a C64 >>or a C128 ? Can either of these computers support 2400 baud, even in > >2400 baud is impossible on a C-64, unless you totally chunk all Kernal >routines (in which case it would STILL be extremely unreliable, and >you would be limited to 40 columns because 80-column emulation is too >slow even for 1200 baud). I don't think you'd be limited to 40-columns. The 80-column screen does slow it down (I can't remember how much cpu it steals right now, but a terminal emulator I wrote using kernal routines never made it past 600 baud or so with software 80-columns), but not that much. I took a look at the routines, and they seemed to leave much room for improvement, so with your own it seems like you could do it. If anyone already has these, it would be nice if you'd post them. >Commodore personel have stated that 2400 baud is possible on a C-128 >while running in 80 column mode at 2Mhz. I am not qualified to judge >the truthfulness of this statement, since I do not have a 2400 baud >modem and have only had a C-128 for 3 weeks. It does seem rational, >though... processor twice as fast, baud rate twice as fast, and with >the 128's real 80 column screen, no problem emulating a "smart" >terminal. 2400 baud does work on the 128; I converted a terminal emulator I wrote, using standard kernal rs-232 routines, on the 64 with few problems recently. It seemed unreliable at 1mhz and 2400 baud, even using the nice hardware scrolling in the VDC (really burns compared to anything without it), but at 2mhz it works perfectly, with an Anchor 2400 baud modem (which I've had no problems with). I'm working on a vt-220 emulator now, and I hope I can get it faster than 2400 baud using custom low-level i/o. Any suggestions? -Brian Murphy hindmost@athena.mit.edu { decvax!genrad, ihnp4 }!mit-eddie!mit-athena!hindmost
rayz@csustan.UUCP (R. L. Zarling) (08/11/86)
In article <2050@watmath.UUCP> grwalter@watmath.UUCP (Fred Walter) writes: >Query: has anyone had any experience using a 2400 baud modem with a C64 >or a C128 ? Can either of these computers support 2400 baud, even in 2400 baud will be flakey on either machine any time the VIC chip is running. It steals the bus for 40 ms every eighth scan line, and the rs232 NMI's can therefore get to the 6510 late. With some hosts, this effect is even noticable at 1200 baud, but it is totally out of hand at 2400. With the 128 in fast mode, the VIC chip is automatically turned off, so there is no problem.
elg@usl.UUCP (Eric Lee Green) (08/12/86)
In article <2050@watmath.UUCP> grwalter@watmath.UUCP (Fred Walter) writes: >Query: has anyone had any experience using a 2400 baud modem with a C64 >or a C128 ? Can either of these computers support 2400 baud, even in 2400 baud is impossible on a C-64, unless you totally chunk all Kernal routines (in which case it would STILL be extremely unreliable, and you would be limited to 40 columns because 80-column emulation is too slow even for 1200 baud). Commodore personel have stated that 2400 baud is possible on a C-128 while running in 80 column mode at 2Mhz. I am not qualified to judge the truthfulness of this statement, since I do not have a 2400 baud modem and have only had a C-128 for 3 weeks. It does seem rational, though... processor twice as fast, baud rate twice as fast, and with the 128's real 80 column screen, no problem emulating a "smart" terminal. Actually, what is needed is a hardware UART. I have diddled with perhaps taking an Intel chip and hanging it off the user port, using the timer as the bit clock, but haven't attempted it yet. A 6800/6500 family chip would be very difficult to hang off the user port, since it would be a synchronous chip (needing a 1 Mhz. clock to operate and expecting its operands within that clock). -- -- Computing from the Bayous, -- Eric Green {akgua,ut-sally}!usl!elg (Snail Mail P.O. Box 92191, Lafayette, LA 70509)
mcewan@uiucdcsb.CS.UIUC.EDU (08/13/86)
>>Query: has anyone had any experience using a 2400 baud modem with a C64 >>or a C128 ? Can either of these computers support 2400 baud, even in > >2400 baud is impossible on a C-64, unless you totally chunk all Kernal >routines (in which case it would STILL be extremely unreliable, and >you would be limited to 40 columns because 80-column emulation is too >slow even for 1200 baud). Then I must have been hallucinating when I thought I was seeing 80 columns at 1200 baud on my C64 (this was kermit's 80 column VT52 emulation and a 1670 modem. It didn't lose any characters and sure seemed to be going at full 1200 baud, although I didn't time it.) Scott McEwan {ihnp4,pur-ee}!uiucdcs!mcewan "Me always knew this day would never come! That why me prepared for it!"
rayz@csustan.UUCP (R. L. Zarling) (08/14/86)
In article <47900003@convex> danny@convex.UUCP writes: >Racal-Vadic and Multics make CCITT V22.bis faithful modems. USRobotics >doesn't. Have a good look. > According to my manual for my USRobotics Courier 2400 modem (p. 1-3): "...is Bell 103-, 113-, 212A-compatible, V.22 bis-compatible, ..." What's going on? Do we have a problem with the word "compatible" here (again)?