mike2@lcuxa.UUCP (M S Slomin) (11/20/86)
My kids have a C-64 that their daddy occasionally uses for serious work (and playing). It has had a 300 baud modem for several years, and we've acquired a fair amount of terminal software for it, including capabilities for transferring files under the Punter, xmodem and Kermit protocols. But, of course, 300 baud is painfully slow. Yet, given the obvious limitations of the C-64, I've been unwilling to spend any more money on it to ameliorate this. I finally broke down and bought a Volksmodem 1200/300 baud modem for it, since it only cost $80 (from Protecto). When it arrived yesterday I put it though its paces. I'm returning it today, and I thought I'd alert others to the reasons for doing so: 1. The Volksmodem's hardware interface differs from those used by the various "standard" modems (e.g., CBM, HES, and Total Telecom). Therefore, the various public domain terminal programs will **not** communicate with it. Not for dialing. Not for terminal mode (see #2 below). 2. There are no switches on the Volksmodem. Placing it off-hook, and selecting its speed (300 or 1200), are done through the hardware interface. Therefore, you cannot use other terminal programs along with manual dialing on a nearby telephone, since these programs do not send the appropriate control information to the Volksmodem to get it off hook and to select its speed. 3. The software that comes with it makes speed selection rather difficult. Speed is but one attribute, along with character bits, stop bits and parity, all of which cannot be selected independently. Rather, one must scroll through a menu of combinations of these. So, to do the simple 1200-7-E to 300-7-N relatively common switch, one must remember to scroll it eight times (or is it nine?). And, in autoanswer mode, it will only talk to a calling computer that matches its previously-selected setting. 4. The only error-checking protocol resident in the software is checksum-Xmodem (with or without CBMascii-ASCII conversion). No Punter. No Kermit. All of the "deadly embrace" possibilities of classic Xmodem, compounded by #5 below. 5. It's not precisely on frequency. You can modify the clock rate used by the C-64's equivalent of a UART, just as Steve Punter did in the original TERMINAL.C1/V2 program that has spawned so many others, rather than using CBM's (incorrect) pre-programmed numbers, but it only helps somewhat. On a 3 mile long local connection to my company's MICOM switch/modems at 1200 baud, it was running about a 5% character error rate at best, after I'd twiddled the clock number to the optimum. I never could get it to talk to the PC-XT/Hayes/Procomm2.4 combination to see whether the error rate would be worse with a less expensive (and presumably less forgiving modem) at the other end, see #6. 6. The latest Procomm "host" mode can detect the incoming call's speed by sensing for multiple carriage returns (or spaces). Problem: the Volksmodem won't transmit until **it** senses a matching tone at the called end. Therefore, the Volksmodem won't send the C/Rs, and the other end won't adapt. This is by no means limited to Procomm2.4 implementations; many 300/1200 baud BBS' operate the same way. This is probably a limitation in the Volksmodem's software, but since no other terminal software works with it, it is a real limitation. 7. Finally, there is supposed to be flow control in the Volksmodem software (optional), but it didn't work properly. Sometimes it worked; othertimes it didn't. In any event, flow control should not be necessary when accessing a UNIX system at 1200 baud, but it proved to be. Perhaps they wrote the software in compiled basic rather than assembler, as it should have been written, and it's not keeping up adequately. The product is not worth the effort to find out. BOTTOM LINE: It may be cheap, but apparently you get what you pay for. You can't use it with any pre-existing software, nor with conventional file transfer protocols. It may well have hardware problems, in view of the observed error rates. And, its own software is not very good. Be warned. ************************************************************************ Disclaimer: The foregoing views are my own, and mine alone. No one else is even interested in them.