Path: utzoo!attcan!utgpu!watmath!att!dptg!rutgers!cs.utexas.edu!uunet!mcvax!ukc!axion!tigger!cag From: cag@tigger.planet.bt.co.uk (Chris Green) Newsgroups: comp.dcom.modems Subject: Re: Minitel videotex terminals and v.23 Message-ID: <528@tigger.planet.bt.co.uk> Date: 28 Jul 89 08:19:20 GMT References: <817@sbsvax.UUCP> Organization: RT5111, BTRL, Martlesham Heath, England Lines: 35 > In article <431@siswat.UUCP>, buck@siswat.UUCP (A. Lester Buck) writes: >> It seems that v.23 modems are quite expensive, around $800 and available >> only in Europe. Since the Minitel only costs something like $70-80, this is >> something of a problem. Assuming v.23 is basically 1200 baud in, 75 baud >> out, what are the possibilities of using standard 1200 baud modem chips? > There certainly are reasonably priced v21, v22, v22b and v23 modems available, the one that immediately comes to mind is the (internal PC) Amstrad MC2400 at about 170 pounds sterling and a similar external model by Amstrad (SM2400 ?) at maybe 50 pounds more. These Amstrad modems (and most other recent ones) have internal buffering to allow the modem to PC link to run at 1200/1200 while the modem to modem link runs at 1200/75. It is possible to find v21/v23 only modems (rather old technology now) very cheaply indeed, mainly because Prestel and others gave them away with Prestel subscriptions. The main problem with these is that they are not buffered and thus need a PC with a split speed serial port. A standard IBM PC cannot do this so comms programs which can use these older modems have to have a software kludge to transmit at 75 while receiving at 1200. It can be done (I have a comms program called TranSend which does it very successfully and emulates Viewdata on a Hercules display) but it is not simple. You could probably get a V21/23 modem for about thirty pounds sterling and add about the same again for a program to handle the unbuffered modem and you could probably do Viewdata on a PC for about $100. Just need a friend in the U.K. to go shopping for you. If the requirement is a one off (or so) I wouldn't mind helping. By the way Prestel is now almost universally available at V22b so the requirement for V23 modems is steadily tailing off now, I suspect that it will soon be a thing of the past. Chris Green cag@planet.bt.co.uk