hong@garfield.UUCP (03/10/86)
I want to add an interface for a Hayes compt modem. And I was told by someone there are a lot of serial interface availiable , but I have no idea which will suit my requirement. There are Atari 850, P:R CONNECTION (100 % 850 compt?), U-CALL and R-VERTER. Have you used any of the above? Which one is better? Thanks in advance.
jhs@MITRE-BEDFORD.ARPA (03/14/86)
The 850 interface from Atari has 4 serial (cereal?) ports and one Centronics-type parallel port. One of the serial ports can be made into a 20-mA current loop to run old fashioned Teletypes if you wish. I bought an 850 a couple of months ago from CSC, Inc., Hightstown NJ. Their phone is (609) 448-8889. Their price for the 850 was the standard $109.00. The Centronics port plugged in and ran a borrowed Epson printer with no problems. I bought an assembled cable, incidentally, from CSC for $25.00. You can make one but you will spend at least $15 in parts unless you have a source of connectors at very low cost. INTERESTING NOTE for Atari fans... the 850 I bought came in the "new" color of the 130XE/520ST. This makes me suspect that a new production run has started and that rumors of unavailability of this product are "greatly exaggerated" to paraphrase Mark Twain. I would emphatically NOT recommend that anybody get suckered in to paying $149.00 for this interface as I have seen some suppliers cheerfully suggest. The P: R: connection looks like a reasonable alternative. It has I believe only two serial ports but that's probably more than most people will ever use. It DOES NOT require a power transformer like the Atari one as it steals power out of the Atari serial bus pins. Presumably this will not greatly increase the load on the Atari's transformer, but then again it sure won't decrease it! This one sells for around $60. I have not used the others you mentioned but I am sure they would work fine assuming the cable from them to your modem was wired suitably. However, with the above two interfaces you get a parallel printer port as well as the serial ports. One other product should be mentioned: I think it is Astra Systems that makes a very nice disk drive which also throws in I believe one serial and one parallel port. (Somebody else may have more details). If you want another disk drive also, this is a very reasonable thing to consider. But it is not a cheap way to get just the serial port! NOTE that RS-232-C ports, while they have 25 pins, use only about 6 of them in practice. It is not too bad a job to wire up a cable, and this might be a good place to save some money. Also, the ribbon cable approach is even easier despite the fact that it wires up all 25! Hope the above is of help.
JEB6589@RITVAXB.BITNET (03/18/86)
I have the R-Verter interface, you mentioned. It is a very simple interface and does not support true RS-232 levels. Most manufactures consider 0 volts a logic 1 and +5 a logic 0 so they can get away with this. The RS-232 standard states that a logic 1 is -5 to -15 volts and a logic 0 is +5 to +15 volts. So consequently the R-verter is not compatible with every modem along with the fact it does NOT support DTR. Also the 850 and P:R: connection allow the daisy chaining of peripherals, while the R-verter doesn't. The U-call interface from digital devices I am not sure about. I am a member of DELPHI and there has been alot of discussion of the compatability of the P:R: Connectio n and the 850, it is 100% CIO compatible, not SIO though, as this would cause copyright infringement, or so the discussion goes. Jim Berg Jeb6589@ritvaxc.BITNET