lamia@topcat.DEC (Walt Lamia MKO1-1/A11 264-7772) (04/05/84)
(sacrificial token offering)
There seem to be a fair number of low-cost printers coming on
the market these days, but mostly they come with parallel interfaces,
for use mainly on IBM-type micros. I think the prices of the RS232
serializers are outrageously high, so I'd like to ask if anyone in
net-land knows of a cheap way to build such a device. Are there neat
chip sets that could be brewed up into an interface? Any suggestions
or pointers to articles in publications would be appreciated.
If there is enough interest, I will post summaries of replies.
Thanks as always,
Walter Lamia
UUCP: ...{decvax,allegra,ucbvax}!decwrl!rhea!topcat!lamia
ARPA: decwrl!rhea!topcat!lamia@SU-Shastamatt@UCLA-LOCUS.ARPA (04/11/84)
From: Matthew J. Weinstein <matt@UCLA-LOCUS.ARPA> A great service would be performed if someone would develop a single chip-based serial to parallel circuit. Any sort of UVPROM type combined processor-i/o chip with a reasonable number of i/o pins would probably be fine. Serial-parallel conversion at fairly high baud rates can be accomplished in software; very simple flow control would have to be implemented, and fancy buffering for folks with extra $$ for memory could be done too. Putting this sort of thing in the public domain would be a great service (and save a lot of money). If I had time I'd do it myself. - Matt
Fat.Tag@SU-SIERRA.ARPA (04/11/84)
From: Tim Gonsalves <Fat.Tag@SU-SIERRA.ARPA> The Apr 84 issue of REMARK (Heath Users Group magazine) has an RS-232 - Centronics converter circuit. Uses a UART + 3 TTL chips + crystal. Supposed to work at 9600 baud. Cost ~ $25. (REMARK is available in Heathkit Electronic Centers). Tim Gonsalves -------
BILLW@Sri-Kl.ARPA (04/12/84)
@flame( What you want is a serial to parrallel converter, not a parallel
to serial converter!)
There was an article describing an extremely clever serial to parrallel
converter in the December, 1983 issue of "microcomputing" magazine
('solution to a serial saga', by Frank Sergeant, page 102). It uses
an 1802 uProcessor, a ROM, a hex inverter, and an 1852 parrallel latch.
The circuit is designed with CoCo in mind, and does rely on the computer
having a hardware handshaking line on its serial port...
BillWemjhm@uokvax.UUCP (04/15/84)
#R:decwrl:-685800:uokvax:3400040:000:667 uokvax!emjhm Apr 14 21:43:00 1984 Walter, If you can buy an AY-3-1015 and get hold of an application note for this device, building a serial to parallel converter is fairly simple. The Radio Shack part number is 276-1794 and costs five or six dollars. It has the circuit diagram and a small ap note attached to it. You can run it with either a 556 type timer or if you want to spend another 5 bucks you can build a crystal controlled clock with a CD4060 and a 2.4576 MHz crystal. The whole thing shouldn't run more than about 15.00 if you wire wrap it. If you want the schematic, try to get a message to me at ...!ctvax!uokvax!emjhm and I'll give you an address to send a SASE to. Jim Miller
mzp@uicsg.UUCP (04/18/84)
#R:sri-arpa:-1218300:uicsg:7600021:000:394 uicsg!mzp Apr 18 12:19:00 1984 [----------] Until the fancy UART interface chips came out (8251, etc.), they were just glorified parallel to serial (serial to parallel) converters, generally one of each on the chip with two parallel ports and two serial ports. You might try looking up some of the older UART parts (1602, AY-5-1013, or whatever), and seeing how they look. Mark Papamarcos ihnp4!uiucdcs!uicsg!mzp