rb@houxn.UUCP (R.BOTWIN) (08/25/83)
In case others are interested, I'm posting the centronix parallel interface pin descriptions: (note these are as used with Atari 800 via 850 interface unit --- which uses DB-15 connector...Also for EPSON printers use Amphenol 57-30360 ------36 pin connector). Desc 850/Comp Epson pin # pin # -STROBE 1 1 Data bits 1-8 2-8,15 20-27 -Ack N/A 10 BUSY 13 11 PAPER EMPTY N/A 12 SELECT N/A 13 -AUTO LINE FEED N/A 14 Logic Gnd 11 16 Chassis Gnd N/A 17 -INIT N/A 31 -ERROR (Also called -FAULT) 12 32 Logic Pull up (+5v) ***DO NOT CONNECT THIS! 10 35 VOLTAGE IS FOR SWITCHING NOT FOR CONNECTION This should allow others who use this standard to also hook up similar equipment (I hope). Source is 850 Interface manual and Epson printer manual. Rob Botwin ...houxn!rb ATTIS (201) 949-2039
kline@uiucuxc.UUCP (09/02/83)
#R:houxn:-40000:uiucuxc:3700064:000:641
uiucuxc!kline Sep 1 09:42:00 1983
Regarding this Centronics parallel discussion, can anyone
mail me the handshaking scheme on the STROBE L and ACK L lines?
It appears to be full-interlock, but I have no documentation
to explain.
Also, the BUSY and SELECT lines seem to have the same
function: in my (bad) documentation, BUSY is "high when data
cannot be received" and SELECT is "high when printer is
ready to receive data." I take it that when either of these
lines is high, the printer will ignore (not ACK) a byte
strobed to it.
Can anyone elucidate? Thanks!
Charley Kline, U of I CSO.
{pur-ee,ihnp4}!uiucdcs!uiucuxc!kline (Usenet)
KLINE@UIUCVMD (BITnet)brian@sdcsvax.UUCP (Brian Kantor) (09/03/83)
The "Centronics Standard Interface" refers to the connector and signals
sent to the printer and expected from the printer; in the case of the
connector it specifies only the PRINTER end of the cable, and not the
computer end of the printer cable.
The printer cable is expected to be 12 pair cable, each pair twisted,
and can be shielded overall to reduce interference with radio/tv.
The connector on the printer end is an Amphenol #57-40360 36pin male
connector with hood.
The signals and pinouts are as follows:
Signal Ground
pin pin Signal name Remarks
------ ------ -------------- -----------------------
1 19 Data Strobe/ paired with ground
2 20 data bit 0 ditto
3 21 data bit 1 ditto
4 22 data bit 2 ditto
5 23 data bit 3 ditto
6 24 data bit 4 ditto
7 25 data bit 5 ditto
8 26 data bit 6 ditto
9 27 data bit 7 ditto
10 28 Acknowledge/ ditto
11 29 Busy ditto
12 Paper Out paired with 13
13 Printer On Line paired with 12
17 Chassis Ground (cable shield)
How it works:
(All signals are TTL levels; high refers to ttl high output voltage,
2.4 volts minimum; low is TTL low, less than .8 volt. Printer represents
one standard TTL load maximum.)
The data is placed on the parallel data lines pins 2 thru 9, then
at least 500 nS later, the STROBE/ line (normally high) is taken low
for at least .5 uS, and for no longer than 500 uS. 500nS later the data
may change if desired.
Within 2 uS the BUSY line will go high if the operation requested causes
the printer to become busy. After the printer completes whatever operation
was requested (printing, paper movement, etc) the BUSY line will return
to its low state.
A low pulse on the ACKNOWEDGE/ (normally high) line will then occur.
At this point the sequence can be started over again to send the next
character or command.
If the printer runs out of paper, or is taken off-line, the BUSY line
will go high, and the appropriate line (PAPER OUT or ON LINE) will
indicate the status. Most computer systems check these after the BUSY
line has been continuously high for 1 second or more, and print a
message telling the operator to correct the printer fault.
Taken from centronics document "Technical Manual for Model 101A Printer"
Appendix B, July 1975.
(A note: in many cases, the driving microcomputer is slow enough that
it is only necessary to check the BUSY line, and the ACK/ signal may be
ignored.)
--
Brian Kantor, UCSD. {philabs,ucbvax} !sdcsvax!brian
sdcsvax!brian@nosc