JP 500  (260-2950)               Pinouts               Faxback Doc. # 3645

Printer Interface

Host Clk/(nSTROBE)               01         ->
         DATA BIT          0     02         ->
         DATA BIT          1     03         ->
         DATA BIT          2     04         ->
         DATA BIT          3     05         ->
         DATA BIT          4     06         ->
         DATA BIT          5     07         ->
         DATA BIT          6     06         ->
         DATA BIT          7     09         ->
PtrClk/(nACK)                    10         <-
PtrBusy/(BUSY)     s              11         <-
AckDataReq/(PERROR)              12         <-
XFlag/(SELECT/ONLINE)            13         <-
HostBusy/(nAUTOFD)               14         ->
NC                               15
LOGIC GROUND                     16
CHASSIS GROUND                   17
NC                               18
                                 19 SIGNAL GROUND/(Ret Pin 1)
                                 20 SIGNAL GROUND/(Ret Pin 2)
                                 21 SIGNAL GROUND/(Ret Pin 3)
                                 22 SIGNAL GROUND/(Ret Pin 4)
                                 23 SIGNAL GROUND/(Ret Pin 5)
                                 24 SIGNAL GROUND/(Ret Pin 6)
                                 25 SIGNAL GROUND/(Ret Pin 7)
                                 26 SIGNAL GROUND/(Ret Pin 8)
                                 27 SIGNAL GROUND/(Ret Pin 9)
                                 28        GROUND/(Ret Pins 10, 12, 13)
                                 29        GROUND/(Ret Pins 11, 32)
                                 30        GROUND/(Ret Pins 14, 31, 36)
                                 31 nINIT
                                 32 nDataAvail/(nFAULT)
                                 33 LOGIC  GROUND
                                 34 NC
                                 35 NC
                                 36 1284 Active/(nSELECTIN)

Connector Pins and Corresponding Signals

PIN      SIGNAL                  SIGNAL DESCRIPTION
       DIRECTION

1      to printer                nSTROBE (HostClk)

                                 Signal, valid at logic level 0, used to
                                 transfer data to the printer.

2-9    to printer                DATA BIT 0 - 7
                                 Data transmission bus.

Data 7 is the most significant bit.

10     from printer              nACK (PtrClk)

                                 Set at 0 and then at 1 to request
                                 a data byte from host.

11     from printer              BUSY (PrtBusy)

                                 Set at 1 to indicate that the printer is
                                 not ready to receive data.

12     from printer              PERROR (AckDataReq)

                                 Set at 1 to indicate that the printer
                                 is out of paper.

13     from printer              ON LINE (Xflag)

                                 Set at 1 to indicate that the printer is
                                 ON LINE.

                                 This signal is also handled using command
                                 code ESC Q (printer deselection).

14     to printer                nAUTOFD (HostBusy)

                                 When set at 0, indicates that a CR is
                                 added to each LF received.

16     ---                       LOGIC GROUND

                                 Logic ground level (O V).

17     ---                       FRAME GROUND

                                 (Printer earthed through host).

19-30  ---                       SIGNAL GROUND

                                 Twisted pair return lines.

31     to printer                nINIT.

                                 Hardware printer reset.

32     from printer              nFAULT (nDataAvail.)

                                 Set at 0 when the printer OFF LINE or an
                                 error has occurred.

33     ---                       LOGIC GROUND

                                 Logic ground level (O V).

36     to printer                nSELCTIN

                                 Set low by host to select printer.

                                 Command codes DC1/DC3 are handled only
                                 when the signal is at level 1.

Slow Down Mode

To avoid "time-out" problems with MS-DOS operating systems, the printer
automatically reduces the reception speed when the line buffer is almost
full.  In this situation, the printer accepts only one character every two
seconds from the line, thus guaranteeing that there will be no reception
interruption for time-out.  Once the data has been unloaded by a print
operation, the reception speed will return to its normal value.

(br/all-12/13/94)