PARALLEL Port (LPTx)

PARALLEL Port (LPTx) (default IRQ-7)

See > IEEE 1284-1994 - Parallel Port Standards

The Cable-length should not exceed 1.85 meters (6 feet), because the signals are directly driven by TTL-circuits (74LS473 Latch) at a high-speed rate.

However - cables up to 4-meters in length may work, on another machine a 2.5-meter cable may produce errors !
Use only a approved, High Quality cable for the parallel port !

25-Pin CPU / 36-Pin Printer Cable Layout (DB-25 to Centronics)
(IN/OUT signal shown from CPU-Side 25-Pin female connector)

CPU	PRN	Signal Name	dir	-	CPU	PRN	Signal Name	dir
1	1	-Strobe (-WRITE)	OUT		14	14	-Auto Feed XT (-DSTRB)	OUT
2	2	Data Bit 0	I/O		15	32	-Error	IN
3	3	Data Bit 1	I/O		16	31	-Init Printer	OUT
4	4	Data Bit 2	I/O		17	36	-Select Input (-ASTRB)	OUT
5	5	Data Bit 3	I/O		18	*)	Ground
6	6	Data Bit 4	I/O		19	*)	Ground
7	7	Data Bit 5	I/O		20	*)	Ground
8	8	Data Bit 6	I/O		21	*)	Ground
9	9	Data Bit 7	I/O		22	*)	Ground
10	10	-Acknowledge	IN		23	33	Shield GND
11	11	Busy (-WAIT)	IN		24	*)	Ground
12	12	Paper End (empty)	IN		25	*)	Ground
13	13	Select	IN

NOTE: PINs marked with *) are SIGNAL-GROUND
On DB25-side Pin 18 to 25 (except Pin-23) are Ground.
On Centronic-side Pin-19 to 30 are SIGNAL-GROUND, Pin-33 is Cable-Shield.

Standard (SSP), Bidirectional, ECP, EPP and ECP/EPP - Modes

•  Standard This AT-compatible mode (SSP) is the default mode. In this mode, the
   parallel port is limited to writing information to the device attached to it.
   This mode can be used with most IBM-compatible parallel printers.
•  Bidirectional This PS/2-compatible mode is a bidirectional mode used for
   data transfer to other PC systems and supported devices.
•  ECP The enhanced capabilities port (ECP) mode is a high-performance , bidirectional
   mode that uses direct memory access (DMA) for data transfer to a high-speed printer or other devices.
   The extended mode makes the parallel port an 8-Bit parallel Bi-directional interface and
   makes DMA available for Type 2 and Type 3 controllers. The parallel port provides half
   duplex transfers when in bidirectional operation mode. Direction is determined by the device control
   register and DMA is controlled trough the Interface Control Register.
•  EPP This enhanced parallel port (EPP) mode is a high-performance, bidirectional mode
   that has capabilities similar to ECP mode, the main difference is that EPP data transfers are
   processor-initiated instead of DMA, EPP supports the connection of up to eight external devices such
   as hard disk drives, CD-ROM drives, tape drives, diskette drives and a printer to the parallel port.
   These devices can be connected to each other in a daisy-chain  arrangement, or they can be connected
   through an external multiplexor. The attachment of multiple devices requires device drivers supplied by the
   device manufacturers.
•  ECP/EPP This mode combines the capabilities of the ECP and EPP modes.
   Select this mode to connect both ECP and EPP devices to the parallel port.
   (ECP/EPP mode need special drivers as avail. in Microsoft Windows)

Type 2 and Type 3 controllers
The TYPE-2 controller is fixed arbitration level 6 and the TYPE-3 controller allows arbitration levels to be configured to any level.

ValuePoint.	Parallel Port Type.
VP-I	TYPE-1
VP-Si	TYPE-1
VP-II	TYPE-2 (PC ID block Dongle not supported)
VP-P60/D	TYPE-3
VP Performance Series	TYPE-3

Address Assignments TYPE-1
(Parallel 1 same assignment as PC-XT LPT1: Display/Printer Adapter)

Port	Data	Status	Control	Reserved
Parallel 1	03BC	03BD	03BE	03BF
Parallel 2	0378	0379	037A	037B
Parallel 3	0278	0279	027A	027B

Address Assignments TYPE-2

Port	Data	Status	Control	Reserved	I/F Control	I/F Status
Parallel 1 NO DMA support	03BC	03BD	03BE	03BF
Parallel 2	0378	0379	037A	037B	037C	037D
Parallel 3	0278	0279	027A	027B	027C	027D

Address Assignments TYPE-3

Port	Data	Status	Control	Reserved	I/F Control	I/F Status
Parallel 1 to use full function use next at H1278	03BC	03BD	03BE	03BF
Parallel 1	1278	1279	127A	127B	127C	127D
Parallel 2	0378	0379	037A	037B	037C	037D
Parallel 3	0278	0279	027A	027B	027C	027D
Parallel 4	1378	1379	137A	137B	137C	137D

When using TYPE-3 parallel port 1 in compatibility mode, set the arbitration level to disable.

Parallel (25-Pin) LAPLINK Cable (C) Traveling Software, Inc.

   COMPUTER-A     COMPUTER-B
      PIN            PIN
       2     ----     15      (D0)
       3     ----     13      (D1)
       4     ----     12      (D2)
       5     ----     10      (D3)
       6     ----     11      (D4)
      10     ----      5
      11     ----      6
      12     ----      4
      13     ----      3
      15     ----      2
      25     ----     25
   18 to 24  ----  18 to 24   (SG)
PINs 18 to 24 are Signal Ground, they should be connected/twistet with PIN 2 to PIN 6 on each cable-side (signal-shield).

See > IEEE 1284-1994 Parallel Port Standards

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