Roger's Cable Page


O2 Parallel Port:

Why does the parallel port look different than the Indy?

The O2 parallel port supports the new IEEE standard 1284C for parallel ports, including bidirectional I/O.

What are the pinouts on the parallel port?

O2 uses the standard IEEE 1284-C cable. The current Centronics 25-pin connector on host side is called IEEE 1284-A and 36-pin connector on printer side is called IEEE 1284-B. The O2 uses a 36-pin mini-connector called IEEE 1284-C which has different pin assignments than type A and type B. The type-C cable has been available for a while and should be available from most of the computer supply stores.

The IEEE 1284-C specification is described in IEEE Std 1284-1994 document "IEEE Standard Signaling Method for a Bidirectional Parallel Peripheral Interface for Personal Computers" page62-63. Customers requiring more details will need to order a copy of IEEE std 1284-1994 document or they can access FarPoint for some information.

Here is an IEEE 1284-C pin assigment in Compatible (Centronics) mode:

1284C Pin Signal Name Signal Description Centronics Pin
1 BUSY
2 SELECT
3 nACK
4 nFAULT
5 pERROR
6 DATA 1
7 DATA 2
8 DATA 3
9 DATA 4
10 DATA 5
11 DATA 6
12 DATA 7
13 DATA 8
14 nINIT
15 nSTROBE
16 nSELECTIN
17 nAUTOFEED
18 Peripheral logic HIGH
19 GND signal ground (BUSY)
20 GND signal ground (SELECT)
21 GND signal ground (nACK)
22 GND signal ground (nFAULT)
23 GND signal ground (pERROR)
24 GND signal ground (DATA 1)
25 GND signal ground (DATA 2)
26 GND signal ground (DATA 3)
27 GND signal ground (DATA 4)
28 GND signal ground (DATA 5)
29 GND signal ground (DATA 6)
30 GND signal ground (DATA 7)
31 GND signal ground (DATA 8)
32 GND signal ground (nINIT)
33 GND signal ground (nSTROBE)
34 GND signal ground (nSELECTIN)
35 GND signal ground (nAUTOFEED)
36 Peripheral logic HIGH