The parallel port has been introduced to control a printer. Since printers are output devices there where 8 outputs to pass an ASCII character to the printer and some inputs to get the status back. The parallel port got quickly used for other things and got expanded, therefore the following version can appear. Some BIOS allow to choose between them
Type |
Date of Introduction |
Bidirectional |
DMA
|
Speed |
Standard parallel port (Standard Parallel Port SPP) |
1981 |
No |
No |
150 Kbyte/sec
|
Parallel port PS/2 (bidirectional) |
1987 |
If |
No |
150 Kbytes/sec |
Enhanced Parallel Port (EPP) |
1994 |
If |
No |
2 Mbytes/sec |
Extended Capability Port (ECP) |
1994 |
If |
If |
2 Mbytes/sec |
To use the the parallel port to control some custom hardware as LCDproc make sure DMA is disabled.
The Pinout of the parallel Port:
Pin |
Name |
Dir |
1 |
Data Strobe |
out |
2 to 9 |
Data 0 to 7 |
out /(and in) |
10 |
Acknowledge |
in |
11 |
Busy |
in |
12 |
Paper Out |
in |
13 |
Select |
in |
14 |
Autofeed |
out |
15 |
Error |
in |
16 |
Reset |
out |
17 |
Selected |
out |
18 to 25 |
Ground |