Parallel Ports - An introduction to parallel port technology
Credit for this information should go to Mark Clarkson (who says he hates
parallel ports).
The parallel port on your PC today is a 1981 design, which runs at up to
150 Kb/sec. The maximum cable length is about 3 m.
IEEE standard 1284 defines a newer, faster, and better parallel port, which
will run at up to 4 Mb/sec. The good news is 1284 ports are
backward-compatible with existing parallel ports. Even better news is that,
for only the cost of a new cable, a 1284 parallel port can inject new life
into your old printers. The maximum cable length will be about 10 m. Cables
as well as ports are covered by the new standard.
1284 ports come in 4 flavours.
Multiple
Name or peripherals Major
Acronym Full name Bidirectional? per port? usages
------- --------- -------------- ----------- ------
nibble Yes
byte Yes
ECP Enhanced Yes host-to-
Capabilites printer
Port
EPP Enhanced Yes Yes CD-ROMs,
Parallel hard disks
Port
This simply means a 1284-compliant peripheral can talk to the host, eg to
inform the host of its (the peripheral's) capabilities.
See my articles ``Serial Ports'' and ``SCSI Technology''.
'Pumping Up the Parallel Port', Byte, August 1994, p 118, by Mark Clarkson.
This article was written by Ron Savage in 1997.
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