mistux
Site Admin
Joined: 25 Jun 2004
Posts: 1042
Location: South Bend, Indiana USA
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 Posted: Thu Jan 09, 2014 11:00 am Post subject: LPT Printer Port Info |
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Most PC-compatible systems in the 1980s and 1990s had one to three ports, with communication interfaces defined like this:
Logical parallel port 1: I/O port 0x3BC, IRQ 7 (usually in monochrome graphics adapters)
Logical parallel port 2: I/O port 0x378, IRQ 7 (dedicated IO cards or using a controller built into the mainboard)
Logical parallel port 3: I/O port 0x278, IRQ 5 (dedicated IO cards or using a controller built into the mainboard)
If no printer port is present at 0x3BC, the second port in the row (0x378) becomes logical parallel port 1 and 0x278 becomes logical parallel port 2 for the BIOS. Sometimes, printer ports are jumpered to share an interrupt despite having their own IO addresses (i.e. only one can be used interrupt-driven at a time). In some cases, the BIOS supports a fourth printer port as well, but the base address for it differs significantly between vendors. Since the reserved entry for a fourth logical printer port in the BIOS Data Area (BDA) is shared with other uses on PS/2 machines and with S3 compatible graphics cards, it typically requires special drivers in most environments.
Source: http://en.wikipedia.org/wiki/Parallel_port
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Voltage should be 5v, some newer ones are only 3 volts. |
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