serial port : Computer Hardware Buyers’ Glossary
- serial port
A connector to which you can connect a serial mouse, an external modem or a serial printer (not recommended!).
Modern computers aften have no serial ports, now that USB (Universal Serial Bus) has become so popular. On the computer the serial port
is a 9 or 25-pin D shaped male connector. There can be up to four COM (Component Object Model) ports. They
must be assigned the following way for all software to work. If they are improperly done, likely
some software will work. If there is an internal modem taking up com2: then there
must not be an external com2: port. Never assign com1:
and com3: without a com2:, or any other skip. Unfortunately,
there is only about a 1 in 3 chance your retailer will properly configure your COM ports.
It is possible to make serial ports work even if you don’t follow the standard pattern of IRQs (Interrupt Requests)
addresses, but life gets extremely complicated. There are then three different numbering schemes, the hardware
one, based on standard port assignments, which allows you to skip com3: and then have
com4:, the BIOS (Basic Input Output System) scheme that renumbers com4: to com3: if you skip com3:, and the Windows scheme on top of the BIOS scheme,
which allows com5: and above, and logical remapping of COM numbers to arbitrary physical
port addresses. Your software may use any one of the three numbering schemes. You must keep all three schemes in
sync, never skipping a port, always using the standard port addresses and IRQs
or you will create massive
||IRQ (Interrupt Request)|
The serial port is going the way of the dodo bird, replaced by the USB port which has smaller simpler cables
and the ability to double your ports using a splitter.