[GTALUG] computer hardware testing tools.

[Lennart Sorensen]

On Wed, Jul 12, 2023 at 06:18:41PM -0400, Karen Lewellen via talk wrote:
> no one spoke of printer cables.
> Serial connectors are 9 pin, parallel cables are 25 pin.  while old style
> printer cables use  25 pin as well, there is no, or not to my personal
> experience a 9 pin connector at all for those printer cables.
> as a side note allot of external speech synthesizer hardware used  25 pin
> connectors. and lpt port allocations as well.

Serial ports on PCs eventually tended to be 9 pin.  Earlier on and on
most other platforms they were 25 pin.  Usually the serial and parallel
ports used the opposite gender, but on some systems that was not the case.
Even worse, some systems (Macintosh and Amiga for example) even used 25
pin ports for SCSI (with the same gender as the parallel port, sometimes
places right next to each other.  Mixing them up fried things).
There were too many standards made by too many people.  Many of them
conflicting with each other.

So the number of pins tells you nothing about what the port is
unfortunately.  Or at least not with much certainty.

If the device has a serial interface, it connects to a serial port on
the PC.  If the device has a parallel interface it connects to a parallel
port on the PC.  The cable might adjust the connector, but it does not
change the protocol, unless it is an active cable (like a USB to serial
or USB to parallel cable for example).

-- 
Len Sorensen