Welcome to the Old Computer Troubleshooting Page

[cscott]

Hey,

I haven't worked on an old computer in ages and I'm not sure if anything was around before PATA... I'm asking this because I see no PATA ports. All the ports with the right "size" have one extra pin. Do I just have bad cables?

 

[cscott]

I realize now it says "IDE" written on the mobo beside these two ports. Why is there an extra pin (ie. 40 total)?

 

[cscott]

Guess I just needed 40 pin cables :)

 

[rcgldr]

PATA is a 40 pin connector. One of the pins near the middle isn't required, so it can be removed so that a 40 socket connector can have one of the sockets filled so that the connector only goes on one way.

Before PATA, hard drives were mechanisms similar to floppy drives. All of the memory for buffering was located on a controller card. Western Digital's ISA bus WD1003 hard drive controller was a popular controller. It could support two hard drives, and is the basis for the PATA interface.

A pair of PATA IDE hard drive on the same PATA cable emulate the WD1003 controller. A subset of the ISA bus goes out to both drives. Writing to ports updates the ports to both drives, but the currently selected unit is the only one that will respond to a command written to the command port. The idea was that IDE drives would be software compatable with the WD1003 controller.

Prior to PCs, controllers for hard drives were SCSI or proprietary.