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Discussion Overview

The discussion revolves around troubleshooting and understanding the connections and specifications of old computer hardware, specifically focusing on the PATA (Parallel ATA) interface and its historical context. Participants explore the characteristics of IDE ports and cables, as well as the evolution of hard drive controllers.

Discussion Character

  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant questions the absence of PATA ports and suggests the possibility of having bad cables.
  • Another participant notes the presence of "IDE" labeling on the motherboard and inquires about the significance of an extra pin in the connector.
  • A later reply confirms the need for 40-pin cables for the connection.
  • One participant explains that PATA connectors have a 40-pin configuration, with one pin being unnecessary for proper connection, allowing for a keyed design.
  • The historical context of hard drives is discussed, mentioning that before PATA, hard drives operated similarly to floppy drives and were managed by a controller card, specifically referencing the Western Digital ISA bus WD1003 controller.
  • It is mentioned that PATA IDE hard drives emulate the WD1003 controller, with a specific communication method for addressing multiple drives on the same cable.
  • Prior to the advent of PCs, hard drive controllers were typically SCSI or proprietary.

Areas of Agreement / Disagreement

Participants present various insights and historical information, but there is no clear consensus on the initial issue regarding the absence of PATA ports or the implications of the extra pin. The discussion remains exploratory with multiple viewpoints expressed.

Contextual Notes

Some assumptions about the hardware's condition and compatibility are not fully explored, and the discussion does not resolve the initial question about the absence of PATA ports.

cscott
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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?
 
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I realize now it says "IDE" written on the mobo beside these two ports. Why is there an extra pin (ie. 40 total)?
 
Last edited:
Guess I just needed 40 pin cables :)
 
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.
 

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