They have the same number of pins. It's always 40 pins, regardless of the ATA standard. The only difference might be the presence of pin #19 (The pin that is usually missing to prevent the user from inserting the IDE cable upside down).
Originally Posted by ShadeTail
The reason why some disks cannot be connected to the Playstation 2 network adaptor is because the gap between the ATA interface connector and power connector is too large (Usually only Western Digital disks are affected).
Fortunately, the user can opt to modify the Network Adaptor to accommodate the disk, so the user has options.
I don't think that the layout and positioning of the interface connectors were ever standardized, so Sony probably only intended their disks to be used with the Playstation 2.
Last edited by SP193; 03-28-2012 at 11:39 PM.
Reason: Corrected grammar
Unmodified SCPH-77006 with SM 3.6
SCPH-39006 with M-chip modchip, SCPH-10281 NA and refurb Seagate 80GB HDD
SCPH-10000 v1.00 with SCPH-10190 PCMCIA NA and SCPH-20400 HDD unit