PC Bus Card Edge Connector Information:

The connector which a PC's expansion cards plug into is called a card edge
connector. Unfortunately, many manufacturers don't actually use familiar card
style names like "ISA" or "PCI" when describing their card edge connectors.
They use the connector's physical dimensions, requiring you to know these
dimensions if you want to get the kind of connector you're looking for. There
are two main specs which you need to know if you're looking for card edge
connectors. The first is the contact spacing, which means how far apart the
contacts on the connector are spaced.

ISA uses 0.100" (2.54mm) contact spacing.
PCI uses 0.050" (1.27mm) contact spacing.
AGP uses 0.039" (1mm) contact spacing.

The other spec you need to know is how many contacts the connector has.

8-bit ISA has 62 contacts.
16-bit ISA has 98 contacts.
PCI and AGP both have 124 contacts.

Irritatingly, even once you know the physical specifications for the card
edge connector you want, it's surprisingly difficult to find a place where
you can buy them. Because card edge connectors are not a consumer item, they
are typically only sold in large quantities to manufacturers. You may have a
difficult time finding the card edge connector you want if you simply call a
manufacturer and ask to buy one or two connectors; Most places will want you
to open an account with them, and proof that you're a valid reseller. If
you're lucky enough to find a reseller that distributes these parts to end
consumers, make a note of them.