First post, by HwAoRrDk
Does anyone have, or can point me to, any kind of clear, definitive reference for dimensions of ISA cards?
In particular, the dimension between card edge connector and bracket outside face (i.e. the face that contacts the chassis). I am going mad trying to correlate several different sources that are sometimes slightly ambiguous, sometimes contradictory, and sometimes not in agreement with reality. 😠
My first port of call was the IBM PC 5150 Technical Reference, page 1-35, which provides the following diagram:
But that doesn't include the mounting bracket at all. 🙁 It also doesn't agree with any ISA cards I have in my possession, because it specifies a distance of 98.933mm from back of card edge connector to front edge of board, whereas nearly all my cards measure approx. 102.5mm.
My next call was the EISA Specification 3.1, figure 97, page 254, which has the following diagram for an 8-bit ISA card:
This appears to have the dimension I am looking for, but the scan (and/or original document) is too crappy and I can't tell whether the 106.17mm dimension is to the inner face of the bracket, outer face, or centre line. On my selection of physical cards, most are all about 1mm short of that on the outside face; only one matches. So maybe the inner face? But the drawing doesn't quite look like the line is aligned that way...
Next, I remembered seeing some drawings for ISA cards in the PCI specification. And, lo, PCI Bus Specification Revision 2.2, figure 5-8, page 160, has a drawing:
Although, it and its same-page companion drawing are for some mythical extended and keyed 5V and 3.3V variations of an ISA card that I'm not sure ever existed. Regardless, it actually specifies that its dimension is to the outer face of the bracket, but the other end of the dimension is in the centre of the key notch, which isn't quite the back edge of the regular 8-bit edge connector, so is of little use. 🙁
Finally, I also found this:
Some guy's project to make his own POST card, for which he compiled specifications from various sources into one drawing. While the back-of-edge-connector-to-bracket-outer-face dimension of 105.156mm roughly corresponds to all my cards measured, it doesn't correspond for front-of-edge-connector-to-board-edge to the IBM drawing, which he himself mentions as reference. 😕
I think generally what also isn't helping the problem is that card manufacturers all use slightly different thicknesses of metal bracket. The only official source to specify a bracket thickness is the PCI standard, which says in a note on figure 5-12 "Material: .034 thk (20 ga)".
Help me before I go crazy!
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA 🫨
(Edit: I've no idea why the first picture isn't showing up inline.)
