VOGONS


First post, by cryptowhale

User metadata
Rank Newbie
Rank
Newbie

So I have that classic Asus P3B-F, but unfortunately it has only one ISA slot. P3B-F boards with two ISA slots exist, but they are hard to find and, with all that retro-craze in the recent years, pretty pricey.

I’m pretty confident with soldering iron so I guess I could add the second slot, but the problem is I don’t know where to source the ISA connector. And for P3B-F it should be a special ISA connector with offset pins, because the space occupied by the second ISA slot is shared with one of the PCI slots.

IMG_1874.jpeg
Filename
IMG_1874.jpeg
File size
1.54 MiB
Views
1029 views
File license
Public domain

One of the options is to find more readily available motherboard with similar configuration (shared ISA/PCI slot space) and desolder ISA connector from this motherboard. But I don’t know any of such boards besides P3B-F and so here I am, asking for the help from the Vogons community.

Do you know other motherboards with similar configuration?

Or maybe there is a way to source NOS ISA connectors with offset pins?

Any advice is welcome!

Reply 1 of 13, by Horun

User metadata
Rank l33t++
Rank
l33t++

I think they used long lead ISA sockets and bent those 10 to fit in those holes. Look for ones designed for wire wrap, they have .5"+ long leads and you should be able to bend them 90' then about 1/8" in bend again 90' to work.... just my opinion.

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 2 of 13, by zwrr

User metadata
Rank Newbie
Rank
Newbie

What is your purpose in adding a second ISA slot?
If in order to use multiple ISA devices, why not try this.
Short on ISA slots? Try this.

486DLC-40, 386-VC-H, 32MB, GD5429, ES1868F


X5-133, HIPPO-15, 32MB, Riva 128, ES1868F


5x86-120GP, SYL8884, 32MB, Trio64V+, ES1868F


Pentium MMX-233, T2P4, 128MB, TNT2, SB16


Tualatin-1.4G, 694X, 512MB, G400, Voodoo2, SB AWE32

Reply 3 of 13, by cryptowhale

User metadata
Rank Newbie
Rank
Newbie

Thanks for the link, but I’ve already read this (and related) threads. The purpose is to have two ISA soundcards in the system and not just for testing. So the ISA riser/backplane solution is not so convenient for me because it will require case modification and limit case selection. I’m considering it as a last resort option.

Last edited by cryptowhale on 2024-01-10, 07:02. Edited 1 time in total.

Reply 4 of 13, by cryptowhale

User metadata
Rank Newbie
Rank
Newbie
Horun wrote on 2024-01-10, 03:30:

I think they used long lead ISA sockets and bent those 10 to fit in those holes. Look for ones designed for wire wrap, they have .5"+ long leads and you should be able to bend them 90' then about 1/8" in bend again 90' to work.... just my opinion.

It’s an interesting idea! But where to source these wire wrap ISA connectors? I can’t just rip them off from some spare motherboard because the leads will be already shortened.

Reply 5 of 13, by cryptowhale

User metadata
Rank Newbie
Rank
Newbie

Never mind, I’ve found wire wrap ISA connectors on the Digikey. Unfortunately, judging by the connector blueprint, the connector has very limited space underneath it - if I want to make a 90 degree bend, the bend curvature radius should be minimal for the bent lead to fit under the connector (I.e. fit in the way that connector height won’t increase) and with such a small radius the lead could simply break.

Maybe someone from the community has two ISA slot P3B-F and could check if the second ISA connector really has bent pins underneath it?

Reply 7 of 13, by cryptowhale

User metadata
Rank Newbie
Rank
Newbie
Bancho wrote on 2024-01-10, 08:33:

I have a 2 Slot PB3-F. If i get chance i will try and get some pictures for you.

Thanks! BTW, judging from the Wikipedia photo, the second ISA connector slightly differs from the first connector in design. I think it was made by different manufacturer. And it has some markings on the side, but it’s difficult to read them in this photo.

Reply 9 of 13, by Bancho

User metadata
Rank Oldbie
Rank
Oldbie

I got some pics the evening. Its too hard to capture how the legs are, but the bottom row of legs on the isa slot go inward at an angle. Board is a V1.04.

drTFnDch.jpg
ruw7WIrh.jpg

I tried my best to get a pic that shows how the pin sits in the slot.

eL5vIG0h.jpg

Reply 10 of 13, by cryptowhale

User metadata
Rank Newbie
Rank
Newbie

Wow. So looks like they are really bent, though not at 90 degrees. And I think they are factory bent by the connector manufacturer - there was no point in using connector from different manufacturer if Asus could it themselves. Probably it’s a custom order but we’ll never know because EDA Inc. is long time defunct.

Well, I think the next step would be to buy a bunch of ISA connectors and try to bend the leads in the same way. And design a testbed PCB. And make a bending template.

Anyway, it should be a fun project. I’ll keep you posted but I’m a slowpoke (and have other work to do), so don’t expect any updates soon.

Bancho, thank you very much for the photos!

Reply 11 of 13, by janskjaer

User metadata
Rank Member
Rank
Member

I got your PM, and I've only just had a chance to get to the motherboards.

I've taken a couple of photos of the two-slot P3B-F. Hopefully, these can help

Attachments

DELL Dimension XPS M200s
:Intel P1 MMX 200MHz
:64MB EDO
:DOS 6.22/Win95b
:Matrox Millenium II + m3D (PowerVR PCX2)
Chaintech 7VJL Apogee
:AMD AthlonXP 2700+
:512MB DDR
:Win98SE/2000 SP4
:3dfx Voodoo5 5500 AGP