XTIDE and 3com NICs \ VOGONS

XTIDE and 3com NICs

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First post, by sirlemonhead

Posted on 2016-08-04, 21:20

sirlemonhead Offline

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Hi guys,

I've got a 3com 509 ISA card with a 24 pin EPROM socket, with an XTIDE bios in it. Works great!

I happen to have a second XTIDE EEPROM and I'd like to do the same in another machine, but only seem to have later PCI 3com cards with 32pin sockets. The EEPROM is 24 Pin. The card is a 905 model

Can I put the 24 pin rom in the 32 pin socket? I tried it based on what I found online - I put the rom in such a way that the end of the socket with the notch on it is the end of the socket with the 8 empty pins when the socket is in. Is this correct?

I can get into the 3com config software and the EPROM is enabled, but no XTIDE interface appears on machine boot. I notice the bios offset is hard coded for something like 0xh and can't be changed - will this be a problem? I think the XTIDE needs to be at 0xc8 or something? Is there any way to change this outside of the 3com software perhaps?

Thanks!

Reply 1 of 8, by stamasd

Posted on 2016-08-05, 00:15

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The XTIDE BIOS needs to be mapped in the area that the motherboard BIOS scans at POST for extensions, typically 0xc8000 to 0xf7fff. It also needs to be aligned so that its signature (55AA IIRC) is right at the beginning of a 32kB boundary (c8000, d0000, d8000 etc)

If your NIC doesn't map the EPROM in this way, it won't work.

I/O, I/O,
It's off to disk I go,
With a bit and a byte
And a read and a write,
I/O, I/O

Reply 2 of 8, by BloodyCactus

Posted on 2016-08-05, 02:38

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a 24pin eeprom like a 27C16, 27C32 etc is not pin compatible with a 32pin 27C040 eeprom.

also, not all bios will scan the 0xF0000+ bios area for isa extensions, its not in the standards defined range for isa extensions.

--/\-[ Stu : Bloody Cactus :: [ https://bloodycactus.com :: http://kråketær.com ]-/\--

Reply 3 of 8, by stamasd

Posted on 2016-08-05, 02:44

stamasd Offline

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BloodyCactus wrote:
a 24pin eeprom like a 27C16, 27C32 etc is not pin compatible with a 32pin 27C040 eeprom.

It's not, but it can be made compatible with a little modification of the socket.

also, not all bios will scan the 0xF0000+ bios area for isa extensions, its not in the standards defined range for isa extensions.

The XT bios does - at least mine does.

I/O, I/O,
It's off to disk I go,
With a bit and a byte
And a read and a write,
I/O, I/O

Reply 4 of 8, by BloodyCactus

Posted on 2016-08-05, 02:56

BloodyCactus Offline

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stamasd wrote:
BloodyCactus wrote:
a 24pin eeprom like a 27C16, 27C32 etc is not pin compatible with a 32pin 27C040 eeprom.

It's not, but it can be made compatible with a little modification of the socket.

quite a few pins need re-routing. easier to just get a 27c40

stamasd wrote:

The XT bios does - at least mine does.

it might, but its non-standard. the xi8088 does, on purpose so you can have the xtide bios embedded in it specifically.

http://www.scs.stanford.edu/05au-cs240c/lab/specsbbs101.pdf

page 12.

3.4 Legacy IPL Devices
This is a standard ISA card with a valid option ROM that resides in system memory
address space between C0000h and EFFFFh on a 2k boundary.

--/\-[ Stu : Bloody Cactus :: [ https://bloodycactus.com :: http://kråketær.com ]-/\--

Reply 5 of 8, by stamasd

Posted on 2016-08-05, 13:03

stamasd Offline

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BloodyCactus wrote:
stamasd wrote:
BloodyCactus wrote:
a 24pin eeprom like a 27C16, 27C32 etc is not pin compatible with a 32pin 27C040 eeprom.

It's not, but it can be made compatible with a little modification of the socket.

quite a few pins need re-routing. easier to just get a 27c40

Actually no, just 1 pin. You place the 2716 at the end of the socket away from the notch, and run a wire from pin 32 to pin 28 of the socket (and unsolder/cut/insulate pin 28 from the PCB). That's all.

I/O, I/O,
It's off to disk I go,
With a bit and a byte
And a read and a write,
I/O, I/O

Reply 6 of 8, by h-a-l-9000

Posted on 2016-08-05, 16:47

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You cannot run an ISA option ROM in a PCI card. The system PCI BIOS looks for a signature that contains the PCI device ID of the card. If it doesn't match, the ROM is ignored.

1+1=10

Reply 7 of 8, by sirlemonhead

Posted on 2016-08-16, 18:07

sirlemonhead Offline

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Thanks guys, I'll abandon this idea.

I guess I'll grab another ISA 3com card... though they seem to have really high postage costs on ebay.co.uk unfortunately 🙁

Reply 8 of 8, by carlostex

Posted on 2016-08-16, 22:43

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If you want to do it properly you could build this:
https://www.lo-tech.co.uk/wiki/ISA-ROM-Board

Unless you still want to use the networking functionality of a NIC card.

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