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hey! I also need an 8-bit ISA ethernet card!!

M

MattCarp

Experienced Member
Joined
Sep 5, 2003
Messages
279
Location
Atlanta, Georgia (USA)
I'm also looking for an 8-bit ISA ethernet card with a twisted pair port. It appears that strict 8-bit ISA ethernet cards were relatively uncommon.

I've created an ISA bus adapter for my PCjr. It works just fine for a hard disk adapter, and now that that's working, I'd like to put my PCjr on the network.

My problem is that this is only an 8-bit ISA bus and most of the ISA ethernet cards I've found are 16-bit ISA or 8/16-bit. The 8/16-bit cards usually don't offer the range of IRQ settings I'd need for the PCjr. Specifically, I need to be able to set the card to IRQ2.

The total hardware guide (http://www.embeddedlogic.com/TH99/) has a nice breakdown of network cards and lists a number of 8-bit cards (and their jumper settings).

Ideally, I've love to get a D-Link DE-100TP
 
Re: hey! I also need an 8-bit ISA ethernet card!!

MattCarp said:
I've created an ISA bus adapter for my PCjr. It works just fine for a hard disk adapter, and now that that's working, I'd like to put my PCjr on the network.
Click to expand...

Do you intend to market this in some way, or publish the plans for others to use? I'm sure there'd be some interest.

--T
 
PCjr ISA adapter

PCjr ISA adapter

Good question. In fact, I did do a small production run of this ISA bus adapter for the PCjr for some other PCjr enthusiasts.

It turns out that the PCjr has most all of the ISA signals, except a few interrupts that the PCjr re-mapped and the DMA signals (since the jr doesn't have DMA). So, any ISA hardware that doesn't require the missing IRQ or DMA signals has a good chance of working. So, the adapter is relatively simple.

My board had one problem that took me a year to figure out: the ribbon cable caused a lot of signal distortion due to crosstalk from all of the parallel wires. With a new cable that separates the signals with ground wires (to act as buffers for the noise), it works.

The adapter is a simple 3-slot isa backplane, completely passive. The cross connects of the signals are all done on the bankplane, but you could do that with just the cable - it'd be cheaper than making a custom printed circuit board. However, making the cable is definitely a tedious thing.

So, I am quite pleased to have a PCjr that can actually boot from a hard disk. Now, if I can just get ethernet running with a standard ISA ethernet card, I'll be thrilled!
 
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