So, I'm new here, so here is a 'practice' post about something simple you folks have mentioned in this thread a few times. I've had good success with ISA slots, so I'm going to try to describe how I do so in the same way I'm going to describe other, hopefully more useful, topics.
An ISA connector works well, though a spacer is needed. For home-brew solutions to this problem they are readily available, and cutting a spacer out of a piece of scrap board is no big deal. Now, fer bulk production, that spacer is a pain - it wants to be a hair thinner than 1/16", (the mylar membrane is doubled at the connector with carbon over the trace as well.)
I just hacked (hacksaw) an edge connector off an old ISA board, then cleaned it up with a file, testing it repeatedly while thinning it (also with a file) until it went, but still giving a decent firm hold.
While still at the debugging prototyping stage, the ISA card can be stuffed into some wire-wrap pin strip, then stuck into a breadboard, or an old IDE cable etc...
Ugh, this is me first post - but pics are warranted. I din' get shots of the original filing down, but it should be clear what I did. I love filing, and will idly do it the way other folks might whittle or watch tv. I think this is straightforward, though... the tolerances are loose, and the bits flexible enough to handle moderate clumsiness:
So - that little whitish toothed spacer is also quite helpful - I found it stuffed into an old AGP slot, but you can make one out of anything. The key thing is that it spaces the two membrane connectors apart the correct amount so that they both will line up with the contacts of the ISA slot. Yes, I used a file to make it. The hook is just so you can get it out again, should you want to.
Now, you can see that I scraped the thickness of the scrap board down a bit. It only required about 0.1 mm, i.e. 1/10th of a mm. But - it really needs it: you don't want yer membrane folding and buckling as you try to force it in.
and here we have two easy ways to connect the back end of an ISA slot to yer prototyping environment, we have it easy here since we are only worried about one side of the pins so this will plug into a solderless breadboard at the other end without thought.
One side, half of an old chip-holder, for those who prefer their magic smoke kept inside chips. I soldered some normal straight pin-headers (e.g. fer jumpers, etc...) onto it, so I could use whatever ribbon cable I had handy.
In the other, the wire-wrap headers. both work well, though, with lots of headers you can stuff the ISA slot right into a breadboard and it will hold well. normally, that would suck, but again, we are only using one side at a time so we don't mind shorting across the ISA pins what are directly opposite.
Cool - images din' take too much damage from the 'resizing' process.
Oh, and I made it as stiff as I could get away with, while still being able to get it in. I put both pieces of membrane in using the white spacer to position them, then work the piece of card in which locks them in place. locks is about right - my cat knocked my setup off my desk, and my actual breadboard and a nasty 1394100 keyboard assembly (metal, membranes, keysockets, keys) all ended up dangling on either side of the back support of my chair - hanging by the bloody IDE connectors I was using.
Breadboard: I screw solderless breadboards, etc... onto it. I can't help it, it's the way I worked when I was a kid. Breadboards are made of wood, keyboards are made of IBM.
Anyway, to introduce myself, I'm working on a gaming mod fer 101 and 122 key IBM Model M keyboards.
The first step is documenting modifying the things to be USB keyboards without dropping simultaneous keypresses. Towards this end I've been working on a ps2 signal->USB converter that can handle either 101 or 122 key M's without promulgating that BS 'max 6 keys plus modifiers' tripe. That only applies to keyboards in boot mode - neither linux nor macs, nor 'dose forces that fer HID devices, the HID USB spec even describes how keyboards are supposed to implement their descriptors once a USB aware OS is booted. /endgripe
The next part, however is dealing with the ghosting inherent to matrix keyboards... much pain here resides. Thus I am currently hacking around with replacing bottom matrices, trying to read resistances to better than 1% while retaining the original matrix, etc...
'Yeah, I'll release my code under an open license, but... it's not cleaned up yet' (how many times have we heard that one before?)
So, I've used a number of the ideas from this site, so I think this is where I'll hang out and feed back my smaller tricks/ideas back into the community.
Wish me luck.
dfj
