It's looking like I'm going to at least build 3 of the boards I layed out above. DorkbotPDX takes in hobbyist board designs until they have enough for a full route and retain panel, then order 3 at a time. It's $10 per square inch for 4 layer boards for three copies. So that's only $10 a piece for three of the above. I probably won't make tomorrows order deadline, but hopefully soon after. I'll see how things work.
I had to correct an error in the schematic above for an alternate stuffing for maximum mode operation (doesn't apply to Jr).
Internal 512k expansion?
Re: Internal 512k expansion?
Last edited by alanh on Sun Jun 05, 2011 12:03 am, edited 1 time in total.
Re: Internal 512k expansion?
Oh, awesome. 
Let me know how it works out - I'm very interested in seeing this work.
Let me know how it works out - I'm very interested in seeing this work.
Re: Internal 512k expansion?
Well the boards came in and I already had the parts to stuff all three. Except I hit a bit of a show stopper snag. I'm a wire-wrap noob and didn't realize the pin diameter is about 3 times the pin size of a normal socket. So A) my plated holes on my PCB are too small, and b) the wire wrap pin tails are way to big to fit into the IBM stock cpu socket on the motherboard, and c) they are probably even too big to replace the existing motherboard socket with the wire wrap one.
The only way I think this will work is if I permanently solder the cpu on top of my board and let the solder drain down the hole with generous flux to the wire wrap socket placed flush against the underside; so that it all fuses together. Then clip the wire wrap pins really short. Then replace the MB wire wrap socket with a 40 pin dip socket I can get at Fry's that has very flexible v-wedge pin receptacles. But once I do all that, there's just no way I'm going to reverse it.
I ordered some surplus 8088-2s off eBay so I can try to attempt this when they come in. I just don't want to really screw up my Jr since I still plan on sending out IDE sidecar PCB orders this weekend and I need a working test bed when they come it. I'm just really curious if these boards will work.
The only way I think this will work is if I permanently solder the cpu on top of my board and let the solder drain down the hole with generous flux to the wire wrap socket placed flush against the underside; so that it all fuses together. Then clip the wire wrap pins really short. Then replace the MB wire wrap socket with a 40 pin dip socket I can get at Fry's that has very flexible v-wedge pin receptacles. But once I do all that, there's just no way I'm going to reverse it.
I ordered some surplus 8088-2s off eBay so I can try to attempt this when they come in. I just don't want to really screw up my Jr since I still plan on sending out IDE sidecar PCB orders this weekend and I need a working test bed when they come it. I'm just really curious if these boards will work.
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Re: Internal 512k expansion?
File down the pins!
I had to file down all the pins on my wire-wrap socket. Worked pretty well, for me, even only filing down the outsides of the pins.
I had to file down all the pins on my wire-wrap socket. Worked pretty well, for me, even only filing down the outsides of the pins.