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Funnily enough that was pretty much my initial idea, but I don't know if the signal trace length would be a issue I'm taking the approach of making a breakout SIMM that has connectors that can be plugged into either a RAM card or a riser module as this allows for flexibility of exactly what is...

This is one of the approaches I'm looking in to, just as long as there is actually space somewhere in the LC III to stuff the other simm slot

Normally the LCIII is limited to 36MB of RAM - 4MB onboard and one 32MB SIMM The simms are limited to 32MB as there are only 11 address lines hooked up to the RAM SIMM socked so larger sticks won't work (The will typically show up as 16 or 32MB) However while creating a pin listing for the...

I have some memory related shenanigans going on with the LC III at the moment, if what I'm planning works it's going to be really cool :)

Yep :) applying something between about 7v and 20v on VPP just before VCC goes high will often bypass the lock bit on GAL's. The exact voltage and timings vary between chips In theory this can be done manually with something like a TL866 and a bench power supply (I believe @Bolle dose it this...

Oh and as a bit of a aside I noticed U47 on my board was a GAL16V8 and since I needed to desolder it for cleaning I figured I might as well throw it into my Galdurino and see if it was crackable, and it was! 9V on VPP got the chip to divulge it's contents Attached is the JED and Equation file...

Quite a few years ago I got my hands on a Quadra 840av for a very reasonable price (£20) I wasn't really looking for a Q840 and tried to avoid buying it, but no one else at the sale I got it from seemed interested in it and given it's very reasonable price I couldn't resist it in the end! That...

Turning this mess (back) into a PCB looks like fun...

More multicolour spaghetti!

Pinout is different between the 5380 and 53C80 so it's not a straight swap. I just ordered one though and might try and rats-nest it onto the repro IIcx board and see what happens

Very nice! The no video issue is likely just bad solder joints, usually on the analog to logicboard connector, yolk connector or flyback (or all of the above!) I wouldn't even bother inspecting the joints at this point, just suck all the solder off them and put fresh on. Only start more in...

All in good time, gotta finish that half finished LC III schematic first :) Which reminds me I still need to send you that scaled down IIcx trace layout.... I'll remember to do it one of these days!

Much progress has been made since my last post! The board was (almost) fully assembled ready for testing at the weekend: (and yes, that board is totally coated in flux so every little bit of crud on my desk sticks to it which is lovely..... this board really needs some quality time in the...

There should also be a dot on the logicboard on one side of the FPU slot to denote pin 1 of the slot, this corresponds with a dot engraved on one side of the FPU denoting pin 1 of the chip Even though it looks like it should be possible you shouldn't actually be able to insert the FPU in the...

27C400 should be correct for the CC ISTR you need to byteswap the image before programming it, but it's been a while since I have done it so I might be wrong there..... If you have at leas tone working ROM chip you can just dump it as a 27C400 to find out

Thanks :) Nope, just forgot to remove it :)

Annnd 17 days later: This thing is going to take ages to assemble.... And it just occurred to me I forgot to order the axial 'lytics.... Hopefully I have radials in the appropriate values

Corrected a issue with OE on the RAM page not being connected to anything (it should have been grounded on all chips), Changed the symbol for the 78L08 at UA10 to show all connected ground pins as well as some other minor component labelling changes

Fair enough! If they are the chips I think they are i'm impressed you found them at all (I tried and couldn't. Ended up pulling them from 72pin simms given to me by a 68kmla member)