Getting Nibbles to run on a Tandy 1000A

I have not had a chance to finish up the prototype yet, I have spent the last week cleaning up an IBM XT clone and repairing an IBM AT (5170) for a local business. during my lunch breaks at work, I designed a simple PCB for a cleaner version of my conventional memory expansion card. a couple of PDFs of the board can be found below, but beware I still need to double check everything on them. On the PCB, I decided to rely on the SRAMs ability to go in to high impedance and omitted the 74LS245. 

the SRAM chip used is an AS7C4096A-12JCN in an SOJ-400 package while the other three chips (74LS08, 74LS32, and 74LS139) are all SOL.

http://content.thetechnickel.com/misc/tandy-1000a/expansion/conventional-only/pcb-pdf/512KiB-RAM-Expansion-bottom.pdf

http://content.thetechnickel.com/misc/tandy-1000a/expansion/conventional-only/pcb-pdf/512KiB-RAM-Expansion-combined.pdf

http://content.thetechnickel.com/misc/tandy-1000a/expansion/conventional-only/pcb-pdf/512KiB-RAM-Expansion-silkscreen.pdf

http://content.thetechnickel.com/misc/tandy-1000a/expansion/conventional-only/pcb-pdf/512KiB-RAM-Expansion-top.pdf

quick note: use these PDFs at your own risk, they still need to be double checked for errors (well, tripple checked as I already double checked them). 

I was able to get the two stacks of SRAM jumpered together for all address and control lines that are shared as well as connect the address lines (A0:17) for the SRAM to the card edge connector. Tonight I will connect the AND, ORs, demux, and bus transceiver up and finish wiring the SRAM stacks. This is going to be quite a mess. I really need to invest in some decent wire and stop using network cable. hehe

I started working on the prototype tonight, armed with a general idea of what I wanted (and that included not wanting to do 24 connections on 16 different chips), I started tacking two sets of 8 SRAM ICs together. once both sets were all tacked together, I went thru and soldered the other common pins together. After getting the two sets of SRAM together, I decided that I should hammed out the memory decoder/demux so I hammered out a quick schematic based on the memory map I had created earlier

tomorrow at some point, I will scavenge around to locate the 4 7400 series ICs that I need and start to assemble the board.