I have recently posted about getting a Tandy 286 Express Accelerator and putting in my Tandy 1000A (Model 25-1002) just a short while ago:

Tandy 1000A (25-1002) w/PC Technologies 286 Express Accelerator Card

I have also written previously on my attempt to recreate a Tandy 1000 SX with a Tandy 286 Express Accelerator and how that did not work out the way I planned:

Recreating the Tandy 1000 SX I had over 30 years ago

The urge was just too strong to put that Tandy 286 Express Accelerator in my Tandy 1000 SX instead of the Tandy 1000A, so that is exactly what I did, but then I started having lockup problems. Now I know the accelerator works, because I had it running in my Tandy 1000A computer with no issues. My first suspect was memory. The computer came with 640K so I did not even give the memory a 2nd thought when it was running without the accelerator, but I took a closer look and then discovered whoever upgraded this Tandy 1000 SX had used a mixture of different 256Kx1 dram chips with various speed ratings. I had a few issues previously with the Tandy 1000 SX with an NEC V20 CPU, but I guess putting in a 286 accelerator pushed the memory too hard. I ordered a completed memory replacement of 100ns memory consisting of 4 64kx4 and 16 256kx1 dram chips. 100ns memory is probably over kill, but at $1 per chip I wasn't going to argue with that. I sprayed each dram socket with DeoxIT and swapped out the memory. I am pleased to say that I have no more lockup issues and the computer is working as expected.

This Tandy 1000 SX is different than my old one because that one never had a XT-IDE with Compact Flash storage, upper memory or an EMS board, such is progress. In the final analysis, I did recreate my computer from 30+ years ago and that is all that matters to me.