Wow! Looks like there isn't much in the way of supporting the TIM upgrade on new designs. I've poured over the datasheet numerous times.
I see a V9958, the full compliment of 128KB DRAM, a counter, and the faster crystal. I thought I did read the pin spacing was changed to an odd .09" (and of course pin functions) to make it not "drop in" compatible which explains the daughter card.
Also, I have never seen a real-life picture of the SOB before. Read about it, but's about it.
In 1986 I wrote to Yamaha to ask for a evaluation sample of the 9938. They sent me the chip. The pin spacing, 1.778mm or 0.07" stumped me. How to put it into a perfboard? I had never made a PCB, only wire wrap and solder. I called the US electronics distributors and no one had the socket for it.
A helpful TI engineer heard of my difficulty. He brought me a big 64 pin 0.1" machined pin socket (TMS9900 style), and a piece of balsa wood. He wire wrapped 64 little wires onto the 9938 pins, glued it onto the balsa block, and left me to solder the wires to the socket holes. I hot glued two rows of wire wrap headers onto my perfboard, to create a socket for the 64 pin socket.
It almost worked, even. It passed read/write memory tests with a pair of 4464s. Unfortunately I didn't know enough about the external circuitry to make the picture stable.
I still have that 9938 beast in my parts box. Then I got a Geneve and just used that... Much love for that chip.
Edited by FarmerPotato, Tue May 22, 2018 10:28 AM.