TMS1100 ROM bits


I decapped a TMS1100 MCU to figure out the ROM layout. I chose the MP3438A from the 1979 game Star Wars Electronic Battle Command since Kevtris has successfully dumped the ROM and there is a patent for the game which includes a (slightly different) ROM dump listing.

Thermal decapping with a blowtorch went extremely well. The die looked clean, with just a few spots. I put it in an ultrasonic cleaner with some alcohol, but forgot about it over dinner. After about 90 minutes of being in the alcohol, I pulled it out and looked at it under the 'scope and was upset to see that the top metal layer had oxidized from the water in the alcohol.

I figured that this meant that there wasn't a passivation layer, so it would be easy to remove the top metal layer. After taking a set of pics I put it in some warm HCl, but only about half the metal came off. Next I'll try a little HF and see if that helps.

Taking cues from the F8 PSU and the Sharp SM510 MCU, I guessed the bit layout within each byte correctly; a byte histogram of my file and Kevtris' file matched. It took me a little while longer to figure out the byte layout, though. Once I did, I compared my file to Kevtris' and found 32 1-bit errors, a 0.2% error rate. Once I clean off the rest of the metal, I bet I can fix those.

Here's a quickie composite from ICE, with a little geometry tune-up in PS.

Here's a close-up of the ROM array.

Here's an annotated close-up of the ROM array after an acid bath.

Kevtris had also successfully dumped Microvision Vegas Slots, so I was going to hold onto it to play around with dumping the TMS1100 electronically, but Paul Robson is doing a Microvision RetroChallenge, so I decapped Vegas Slots to get a visual ROM dump. Here's an overlay showing the 1 bits. The vertical lines are ground and the horizontal line seperates chapter 1 from chapter 2. When these are rearranged according to the key above, the results are the same as the ROM dump.

Here's a complete die shot of Vegas Slots.

Here's a quickie die shot of Blockbuster.

Here's a quickie die shot of Bowling.

Here's a quickie die shot of Pinball.

I programmed a PIC microcontroller with a TMS-1100 emulator.


TMS-1000 Patent

Kevtris TMS1000/1100 info and ROM dumps

game Patent

Dan Boris's Microvision info and schematics

Info about the game

TI calculator simulator


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