Top Gun LCD game

Top Gun is a 1989 LCD game from Konami. It used a Sharp SM510 MCU

The Patent has lots of technical info, including full schematics and a ROM dump! I used the ROM dump to figure out the layout of the bits in the ROM in the MCU.

The processor is "globbed" with epoxy. I dissolved it with Decap followed by sulfuric acid. Here are some pics:

front of PCB

back of PCB

rough pic of full die - major areas are RAM, LCD RAM and ROM

pic of ROM array

pic of ROM array after acid wash

high contrast pic of ROM array after acid wash

annotated pic of ROM array

close up of page 0/bit 7 showing byte locations in page

The ROM dump in the patent is a little different from what's on the die. The SM510 MCU has 44 pages of 64 bytes, but the patent shows 4096 bytes. The additional bytes are probably left over from some other game, maybe TMNT. The unused 64th byte in each page is 00 in the patent, but $80 on the die. Lastly, 2 bits are different on the die. The patent text is hard to read in places, but now I think those 2 bytes are the same.

ROM dump from patent, with unused pages set to 00 and 64th byte in each page set to $80

ROM dump from die


The schematic in the patent doesn't quite match the PCB: the buttons and LCD are connected differently.

      K1      K2      K3     K4
S1   left     up     down   right
S2  select   sound   off    fire
S3    on      --      --     --

Here's a diagram from the patent that shows the 9 areas on the LCD where enemy planes and missiles appear, and where you can move the gun sight.

upper left    upper center    upper right
middle left   middle center   middle right
lower left    lower center    lower right

The LCD segments are numbered in the diagram, but there are some issues: some explosions are shown as 2 different segments, but they are connected; some explosions are not numbered; the left gun is shown as segment 266, but it should be 268; segment 288 was skipped; score and damage are shown as one segment number, but have multiple segments; waves and clouds are numbered the same on the right and left, but are different segments; and the smallest cloud and wave are connected.

Here's the diagram without the segment numbers.

Here are the LCD segment connections to the SM-510.


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