The Tom IC (U13) is responsible mostly for outputting video signals.

It has 64 data pins, 24 address pins, clock and RAM signals and a few others, then 24 bit (technically 23 bit, 7 bits for blue) output pins, and a HSL/VSL pin, dedicated to going to the video encoder circuit for outputting video data.

It is unsure yet if it also generates the actual data to output to the encoder (pixel data) or whether that data comes from the Jerry / CPU chips similar to the Lynx Mickey Suzy arrangement where Hayato outputs to the LCD but Suzy is responsible for generating the actual pixel data that Hayato should send.

Alive Test

The Tom IC will not come to life until the BIOS has been successfully loaded into memory.

One noticeable sign of life is to check the HSL (pin 31), or the 74AC74 U6 chip (pin 3). This is a horizontal line pulse and it pulses low once every 63.8us. and every 50 or 60Hz depending on region it outputs a series of longer low pulses several times.