Glue logic is a possibility, but would require a lot of parts, about 40 latching chips and many lagic gates for bit filtering, transistor would be needed as that would be too much current draw on the pins. An FPGA would be a much more simpler solution. Most likely shift registers would be used to controll 200 LEDs, or WS2812s / APA102s. Both would require soldering to the Gameboy ASIC. Pins A0-A15, D7~D4, CLK, WR, RST, Maybe CS. Address Line [15..09] Must equal to 0x60 [08..03] Chip selector 40 latch chips [02..00] Bit latch enable Data Line [07] Only need one bit [0F 0E 0D 0C 0B 0A 09] [08 07 06 05 04 03] [02 01 00] C000 [01 01 00 00 00 00 00] [00 00 00 00 00 01] [0F 0E 0D 0C 0B 0A 09] [08 07 06 05 04 03] [02 01 00] C008 [01 01 00 00 00 00 00] [00 00 00 00 01 00] [0F 0E 0D 0C 0B 0A 09] [08 07 06 05 04 03] [02 01 00] C010 [01 01 00 00 00 00 00] [00 00 00 00 01 01] [0F 0E 0D 0C 0B 0A 09] [08 07 06 05 04 03] [02 01 00] C018 [01 01 00 00 00 00 00] [00 00 00 01 00 00] ... [0F 0E 0D 0C 0B 0A 09] [08 07 06 05 04 03] [02 01 00] C138 [01 01 00 00 00 00 00] [01 00 00 01 01 01]