U1
Sharp LR35902 (DMG-CPU)
SoC
Main SoC
About this component
The DMG-CPU contains the SM83 processor core (an 8080/Z80 hybrid), the LCD controller, the four-channel sound generator, timers, a 256-byte boot ROM and 127 bytes of high RAM. On the original Game Boy both the 8 KB work RAM and 8 KB video RAM are external chips beside it. It runs from a 4.194304 MHz crystal. For no-sound faults, check the separate Sharp IR3R40 audio amplifier (U4) before the SoC. Part variants: Most units are marked DMG-CPU; later units are marked DMG-CPU A (and further letter revisions). Sharp's own name for the chip is LR35902.
What it does on this board
Custom 8-bit CPU @4.19MHz with integrated video and audio.
Pinout & readings
No pinout or reference readings yet — these show what each pin does and what a healthy part should measure.