View mb88201 datasheet:

MB88201 IL08 C-MOS 4-BIT MICROCOMPUTER —TOP VIEW— 9 R0 R6 I/O 1 VDD 16 10 R1 11 R2 R7 I/O 2 15 RESET IN 5 12 R10/START R3 6 13 R11/X R4 R8 I/O 3 14 R5 I/O 7 14 EX R5 1 R6 R9 I/O 4 13 R4 I/O 15 2 RESET R7 3 R8 R10/START I/O 5 12 R3 I/O 4 R9 R11/X I/O 6 11 R2 I/O INPUT EX IN 7 10 R1 I/O EX : EXTERNAL X’TAL RESET : RESET 8 GND 9 R0 I/O START : STANDBY RELEASE OUTPUT R11/X : EXT CLOCK IN/INT CLOCK INPUT/OUTPUT R0 - R11 : I/O PORT (R) 15 RESET 7 ROM RAM EX (512 x 8) (16 x 4) Y PC SP (4) (10) (1) CF AC STACK (1) (4) (9 x 2) ZF (1) ST ALU (1) SC OSC (?6) I/O PORT 6 5 4 3 2 1 14 13 12 11 10 9 R11R10 R9 R8 R7 R6 R5 R4 R3 R2 R1 R0