The custom LSI is a 100-pin single chip LSI on which the
MZ-800 memory controller (I/O controller) and CRT
controller, etc. are contained.
Used for the control of the memory bank. Addressing of
DRAM, ROM, and VRAM is conducted by selection I/O
address, $EO - $E6, using OUT or IN command.
4-2-2. 1/0 controller
In this I/O controller is created the select signal for
assignment of MZ-800 internal device.
See Table-2 for relation of internal device vs I/O
Port B, printer data output
Port A, printer control and timer interrupt
Port B control (Mode 0)
Port A control (Mode 3)
PSG output port
Joystick-2 input port
Joystick-1 input port
Memory bank control
Control port output
(NOTE): Mapped to E007 - E004 in the
Port C, cassette, etc.
(NOTE): Mapped to E003 - EOOO in the
Port B, key input
Port A, key strobe output
TEMP, HBLK input; and 8253 GO ON/OFF output for the MZ-700 mode only.
When above I/O address is accessed, it makes 10WR active for OUT or lORD for IN command.