84PCE:Ports:Control

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Synopsis

Port Number: 0000-0fff

Function: Master Control

This port range is used to configure and control important things; possibly the reason why it does not have a memory-mapped address. It is mirrored every 0x100 bytes.

If a port is not listed; it indicates that writes have no effect and do not latch, and that reads are 0. Note that this may not be true one hundred percent.

Port Address Space

Port    Default    Information   
0000 03 CPU Speed Control
0001 03 OS Timer Control
0002 Read only, value can change
0003 00 Hardware ID
0005 76 Set bit 5 to freeze, bit 6 affects backlight
0006 03 Display refresh
0007 B7 Latches values written
0008 7F Cannot change value
0009 37 Power control system
000A FD Latches value written
000B F8 Charging Status
000C 00 Latches value written
000D FF Bit 0: Freeze if reset
Bit 1: Crash if reset
Bit 2: No apparent effect if reset
Bit 3: Reset to disable VRAM. Upon set, VRAM is garbage
Bits [7:4]Possibly last value written
000E 0A Latches value written
000F 42 High nibble may be a status, low 2 bits latch value written
001C 80 Cannot change value
001D A7 Privileged address
0020 7C Memory protection
0028 Bit 1 is always 0
0029 00 Bit 0 latches value written
002A 70 Latches value written
002B FE Latches value written
002C Ports 002C-0031 latch value written
0032 Latches value written
0033 Latches value written
0034 Latches value written
0035 Latches value written
0036 Ports 0036-0039 latch value written