Commodore Amiga A500 Technical Reference Manual page 123

Negate PC Reset (R)
A
read access to this register negates the
PC
reset line and allows the
(IFFFS / 7FFF5)
PC
to start the boot procedure. On power-on the
PC
reset line is as-
serted (default).
Mode Register
(W) Reading this register returns system configuration information
Bit no. Name Function
0
SERON
serial interface enabled
1 PARON
parallel interface enabled
2 KEYON
keyboard interface enabled
3 MON
monochrome display emulation enabled
4 COLOR
color display emulation enabled
5
SEL1
select the
PCIAT
memory bank, s.b.
6 SE12
select the
PCIAT
memory bank, s.b.
7 PCIAT LOW
=
AT
mode
HlGH
=
PC
mode
Writing to this register sets system configuration information
Bit no. Name Function
0 SERON
1 PARON
2 KEYON
3 MON
4 COLOR
5
SEL1
6 SE12
7 ISTOPCLK
switch serial interface on
switch parallel interface on
switch keyboard interface on
enable monochrome display emulation
enable color display emulation
PCIAT
memory bank select, s.b.
PCIAT
memory bank select, s.b.
LOW
=
disable the clock for video
retrace and keyboard
HlGH
=
enable the clock for video
retrace and keyboard
SELZ SE11 PC memory AT memory
0 0
not used not used
0 1
AOOOO
-
AFFFF
HEX
AOOOO
-
AFFFF
HEX
1 0
DO000
-
DFFFF
HEX
D 4 0 0 0
-
DFFFF
H!3
1 1
EOOOO
-
EFFFF
HEX not used