Vga Graphics Registers - AMD M56 Reference Manual

VGA Registers
2.6.5

VGA Graphics Registers

VGA Graphics Registers
Field Name
GRPH_IDX
GRPH Index Register
Field Name
GRPH_DATA
GRPH Data Register
Field Name
GRPH_SET_RESET0
GRPH_SET_RESET1
GRPH_SET_RESET2
GRPH_SET_RESET3
Set/Reset Register
Field Name
GRPH_SET_RESET_ENA0
GRPH_SET_RESET_ENA1
GRPH_SET_RESET_ENA2
GRPH_SET_RESET_ENA3
Enable Set/Reset Register
Field Name
GRPH_CCOMP
Colour Compare Register
M56 Register Reference Manual
2-178
GRPH8_IDX - RW - 8 bits - DISPDEC:0x3CE
Bits Default
3:0 0x0 VGA graphics index as per VGA specified by IBM
GRPH8_DATA - RW - 8 bits - DISPDEC:0x3CF
Bits Default
7:0 0x0 GRPH data indirect access
GRA00 - RW - 8 bits - VGAGRPHIND:0x0
Bits Default
0 0x0 Set/Reset Map 0
1 0x0 Set/Reset Map 1
2 0x0 Set/Reset Map 2
3 0x0 Set/Reset Map 3
GRA01 - RW - 8 bits - VGAGRPHIND:0x1
Bits Default
0 0x0 Enable Set/Reset Map 0
1 0x0 Enable Set/Reset Map 1
2 0x0 Enable Set/Reset Map 2
3 0x0 Enable Set/Reset Map 3
GRA02 - RW - 8 bits - VGAGRPHIND:0x2
Bits Default
3:0 0x0 Colour Compare Map bits 3:0. In Read mode (GRA05[3] being logi-
cal 1), the 4 bits from this register are compared with the 4-bit PEL
value (made up of one bit from each map), from bit positions 0
through 7. As long as the colour don't care bits (GRA07[0:3]) for the
respective maps are logical 1's, the compare takes place only on
those bits of the PEL value, and the CPU reads a one for a match in
that bit position. If Colour Don't Care bit for one map is a logical zero,
the latched data from the map is excluded from the compare, and
only the remaining three bits are compared to generate bus data.
Description
Description
Description
Description
Description
© 2007 Advanced Micro Devices, Inc.
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