IBM RT Series Hardware Reference Manual page 102

RAS Status Register (X'0150') Read Only
Bit 0 1 = Even 0 = Odd field
Bit 1 Horizontal sync toggle latch
Bit 2 0
=
Vertical sync inactive 1
=
Vertical sync active
Bit 3 Reserved
Bit 4 1= X 0 = Y Stepping
Bit 5 1 = Interrupt pending
Bit 6 0
=
Increase 1
=
Decrease the address counter
Bit 7 1
=
Enable load address
Bits 8-13 Serialized Color Video
Bit 8
Red (Rl)
Bit 9 Red intense (R2)
Bit 10 Green (Gl)
Bit 11
Green intense (G2)
Bit 12 Blue (Bl)
Bit 13 Blue intense (B2)
Bits 14-15 Reserved
Video Look-up Table Register X'0158' Write
Only
The video look-up table is selected via the I/O channel address. The data written, specified on the
I/O channel most significant byte (bits 0 through 5), is written to the address specified on the I/O
channel least significant byte (bits 0 through 3). To avoid scintillation of the screen, this operation
should only be performed during vertical blanking.
10 Advanced Color Graphics Display Adapter