
Extension Registers
14-27
`efmp69030 Databook
Revision 1.3 11/24/99
XR88
Alternate Font Location Control
read-only at I/O address 3D7h with 3D6h set to Index 88h
shared by both pipelines A and B
7
Alternate Font Location Enable
0: Disables having the alternate font location in the frame buffer.
1: Enables having the alternate font location in the frame buffer.
6
Reserved
This bit always returns the value of 0 when read.
5-4
Font Select
These two bits select which fonts from VGA-compatible locations in plane 2 will be copied
to the alternate font location.
3-2
Pipeline Vertical Blanking Trigger Select
These two bits select which pipeline’s vertical blanking events will be used to increment the
counter that triggers the copying of fonts from VGA-compatible locations to the alternate
font location.
1
Font Copy Status and Trigger
When read, this bit indicates whether or not a copy operation is in progress.
0: No copy operation is currently in progress.
1: A copy operation is currently in progress.
When written, this bit can be used to immediately trigger a copy operation regardless of the
current state of the counter.
0: Does not immediately trigger a copy operation. Writing a 0 to this bit does nothing.
1: Immediately triggers a copy operation.
0
Reserved
This bit always returns the value of 0 when read.
76
54
32
10
A
&
B
Alt Font
Location En
(0)
Reserved
(0)
Font Select
(00)
Pipeline Vertical Blanking
Trigger Select
(00)
Font Copy
Stat & Trig
(0)
Reserved
(0)
Bits
5 4
Font Selected
0 0
No fonts are selected, and all use of the alternate font location is disabled
just as if bit 7 of this register were set to 0.
0 1
Font A, the one pointed to by bits 5, 3 and 2 of SR03 is selected.
1 0
Font B, the one pointed to by bits 4, 1 and 0 of SR03 is selected.
1 1
Both fonts A and B (i.e., both the font pointed to by bits 5, 3 and 2 of SR03,
and the font pointed to by bits 4, 1 and 0 of SR03) are selected.
Bits
5 4
Font Selected
0 0
No fonts are selected, and all use of the alternate font location is disabled
just as if bit 7 of this register were set to 0.
0 1
Font A, the one pointed to by bits 5, 3 and 2 of SR03 is selected.
1 0
Font B, the one pointed to by bits 4, 1 and 0 of SR03 is selected.
1 1
Both fonts A and B (i.e., both the font pointed to by bits 5, 3 and 2 of SR03,
and the font pointed to by bits 4, 1 and 0 of SR03) are selected.