B69000 Asiliant Technologies, B69000 Datasheet - Page 96

• Manufacturer Part Number: B69000
• Manufacturer: Asiliant Technologies

Specifications of B69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

CR00
read/write at I/O address 3B5h/3D5h with index at address 3B4h/3D4h set to 00h
7-0
Note:
CR01
read/write at I/O address 3B5h/3D5h with index at 3B4h/3D4h set to 01h
7-0
CR02
read/write at I/O address 3B5h/3D5h with index at address 3B4h/3D4h set to 02h
7-0
&+,36
7
7
7
Horizontal Total
These bits provide either all 8 bits of an 8-bit value or the least significant 8 bits of a 9-bit value that
specifies the total length of a scanline. This includes both the part of the scanline that is within the
active display area and the part that is outside of it.
In standard VGA modes, where bit 0 of the I/O Control Register (XR09) is set to 0, the horizontal
total is specified with an 8-bit value, 8 bits of which are supplied by this register.
In extended modes, where bit 0 of the I/O Control Register (XR09) is set to 1, the horizontal total is
specified with a 9-bit value. The 8 least significant bits of the vertical total are supplied by the 8 bits
of this register. The most significant bit is supplied by bit 0 of the Extended Horizontal Total Register
(CR38).
This 8-bit or 9-bit value should be programmed to equal the total number of character clocks within
the total length of a scanline, minus 5.
For NTSC/PAL output support, CR79 can be used to add a programmable number of pixel clocks
(as opposed to character clocks) to the horizontal total, permitting the horizontal total to be specified
with greater precision.
Horizontal Display Enable End
This register is used to specify the end of the part of the scanline that is within the active display
area relative to its beginning. In other words, this is the horizontal width of the active display area.
This register should be programmed with a value equal to the number of character clocks that occur
within the part of a scanline that is within the active display area minus 1.
Horizontal Blanking Start
This register is used to specify the beginning of the horizontal blanking period relative to the
beginning of the active display area of a scanline.
This register should be programmed with a value equal to the number of character clocks that occur
on a scanline from the beginning of the active display area to the beginning of the horizontal
blanking.
69000 Databook
Horizontal Total Register
Horizontal Blanking Start Register
Horizontal Display Enable End Register
6
6
6
5
5
5
Subject to Change Without Notice
Horizontal Display Enable End
CRT Controller Registers
Horizontal Blanking Start
4
4
4
Horizontal Total
3
3
3
2
2
2
Revision 1.3 8/31/98
1
1
1
0
0
0
9-3