M69000 Asiliant Technologies, M69000 Datasheet - Page 126

• Manufacturer Part Number: M69000
• Manufacturer: Asiliant Technologies

Specifications of M69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

CR3C
read/write at I/O address 3B5h/3D5h with index at address 3B4h/3D4h set to 3Ch
7-6
5-0
&+,36
Horizontal Blank End
7
Bits 7 and 6
Horizontal Blanking End Bits 7 and 6
The horizontal blanking end is a 6-bit or 8-bit value that specifies the end of the horizontal blanking
period relative to its beginning.
Reserved
These bits should always be written with the value of 0.
69000 Databook
(00)
Extended Horizontal Blanking End Register
In standard VGA modes, where bit 0 of the I/O Control Register (XR09) is set to 0, the
horizontal blanking end is specified with a 6-bit value. The 5 least significant bits of this
value are supplied by bits 4-0 of the Horizontal Blanking End Register (CR03), and the most
significant bit is supplied by bit 7 of the Horizontal Sync End Register (CR05). In standard
VGA modes, this bit is not used.
In extended modes, where bit 0 of the I/O Control Register (XR09) is set to 1, the horizontal
blanking end is specified with an 8-bit value. The 5 least significant bits of this value are
supplied by bits 4-0 of the Horizontal Blanking End Register (CR03), the next most
significant bit is supplied by bit 7 of the Horizontal Sync End Register (CR05), and both the
most significant and 2nd most significant bits are supplied by bits 7 and 6, respectively, of
this register.
This 6-bit or 8-bit value should be programmed to be equal to the least significant 6 or 8
bits, respectively, of the result of adding the length of the blanking period in terms of
character clocks to the value specified in the Horizontal Blanking Start Register (CR02).
6
5
Subject to Change Without Notice
CRT Controller Registers
4
3
Reserved
(00:0000)
2
Revision 1.3 8/31/98
1
0
9-33