M69030 Asiliant Technologies, M69030 Datasheet - Page 123

• Manufacturer Part Number: M69030
• Manufacturer: Asiliant Technologies

Specifications of M69030

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 70C
• Rad Hardened: No
• Lead Free Status / Rohs Status: Supplier Unconfirmed

CR10
read/write at I/O address 3B5h/3D5h with index at address 3B4h/3D4h set to 10h
shadowed for pipelines A and B
7-0
`efmp
A
B

Vertical Sync Start Bits 7-0
69030 Databook
7
Vertical Sync Start Register
This register provides the 8 least significant bits of either a 10-bit or 12-bit value that
specifies the beginning of the vertical sync pulse relative to the beginning of the active
display area of a screen.
In standard VGA modes, where bit 0 of the I/O Control Register (XR09) is set to 0, this value
is described in 10 bits with bits 7 and 2 of the Overflow Register (CR07) supplying the 2
most significant bits.
In extended modes, where bit 0 of the I/O Control Register (XR09) is set to 1, this value is
described in 12 bits with bits 3-0 of the Extended Vertical Sync Start Register (CR32)
supplying the 4 most significant bits.
This 10-bit or 12-bit value should equal the vertical sync start in terms of the number of
scanlines from the beginning of the active display area to the beginning of the vertical sync
pulse. Since the active display area always starts on the 0th scanline, this number should
be equal to the number of the scanline on which the vertical sync pulse begins.
6
5
CRT Controller Registers
Vertical Sync Start Bits 7-0
Vertical Sync Start Bits 7-0
4
3
2
Revision 1.3 11/24/99
1
0
9-21