M69030 Asiliant Technologies, M69030 Datasheet - Page 93

• 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

MSR
write at I/O Address 3C2h
read at I/O Address 3CCh
partially shared and partially shadowed between both pipelines A and B as shown
7-6
5
4
`efmp
A
B
PIpe A Sync Output Pol
PIpe B Sync Output Pol

Sync Output Polarity
Odd/Even Page Select
Reserved
69030 Databook
7
Miscellaneous Output Register
(00)
(00)
Bit 7 controls the polarity of the VSYNC output, while bit 6 performs the same function for
the HSYNC output. For both of these bits, a value of 0 sets the corresponding sync output
for positive polarity, while a value of 1 chooses negative polarity.
The original VGA standard was created at a time pre-dating the onset of multifrequency
displays that examined clock rates or counted pulses to determine resolutions. Therefore,
different combinations of positive and negative polarities on the sync outputs were used to
set original VGA displays to any one of three modes (depicted in the table below).
However, over time, numerous additional resolutions and alternate timings intended to
improve upon the original VGA standard came to be widely used. In order to maintain
compatibility with the VGA standard, the vast majority of these use HSYNC and VSYNC
outputs that are both configured to be of positive polarity since this was the only choice left
over as ‘reserved’ in the original VGA standard.
0: Selects the lower 64KB page.
1: Selects the upper 64KB page.
Selects between two 64KB pages of frame buffer memory during standard VGA odd/even
modes (modes 0h through 5h). Bit 1 of register GR06 can also program this bit in other
modes.
This bit returns the value of 0 when read.
7 6
0 0
0 1
1 0
1 1
Bit
6
negative
negative
Polarity
VSYNC
Output
positive
positive
Page Select
General Control and Status Registers
(0)
5
negative For standard VGA modes with 400 scanlines.
negative For standard VGA modes with 480 scanlines.
Polarity
HSYNC
positive
positive
Output
Reserved
Not used for standard VGA modes. Often used
for extended modes regardless of the number of
scanlines.
For standard VGA modes with 350 scanlines.
(0)
4
Vertical Resolution Selected
Pipe A Clock Select
Pipe B Clock Select
3
(00)
(00)
2
RAM Enable
Revision 1.3 11/24/99
(0)
1
I/O Address
(0)
0
8-5