Z90251 Datasheet, PDF (35/97 Pages) Zilog, Inc. – eZVision 200 Television Controllers with OSD

Z90255 ROM and Z90251 OTP
32 KB Television Controller with OSD
27
Bit/
Field
Bit
Position
R/W Value Description
Reserved
7
R
0 Return 1
W
1 No effect
HV_SYNC Interrupt Option 6
R/W 0 Interrupt Pending Disabled
1 Interrupt Pending Enabled
Second Color Position
5,4,3,2,1,0 R/W
Specifies start position of the
color change to the second
color.
Note:
Column increment is 0.5. Offset is 03h. System software
requires that the offset be added to the increment for the
second color in the bar display. The bar position must be
defined before the second color is enabled.
Bit 6, HV_SYNC Interrupt Option, defines the procedure for processing when a
second interrupt is issued before the first interrupt has completed processing. If
bit 6 is set to 0, bit 6 is not pending the other interrupt (H_SYNC or V_SYNC) while
one is in service. If bit 6 is set to 1, bit 6 is pending the other interrupt (H_SYNC or
V_SYNC) while one is in service.
Figures 9 is an example of second color display in the eighth row of the OSD.
Each of the small grid squares represents one pixel. Each column has two areas
for second color display. In this example, the second color is at Position 6. The
second color position for the first column has a value of 3 because the OSD is
offset from the left of the TV screen at a distance equal to 03h. Each column is
the size of one display character. Each Second color column is a half character
column. The screen position offset is added to Second color position. Because
the offset is 03h, the Second color postions begin with 3 = (3+0), 4 = (3+1), 5 =
(4+1), and so forth.
PS001301-0800