Peritek
Programming On-board Devices and Memories
5-35
5.5 Vertical and Horizontal Zoom
Note that while CnP (Graphics Subroutine Package) supports zoom, PX
Windows doesn't.
Using VGA Cables and Timing Modes
In order to use a standard VGA cable, you have to set the sync polarities
correctly for the monitor to select the right line mode.
Table 5-16 VGA Timing Modes
vertical line count
Zoom Register Bit
480 lines
400 lines
350 lines
HSYNCPOL
set
set
clear
VSYNCPOL
set
clear
set
VCMODE
clear
clear
clear
Vertical Zoom
The primary and overlay graphics screens are zoomed together vertically
through bits 0-4 of 34020 register DINCL. This is a binary zoom, factors
1, 2, 4, 8, 16, 32.
Due to a bug in the 34020, vertical zoom does not
work properly in interlaced displays
.
Horizontal Zoom
The zoom control register is used not only for horizontal zoom but also to
program the ICS1562 programmable phase locked loop (PLL) pixel clock
which is used in many configurations. For compatibility reasons, the bit
functions can vary considerably on the VCD-V (non-ICS1562) versions -
see the following page. A configuration tag accompanies the VCD-V
which will tell you if your board uses the 1562. If you are unsure, contact
Peritek for assistance.
Summary of Contents for VCD-V
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Page 42: ...Peritek Installing Your Peritek Graphics Board 2 11 Figure 2 3 Jumper Locations for the VCD V ...
Page 94: ...Peritek Theory of Operation 4 15 Figure 4 1 VCD V Block Diagram ...
Page 95: ...Peritek 4 16 Theory of Operation Figure 4 2 VCU V Block Diagram ...
Page 96: ...Peritek Theory of Operation 4 17 Figure 4 3 VCT V Block Diagram ...