Using Displays
Display Timing Parameters
11-16
SPARCbook Portable Workstation User Guide
Display Timing Parameters
The hardware timing parameters for a display are derived from the time
taken to output one pixel, which is controlled by the pixel clock (or dot
clock), from the time it takes to scan one line and from the time it takes
to scan the whole display.
The display interface generates two synchronization signals. One for
horizontal (line) and one for vertical (frame) synchronization. These
signals may be supplied to the display on separate wires, combined onto
one composite sync on one wire, or combined with the green video
channel (sync on green).
Typical characteristics for horizontal and vertical synchronization and
blanking signals are illustrated in Figure 11-6.
The waveforms for the horizontal and vertical sync signals are similar
in shape but differ in that the horizontal parameters are measured in
pixels or dots while the vertical parameters are measured in lines. So,
for example, a 1024 x 768 display would have 1024 visible dots
horizontally and 768 visible lines vertically.
The total time for the horizontal and vertical sync signals include the
horizontal and vertical blanking periods when the electron beam is
switched off, during which time the display prepares to display the next
Figure 11-6 Video Timing Signals
Back
Sync
Width
Visible Video
Front
Porch
Porch
BLANK
SYNC
Blanking
S3UG4_Book Page 16 Friday, August 8, 1997 11:37 am
