Peritek VCD-V, User Manual

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Peritek
5-48 Programming On-board Devices and Memories
Table 5-27 BT468 registers
VMEbus
Offset Mnemonic Function
3 CMAPARL Low byte of BT468 address register. Two bit low
order internal counter addresses individual R, G,
and B locations when color maps are accessed.
(See description above).
7 CMAPARH High byte of BT468 address register. See
description above.
B CSRMAP BT468 control/status buffer, cursor position
control and bit map, zoom control, and cursor
and overlay color maps.
F PRIPAL Primary plane color map palette. 256 x 3 (R,G,B)
locations. R,G,B locations cycled by mod-3
counter.
The following table and block diagram show what color value you get
depending on the various inputs to the color map (inputs are called Cursor
Overlay, Graphics Overlay and Primary Screen).
Table 5-28 BT468 Color Map Input Conversion
Cursor Overlay Primary
Input Input Input Color Value
0 0 00 primary palette entry 0
. . . .
0 0 FF primary palette entry FF
0 1 xx overlay palette entry 1
. . . .
0 F xx overlay palette entry F
1 xx xx cursor palette entry 1
2 xx xx cursor palette entry 2
3 xx xx cursor palette entry 3