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(1) Mode registers
COMO!:
00 Copy (FB - > FB, copy within same plane)
01 PCopy (copy from one plane in FB ->other planes in FB)
****
10 HWrite (Host - > FB), Dot Write
11
HRead ( FB - > Host)
These are further modified by COM2 and COM3.
COM2:
Puts pattern from source,
a
16 - pixel wide rectangle,
in a one - line
destination.
COM3:
Sets the mask pattern from the host once each write for a masked rep.
Also, during Copy or PCopy execution within FB, it is necessary to return the copy
direction based on the source rectangle and destination rectangle positions.
Source X address
<
destination X address
->Direction in which the X address is reduced (to the left),
XINC
is 0. Otherwise, direction in which the X address is in - creased (to the
right), XINC is 1.
Source Y address
<
destination Y address
->Direction in which the Y address is reduced (to the left),
YINC
is 0. Otherwise, direction in which the Y address is in - creased (to the
right), YINC is 1.
XINC: Signal which controls the address chip (uPD65013G)
0: Direction in which the X address is reduced (both source and destination)
1: Direction in which the X address is increased (both source and destination)
YINC: Signal which controls the address chip (uPD65013G)
0: Direction in which the Y address is reduced (both source and destination)
1: Direction in which the Y address is increased (both source and destination)
XEDR:
Signal which controls the raster chip (raster chip XEDR)
Switches internal shift register input.
0: Switches shift register input to data register.
1: Switches shift register input to data from FB.
DOTM:
Signal which controls the raster chip and exec flag
O: Read/write in word ( 16 - pixel) uni ts.
1: Read/write in pixel units.
(2) Req and exec flags
ROCC start, stop and wait are controlled by the req and exec flags.
rec exec
description
0
0
Stop/idle (completion of command)
1
0
Start (request to begin command execution)
0
1
Wait (wait to read the write or mask data from the host)
1
1
Executing (FB read/write being executed)
The timing for setting the rec flag is set by QB if the rep command exec flag (Al4)
is
1.
The exec flag is set by /NCK except in the pixel mode.
The timing for clearing the req flag is quite complicated.
Either /clreqO or /clreql is used as the req flag clear signal.
This is determined using a logical OR operation based on the rep mode.
NWS-1510/1530/1580
3-49
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