HP 262SA - Page 302

Graphics
BINARY SHORT INCREMENTAL FORMAT. The short incremental format uses two
bytesto specify a
delta X and a delta Y in the range-16 to +15.Thefive least significant bits are
interpreted as a signed, two's complement number. This number is added to the current pen
position to obtain the new end point. The data bytes are ordered as follows:
BIT
BYTE 1
BYTE 2
7 6
o 1
o 1
5 4 3 2
( DELTA X )
(
DELTA Y )
The following example illustrates the computation and use of the short incremental format:
DELTA X = -12 = 10100 DELTA Y = 6 = 00110
BYTE1 01 10100 4 DELTA X
BYTE2 01 00110 = & DELTA Y
The following sequence moves the pen to 360, 180 in absolute format, then draws a vector to X
= 360-12 = 348, y = 180+6 = 186.
Ec * pia + ( /4 j 4 & (byte1)(byte2) ... Z
BINARYINCREMENTAL FORMAT. Incrementalis similar to short incremental, but with
a larger range. Using six bytes, delta X and Y can range from -16384 to +16383.
BIT 7 6
5
4 3
2 1
BYTE1 0 1 DX14 DX13 DX12 DX 11 DX10 HI
DELTA
X
BYTE2 0 1 DX9 DXa
DX7
DX6 DX5 MID DELTA
X
BYTE3
0
1
DX4 DX3 DX2 DX1 DXO LOW DELTA
X
BYTE4
0
DY14 DY13 DY12 DY11 DY10 HI DELTA
Y
BYTE3 0 DY9
Dya
DY7
DY6 DYS MID DELTA
Y
BYTE2
0
DY4 DY3 DY2 DY1
DYO LOW DELTA Y
The following example shows how incremental data bytes are generated.
DELTA X = -400 = 11111
1
0011
10000
HI DX MID DX LO DX
DELTA Y
100 00000
00011 00100
HI DY MID DY
LO DY
BYTE 1 01 11111 HI DELTA X
BYTE 2
01 1 0011 3
MID DELTA
X
BYTE
3 01 10000
0
LO DELTA
X
BYTE
4 01 00000
space
HI DELTA Y
BYTE
5 01 00011
#
MID DELTA Y
BYTE 6
01
00100
$
LO DELTA Y
D-32