dot
pattern specified by the user. No operation
is
performed when this sequence
is
executed modes 0,
1,
or
2. The elements
of
the sequence are as follows:
Byte
1:
Byte
2:
Byte
3:
Byte
4:
Byte
5:
Byte 6:
Byte 7:
Byte
8:
Byte 9:
Byte
10:
Byte
11:
Byte
12:
Byte
13:
Decimal
27
Decimal
198
Hexadecimal
1B
Hexadecimal C6
High byte
of
horizontal starting position
Low byte
of
horizontal starting position
High byte
of
vertical starting position
Low byte
of
vertical starting position
High byte
of
horizontal ending position
Low byte
of
horizontal ending position
High byte
of
vertical ending position
Low
byte
of
vertical ending position
First byte
of
mask
pattern
Second byte
of
mask
pattern
Function
The starting
and
ending positions are specified as two-byte hexadecimal num-
bers which indicate co-ordinates
in
the
graphic screen.
For
example, starting
co-ordinates
of
400,20 (&HOI90,&HOOI4) would be specified as follows:
Byte
3:
Byte
4:
Byte
5:
Byte 6:
1 (&H01)
144 (&H90)
°
(&HOO)
20 (&HI4)
The mask
pattern
used for drawing the line
is
specified
in
bit image format as
described in the explanation
of
the
LINE
statement in Chapter 4
of
the
PX-8
BASIC Manual. Calculations for diagonal lines are performed automatically.
Function
is
specified as a number from 1
to
3 with the following meanings:
1:
OFF
2:
ON
3:
Complement
Dot
positions corresponding
to
"1"
bits
in
the
mask
pattern
are re-set (turned
off) when 1
is
specified for the function
and
are set (turned on) when 2 is speci-
fied. When 3
is
specified, the complements
of
dots corresponding
to
"1"
bits
are displayed (ON dots corresponding
to
"1"
bits are turned off,
and
OFF
dots
are turned on).
A-12
An
example
of
specification
of
this sequence as follows draws a line from point
(400,18)
of
the
screen
to
point (18,18):
Decimal 27,198,1,144,0,18,0,18,0,18,170,170,2
Hexadecimal IB,C6, 1 ,90,0, 12,0, 12,0, 12,AA,AA,2
This
command
duplicates the
LINE
command
of
BASIC,
but
also allows the
dots
to
be inverted (i.e. switch them
on
if
they are
off
and
vice versa), which
LINE
does not.
ESC
199
This escape sequence sets
or
re-sets the specified points
of
the
graphic screen.
No operation
is
performed
if
this sequence
is
executed in modes 0,
1,
or
2 .. The
sequence consists
of
six bytes as follows:
Byte
1:
Decimal
27
Hexadecimal 1 B
Byte
2:
Decimal 199 Hexadecimal C7
Byte
3:
Function code (1: PSET,
0:
PRESET)
Byte
4:
Vertical
dot
position -
nl
Byte 5: High byte
of
horizontal dot position - n2
Byte 6: Low byte
of
horizontal dot position
Numbers specified for
nl
and
n2 must be
in
the
following ranges:
Decimal
O~nl
~63,
0~n2~479
Hexadecimal
O~nl
~3F,
0~n2~
IDF
ESC
208
Switches the display mode.
Mode
specification is as follows:
Dec
Hex
Dec Hex
Mode °
Mode 2
Byte
1:
27
IB
Byte
1:
27
1B
Byte
2:
208
DO
Byte
2:
208
DO
Byte
3:
2 2
Byte
3:
2
2
Byte
4:
nl nl
Byte
4:
nl
nl
Byte
5:
n2
n2
Byte
5:
m
m
Byte
6:
p
p
Mode 1 Mode 3
Byte
1:
27
IB
Byte
1:
27
1B
Byte
2:
208
DO
Byte
2:
208
DO
Byte
3:
1 1
Byte
3:
3
3
Byte
4:
nl
nl
A-13
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