HP 7470A Interfacing And Programming Manual page 90

negative pen control parameter raises the pen. Use of +99 and -99 is
recommended. Once a pen down parameter has been sent, the pen will
remain down for following X,Y increment moves until a negative pen
parameter is received or the UC command is completed. Upon entry
into a UC command the pen is raised. Each UC command must have
at least one pen down parameter in order to draw anything. A UC
command without a pen down will result in a pen movement of one
character—spacefield horizontally. When a UC command is complete,
the pen returns to its up/ down status as set by PU or PD.
The position of the pen when the UC command is executed becomes the
character origin point. The initial X,Yincrement is relative to the char­
acter origin point and each subsequent move is relative to the last com­
manded pen position. Upon completion of the user defined character,
the pen is automatically moved one character—spacefield to the right of
the character origin point. This point becomes the current pen position
and hence, the character origin point for the next character (if any).
The following example generates a 2 symbol which is the same size as
an uppercase letter. For comparison, an "E" is drawn with the label
command. The example shows how size commands affect both user
defined characters and labeled characters. The HP-GL commands
appear in quotation marks in the BASIC PRINT statements. Other
BASIC statements, FOR and NEXT, are included in this example.
PRINT "IN;SP2;PH1000,1000;"
FUR H=.1S TD .99 STEP .1
PRINT "SI",R,R*1.4
PPINT"uc4,?,9s,o,1,~4,o,2,—4,—2,—4,4,o,o,1;"
NEXT H
PRINT "PR1000,1?50;"
FUR B=.1S TU .99 STEP .1
PRINT "SI",B,B*1.4
PRINT "LBE&"
NEXT B
:——
u—:n
EEEEE:i
222222 E 3:
User defined characters need not fit into a single character—spacefield.
In the next example, the user defined character takes up more than one
character space. Since this character is to be followed by a label, a CP
command must be added to move the current pen position beyond the
limits of the user defined character. The reference point for parameters
5-20 LABELING