Psion II OPL Reference Guide

Miscellaneous

Placeholders in this reference
Variables
Useful Addresses
Defining a User Defined Graphic (UDG)
Tips & Tricks

Variables

Integer%		-32768..+32767 floats will be truncated (not rounded) if used for integer arguments
Float		-1E100..+1E100 (exclusive), 12 digits
String$		must be sized in declaration, size 1..255
Field[%\|$]		up to 16 fields for one record may be defined via CREATE/OPEN (max. len. altogether: 255 - no. of fields)
m0-m9		calculator variables (no declaration, keep values after end of program)

Important note:
Mind that any (partial) expression with only integers will result an integer even if stored in a float!

e.g. a%=5 :b%=3

x=a%/b% 1.0

x=flt(a%)/b% 1.66666666667

x=a%/b%*1.0 1.0

x=a%*1.0/b% 1.66666666667

Useful Addresses

$180,$181	UDG Declaration (see below)
$69,$6A	Horizontal scroll delay counter (default: 4)
$6B,$6C	Vertical scroll delay counter (default: 10)
$77	Keyboard auto-repeat delay (default: 15)
$78	Keyboard auto-repeat counter (default: 0)
$7C	Auto-switch-off flag (default: none-zero)
$20CB,$20CC	system counter (incremented every 50 millisecs)
$20CD,$20CE	default number of secs to auto-switch-off (default: 300)
$A4	buzzer mute flag (default: zero)
$74	key buffer count (max. 16)
$73	key buffer offset (should be set to 0 before pasting into buffer)
$20B0-$20BF	keybuffer
$20C5-$29CA	system clock (year,month,day,hour,minute,second)

Note: A comprehensive list of system adresses can be found in Jaap's Machine Code Tutor.

Defining a User Defined Graphic (UDG)

UDGs (they'd better be called User Defined Characters) are defined with the UDG command on the LZ or the replacement procedure which is also documented at UDG. Up to 8 characters (CHR$(0)..CHR$(7)) may be defined.

See the example below to find out how to calculate the parameters:

	16	8	4	2	1	row sum
p1%						= 6
p2%						= 9
p3%						= 9
p4%						= 12
p5%						= 8
p6%						= 24
p7%						= 31
p8%						= 0

Tips & Tricks

More than one command in a line

The colon acts as command seperator, it must be preceeded by space.

eg. AT 5,2 :PRINT "Hello World";

Call external procedures/functions

Any OPL-program on any pack can be called by from another program by its name followed by ':' and the parameters (if any) in brackets. Parameters must match in number and type!

The name of a function returning a string must end with '$'

prog1:
      prog2:(a$,b%)
      x=func1:
      x%=func2%:(a%)
      x$=func3$:

Check if pack is present

When a pack is sized (i.e. formatted) by the Organiser, a file 'MAIN' is automatically generated.

      print "pack present in"
      if exist("B:MAIN") :print "B:", :endif
      if exist("C:MAIN") :print "C:"; :endif
      get

Make sure that keybuffer is empty

In the following example, the user must respond to the prompt, all keys typed ahead are discarded by the second line of code.

      print "Press any key to continue";
      while key: endwh
      get

e.g.	a%=5 :b%=3
	x=a%/b%	1.0
	x=flt(a%)/b%	1.66666666667
	x=a%/b%*1.0	1.0
	x=a%*1.0/b%	1.66666666667