home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The Datafile PD-CD 3
/
PDCD_3.iso
/
pocketbk
/
utilsm
/
oplrefdoc
/
ReadMe
< prev
Wrap
Text File
|
1995-04-02
|
5KB
|
102 lines
ReadMe file for OPL_Ref (27-Feb-95)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
What this is
~~~~~~~~~~~~
This is an Impression Publisher/Style version of OPLREF/ZIP, a Psion/Pocket Book II
database file of OPL commands specific to the 3a/Pocket Book II - the original file
can be found on Arcade BBS and elsewhere. Acorn make a Programming Manual which
contains many OPL tutorials and command reference sections, if you are new to
programming you may find this document insufficient for your needs (it only contains
reference information with a few use-examples).
OPL_Ref is A4 and should be printed 'backed-up' (printed on both side of the paper).
See the section on Printing Hints for further information.
The OPL Language
~~~~~~~~~~~~~~~~
If you know BBC BASIC then you should get on well with OPL, however there are one or
two pitfalls to catch you out. As these are not immediately obvious in OPL_Ref, the
main differences are detailed below:
Acorn-Esc aborts a running program.
Program flow: OPL executes the first PROC and then exits therefore use the
first procedure to control the rest of your code - it's a bit like C's
main.
You are forced to declare whether a variable is LOCAL or GLOBAL before you
can use it.
Variable names can be a maximum of 8 characters - no longer. If a variable
ends in $ (string), % (integer +32767 to -32768 only), & (long integer +2147483647
to -2147483648) then the last identifying character uses up one of your eight.
Unless specified in this manner, variables are floating point. The machine works
fastest with integer variables.
Array%(5) creates a five element integer array as normal, but Str$(5) means
'create a string variable which can contain five characters maximum' - you must
specify length when you create a string variable.
There are no two dimensional arrays! If you see Str$(20,10) in OPL it means a
string array of 20 elements, each 10 characters maximum.
OPL is largely case insensitive: Pocket% and pocket% are the same variable. Don't
create variables with the same name as OPL keywords.
Acorn-T translates your OPL code into an OPO (a 'runable' program). After successful
translation you are invited to run your code (it will also appear as a file under
the RunOpl icon on the Desktop).
You can also create OPA's (OPL Applications) with their own icon, etc - see the APP
keyword for details. OPA's must be installed from the Desktop's 'Apps' menu before
they can be run. There is usually no need to remove and re-install if you change the
OPL code and re-compile.
That's all, there was something else but I can't think of it right now... :(
Authors
~~~~~~~
nhealey@cix.compulink.co.uk did all the hard work and suggests you send comments, bugs
etc to that address - BEWARE if it looks like a layout error then it's my fault! To
avoid any (mutual) embarrassment I suggest you contact me in the first instance:
Internet jdstaples@arcade.demon.co.uk
FidoNet James D. Staples at 2:254/27.0 (User 1576, Arcade BBS)
Printing Hints
~~~~~~~~~~~~~~
Impression has excellent control over how pages are printed; you'll need to know
your way around the Print dialogue boxes (covered in Impression's manual). If you
are an experienced Impression printer you can stop reading now - hope you find
OPL_Ref useful!
If you view OPL_Ref, imagine the rings of a ring binder running down the centre of
the pages. The first left hand page is nonexistent, the first right hand page is the
cover sheet and if this page were turned, on the rear you would find the first page
of the index (which is a double page spread). Turn the right hand index page over
and on the rear is page one of the main section.
First you should print all the left hand pages only then reload the paper and print
just right hand pages on the reverse side.
If, after the first print run, you have successfully printed one face of the paper
but now all of the sheets are in reverse order then don't panic: there is a Reverse
switch in the Print dialogues: Impression can print documents backwards (Satan!).
When Impression says 'Print From 1 to 9', etc it doesn't mean the numbers on the
bottom of the sheets you will print. OPL_ref page numbering starts with '1' on page
five; page one is blank, two is the cover sheet, three and four are the index. Subtract
4 from the physical page number to get that particular OPL_Ref numbered page.
That's it - mail me if you have printing problems. If you have OPL problems please
don't mail me; they are your problems, you own them, I don't want to share them with
you ;)
James
Loughborough, UK
PocketFS, Edit, Zap, BASIC, Publisher and Hatris were used in the creation of OPL_Ref.