TUTORIAL 2: HP48 Objects and variables

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What are objects?

An object is simply anything that can be put onto the stack.

Object types

• Numbers
• Alphabetical strings
  Delimited by " "
• Programs
  Delimited by << >>
• Lists
  Delimited by { }
• Vectors & Matrices (arrays)
  Delimited by [ ]
• Algebraic terms
  Delimited by ' '
• Names of objects
  Also delimited by ' '

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Where to store objects

Data (objects) can be stored in memory in three main ways

• The stack
  Objects(e.g. numbers) can be left on the stack and manipulated by various stack manipulation commands (see later..)
• Global variables
  An object can be stored in a "variable" for later retrieval. Variables are shown in the menu bar by pressing [VAR] These are called GLOBAL variables.
• Local variables
  An object only used temporarily within a program ( i.e. not saved ) is called a local variable. After the program has run, local variables are cleared.

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Manipulating the stack

Manipulation of the stack, ensures that a program will run at maximum speed, and economise on memory at the same time. DROP & SWAP commands are on the keyboard. Other stack commands are shown by pressing [L-S][Cursor-up].
Stack commands

• DROP
  Deletes level one of the stack
• SWAP
  Swaps levels and 1 & 2
• OVER
  Copies level 2 into level 1, pushing old level 1 to 2
• ROT
  Moves level 3 to level 1, pushing up the stack
• ROLL
  Moves a specified level to level 1
  ( e.g. 4 ROLL will move level 4 to level 1 )
• ROLLD
  Moves level 1 to a specified level
  ( e.g. 7 ROLLD will move level 1 to level 7 )
• PICK
  Copies a specified level to level 1
  ( e.g. 5 PICK will copy level 5 to level 1 )
• DEPTH
  Counts the number of active levels in the stack placing the number on level 1
• DUP
  Copies level 1 ( i.e. levels 1 & 2 are the same )
• DUP2
  Copies levels 1 & 2 ( i.e. levels 3 & 4 will be the same as 1 & 2)
• DUPN
  Copies a specified number of levels again
  (e.g. 6 DUPN will copy the first six levels of the stack again)
• DROP2
  deletes levels 1 & 2
• DRPN
  a specified number of levels are deleted
  ( e.g. 4 DRPN will delete levels 1 to 4 )

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Memory management

To check the available memory of the calculator
[L-S] [VAR] (MEMORY) |MEM|

To check the size of an object

Put the name of the object on level one.
[L-S] [VAR] (MEMORY) |BYTES|

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Variable management

The HOME directory is the "Root" directory of the calculator. Sub-directories are indicated by a little bar above the menu label.

the current path

The directory path leading to the current directory is shown in the message area of the display within
{ HOME ........ }

To get to the HOME directory, from anywhere

Press [R-S] ['] (HOME)

To move up a directory level

Press [L-S] ['] (UPDIR)

To view variables in the current directory

Press [VAR]

If there are more than 6 objects in the directory: Press [NXT] to scroll across the selection.

To scroll in reverse
Press [L-S] [NXT] (PREV)

To delete (purge) an object

Put the name of the object on level 1
Press [L-S] [EEX] (PURGE)

To create a Sub-directory

Press [alpha] [alpha] Name of subdirectory [ENTER]
Then either: [L-S] [VAR] (MEMORY) |DIR| |CRDIR|
or [alpha] [alpha] CRDIR

To remove a sub-directory Be careful !

Put the name of the sub-directory on level one
then: [L-S] [VAR] (MEMORY) |DIR| |PGDIR|

To copy an object or sub-directory to another directory

Put the name of the object on level, press [ENTER] to duplicate it
Press [R-S] [STO] (RCL) to recall the object to the stack
Get into the destination directory
Press [Right-cursor] to swap
Press [STO]

To move an object to another directory

Follow the same steps for copying and purge the old object.

To rename an object or sub-directory

Put the name of the object on level, press [ENTER] to duplicate it
Press [R-S] [STO] (RCL) to recall the object to the stack
Press [alpha] [alpha] NEWNAME [ENTER] [STO]
Purge the object OLDNAME

To change the ORDER of objects in the varaible menu

Press [L-S] [+] ({})
Press the menu keys of each object in the desired order you wish them to appear in the menu display.
Press [ENTER]
Press [L-S] [VAR] |DIR| |ORDER|

To edit an object (including programs)

Put the name of the object on level 1
Press [L-S] [+/-] (EDIT)
After editing the object press [ENTER] to save changes

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Last Update: 18th March 2001
Richard Stanaway