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Section 8: Program Editing 141
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By pressing R/S as the listing of
CATALOG 1 was in progress, you could stop
the listing and the calculator would be positioned to the label or
END displayed. You could then press SST or
BST to locate and position the calculator
to the desired program in program memory.
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The PACK function
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For your convenience during editing sessions, the HP-41C inserts extra
blank lines in your programs. These blank lines are invisible to you; you
cannot see them in program memory. They are placed in your programs to
assure that while you are inserting and deleting instructions, the
calculator responds to your commands as quickly as possible.
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There are several ways that the HP-41C automatically removes these extra
lines when you are through editing. This is called
‘‘packing.’’
Following is a summary of the times that the HP-41C automatically packs program
memory.
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1.
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Any time you execute CLP (clear program),
program is packed.
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2.
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Any time you attempt to insert a line into a program when there is not
enough room in program memory, program memory is packed. When the packing
is complete, the calculator will display
PACKING and you should reinput
the desired line.
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3.
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When you press
GTO · ·
program memory will be packed. If there is still not enough room in
program memory to insert an END , the calculator
will display
TRY AGAIN . There is now not
enough room in program memory for any more instructions and you should change
the program memory allocation before you continue.
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4.
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Any time you attempt to assign an HP-41C function to a key using
ASN , and there is not enough room in program memory
for the HP-41C to record the assignment, program memory will be packed. When
the pack is complete, the HP-41C will display
TRY AGAIN and you should
again press the keys necessary to assign the function to a key.
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You can cause program memory to be packed at any time by executing
the PACK function. ( PACK is
not programmable.)
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A typical pack will take a few seconds. During this time, the display
will show PACKING . The
result of packing memory is that the programs will run faster after
packing.
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Problems
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1.
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The following program calculates the time it takes an object to fall
to earth when dropped from a given height. (Friction from the air is
not taken into account.) When the program is initialized by keying in
the height h in meters into the X-register and the program is
executed, the time t in seconds the object takes to fall to earth is
computed according to the formula:
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