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HP 48G Calculator - Resetting the Calculator

Introduction
Sometimes it is necessary to reset the HP 48G series calculator. Several types of resets are available; this document lists the three most common.
System halt reset
A system halt will interrupt and cancel all executing programs and system operations. The stack and the temporary system storage section of memory will be cleared, and the calculator will return to the {HOME} directory with the [MTH] menu keys displayed.
To halt the system using the keyboard, do the following:
  1. If necessary, turn the calculator on.
  2. Press and hold the ON key.
  3. Press the C key.
  4. Release both keys at the same time.
Halting the system using the reset hole
 caution:
With this reset, there is a chance of affecting the memory. Read all the steps before performing the reset.
Place the calculator face down, and do the following:
  1. Remove the upper-right rubber foot. Underneath the foot is a reset hole with the letter "R" beside it. If the hole does not have an "R" beside it, remove the upper-left rubber foot and check the reset hole beneath it.
  2. Straighten and insert an average-gauge metal paper clip into the reset hole labeled "R" until it hits bottom and hold it there for at least two seconds.
  3. Remove the paper clip, turn the calculator face up, and press the ON key. This should cause the machine to reset, and in some cases display the message "Try to recover memory?"
  4. If the "Try to recover memory?" message appears, press the A key to attempt to recover memory or the F key to erase the user memory. When A is pressed, occasionally the objects in memory are recovered in new sub-directories of {HOME} labeled D.01, D.02, et cetera. Pressing the F key will cause all information stored by the user to be erased from calculator memory.
     note:
    This will also affect any RAM card merged with main memory. If the card is not merged, or if it is write-protected, it will not be affected by this reset.
Performing a memory reset
 caution:
The memory will be affected with this reset. Read all of the steps before performing the reset.
A memory reset will return the HP 48G calculator to its factory-default state, which erases all stored user memory. Use this feature very carefully.
  1. Turn the calculator on.
  2. Press and hold the ON, A, and F keys simultaneously.
  3. Release all three keys at the same time. The calculator should display the message, "Try to recover memory?"
  4. Press the A key to attempt to recover memory, or the F key to erase the user memory. When A is pressed, occasionally the objects in memory are recovered in new sub-directories of {HOME} labeled D.01, D.02, and so on, although there is no guarantee that all of the variables will be recovered. Pressing the F key will cause all information stored by the user to be erased from calculator memory.
     note:
    This will also affect any RAM card merged with main memory. If the card is not merged, or if it is write-protected, it will not be affected by this reset.
Freeing a merged RAM card into user memory
  1. Press left shift key, { } key, ENTER key to enter the empty list.
  2. Press left shift key, LIBRARY soft menu [FREE1] key. If the RAM card is already free (port memory), a “Port Not Available” error will appear when FREE1 is executed. If there is not enough memory available to free the RAM card, there will be a memory error when executing FREE1 (see below).
  3. Optional: Turn off the HP 48GX calculator and unplug the card. See the section “Removing a plug-in card” in this document.
     note:
    To check the amount of user memory, press the left shift key, MEMORY key, then the soft menu [MEM]. The number returned is the amount of unused user memory in bytes. To free the RAM card, there must be an unused amount that is greater than or equal to the size of the RAM card. Otherwise, the calculator does not have enough unused memory to allocate to the card.
If there is insufficient user memory to free a RAM card
  • Purge unneeded variables from user memory.
  • Back up data into a RAM card installed in the other card slot, and then purge the original variables.
  • Back up data into port 0, purge the originals, and then move the backup objects to the RAM card as it is being freed (see below).
Freeing a merged RAM card and moving backup objects to it
  1. Back up the desired objects into port 0.
  2. Enter a list (with { }delimiters) containing the simple names of the backup objects in port 0.
  3. Press the left shift key, MEMORY key, soft menu [FREE1] key. The objects named in the list are removed from port 0 and stored in the newly freed RAM card (in port memory).
  4. Optional: Turn off the HP 48 calculator and unplug the card. Refer to “Removing a plug-in card” below.
Removing a plug-in card
 caution:
Never remove a RAM card that contains merged memory. This could cause a loss of data stored in user memory. Before removing the RAM card, the merged memory must be freed.
If a card with merged memory is accidentally removed and the message, “Replace RAM card, Press On” appears, reinsert the card in the same port, and press the ON key.
  1. Before removing a RAM card from Card Slot 1, make sure it contains un-merged, free memory. See the caution above and the Checking the type of memory in a port section below.
  2. Turn off the calculator. Do not press the ON key until the card has been removed.
  3. Remove the port cover.
  4. Press against the grip, and slide the card out of the port.
  5. Replace the port cover.
Checking the type of memory in a port
Enter the port number and press the left shift key, the LIBRARY key, then the soft menu [PVARS]. The result in level one indicates the type of memory:
Display
Explanation
ROM
ROM in an application card.
SYSRAM
Merged user memory in a RAM card.
number
Free port memory in a RAM card.
See above instructions for un-merging a RAM card
 note:
A RAM card must be un-merged before it can be write-protected.

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