HP 49g Graphing Calculator - Manual (Page 109)

Port 2
Port 2 is part of the Flash ROM. As with port 1, it is not possible to store
objects larger than 128KB. Flash ROM is organized as 8 areas of 128KB
each and one area of 64KB.
The method that the system uses to manage Flash ROM can sometimes
affect operations in port 2. Wlien it erases data, the system must erase
128Kb areas at a time. It cannot erase single objects. When you delete an
object from flash ROM, the object is simply flagged as deleted. It still
occupies memory space.
Occasionally when you want to store an object in Flash ROM, the system
needs to remove files flagged as deleted. It does this by copying all the
non-flagged object to RAM, erasing the entire Flash ROM, and then
moving the non-tagged objects back to flash ROM.
Depending on how much data you have stored in flash ROM, up to 128KB
of RAM might be needed for this operation. If there is not enough RAM, an
error occurs, and the following message is displayed:
Ins. Mem. Need x bytes.
In this event, to store your object, you need to free up at least x bytes of
RAM.
To list a port’s contents, and find Free memory
You can use the PVARS command to list the contents of a port. The PVARS
command returns a list containing the port mmiber and name of each
object in the port, and the amount of free memory in the port.
Page 11-8 Memory