HP 8920A Programmer's Manual page 360

Chapter 6, Memory Cards/Mass Storage
Using RAM Disk
Initializing RAM Disks
360
Each RAM Disk unit must be initialized before it can be used. Unit 0 can be
initialized using the RAM_MNG procedure stored on internal ROM Disk.
Volumes 1, 2, and 3 must be initialized from the TESTS (IBASIC Controller)
screen.
The optional "unit size" parameter in the following procedure specifies the
memory area, in 256 byte blocks, set aside for each disk unit.
Follow these steps to initialize volumes 1, 2, or 3:
1. Access the TESTS (IBASIC Controller) screen.
2. Using the rotary knob or an external terminal, enter and execute the IBASIC command:
INITIALIZE ":MEMORY,0,<unit number 1-3>",<unit size>
For example:
INITALIZE ":MEMORY,0,1",50