DVD Studio Pro - General Purpose Register Memories

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General Purpose Register Memories

The General Purpose Register Memories (GPRMs) provide memory storage that can be
used when building scripts. Unlike System Parameter Register Memories (SPRMs), GPRMs
are not used directly by the DVD player—they are only used by scripts. Values, such as
an SPRM or a value you specify, can be written to a GPRM, have a math operation applied
to it, and can then be used by a script command to control the DVD player.

DVD Studio Pro provides access to eight 16-bit GPRMs. Each register is completely
independent of the others. All of the registers are set to 0 when a disc is inserted into the
DVD player.

When creating scripts, you may find that you could use an additional GPRM or two.
Because you will often not need the full 16-bits of a GPRM register, you are able to increase
the number of GPRM registers by partitioning one or more of them into smaller sizes. For
example, you could choose to partition GPRM 1 into four 4-bit registers. This makes it
possible to greatly increase the usable number of GPRMs available when creating your


Several script command configurations and display conditions require the

use of full 16-bit GPRM registers. For that reason, you are only allowed to partition seven
of the eight 16-bit GPRM registers.


Chapter 20

Creating Scripts

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About SPRMs and Partitioned GPRMs

SPRMs fall into one of three categories:

• Those that use the first bits of their register, such as SPRM 1

• Those that use part of the register, but not the first bits, such as SPRM 14 which uses

bits 8 through 11

• Those that use the entire register, with each bit representing the status of a function,

such as SPRM 15

If you partition a GPRM into four 4-bit registers, then move the same SPRM value into
each register, each of the 4-bit registers would get the same first four bits of the SPRM.

As an example, while SPRM 14 only uses four bits of its register, because they are not
the first four bits, they cannot be moved into a partitioned GPRM register. For this reason,
it is recommended that you always keep several 16-bit GPRMs available.