Reference Manual

Turbo PMAC/PMAC2 Software Reference

Turbo PMAC Global I-Variables 50

For a Turbo PMAC2 that is not Ultralite or UMAC, the only valid MACRO IC base address is $78400.

For a Turbo PMAC2 Ultralite, the valid base addresses are $78400, $79400, $7A400, and $7B400. For a

UMAC Turbo system, the valid base addresses can be expressed as $7xy00, where x can be 8, 9, A, or B,

and ‘y’ can be ‘4’, ‘5’, ‘6’, or ‘7’.

If the configuration of the MACRO ICs in a modular Turbo PMAC system, such as a UMAC Turbo rack,

is changed, the values of I20 – I23 will need to be changed.

See Also:

I-Variables I20, I21, I23, I24, I4902 – I4903, I4926 – I4941, I6800 – I6999.

I23 MACRO IC 3 Base Address (Turbo PMAC2 only)

Range: $0, $078400 - $07B700

Units: Turbo PMAC Addresses

Default: Auto-detected

I23 sets the base address of the fourth MACRO IC (called MACRO IC 3) in the Turbo PMAC2 system,

normally the one with the fourth-lowest base address. On re-initialization – either on resetting with the

E3 re-initialization jumper ON or on issuing the $$$*** command, Turbo PMAC2 will auto-detect

which MACRO ICs are present, and set I23 to the base address of the MACRO IC with the fourth-lowest

base address. Turbo PMAC2 will also do this when commanded to set I23 to its default value (I23=*).

If less than four MACRO ICs are found, I23 will be set to 0 instead.

I-variables I6950 – I6999 reference registers in MACRO IC 3, whose addresses are relative to the address

contained in I23. These addresses are established at power-up/reset. If the value of I23 is incorrect at

power-up/reset, these I-variables will not work. It is possible to set the value of I23 directly, saving the

value and resetting the card, but users are strongly encouraged just to let Turbo PMAC2 set I23 itself by

re-initialization or default setting, and to treat I23 as a status variable. If I23 is set to 0, these variables

will always return a value of 0.

A Turbo PMAC2 will look to find MACRO nodes 48 – 63 in MACRO IC 3, referenced to the address

contained in I23. These addresses are established at power-up/reset. If the value of I23 is incorrect at

power-up/reset, these MACRO nodes will not be accessed.

UMAC versions of the Turbo PMAC2 have the addressing capability for up to 16 MACRO ICs, but only