Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 78
I92 controls bits A31 through A24 of the VME bus base address of Turbo PMAC, both for the mailbox
registers, and the dual-ported RAM. It is only used if 32-bit addressing has been selected with I90 and
I99.
I92 is actually used at power-on/reset only, so to set or change bits 16-23 of the VME bus base address,
change the value of I92, store this new value to non-volatile flash memory with the SAVE command, and
reset the card with the $$$ command. The active register into which the value of I92 is copied at power-
on/reset is X:$070008 bits 0 – 7. It is permissible to write to this register directly (suggested M-variable
M92) to change the active setup without a SAVE and reset.
I93 VME Mailbox Base Address Bits A23-A16 ISA DPRAM Base Address Bits A23-
A16
Range: $00 - $FF
Units: None
Default: $7F (VME); $0D (ISA)
On VME bus systems, I93 controls bits A23 through A16 of the VME bus base address of the mailbox
registers for Turbo PMAC. Bit 7 of I93 corresponds to A23 of the base address, and bit 0 of I93
corresponds to A16. I93 is only used on VME systems if 24-bit or 32-bit addressing has been selected
with I90 and I99.
On ISA bus systems (PC, PC Ultralite, 3U Turbo with PC/104), I93 controls bits A23 through A16 of the
ISA bus base address of the DPRAM. Bit 7 of I93 corresponds to A23 of the base address, and bit 0 of
I93 corresponds to A16. A23 through A20 are only used on ISA bus systems if bit 2 of I94 is set to 1,
enabling 24-bit addressing.
Note:
When DPRAM is used on the PCI bus, Universal Serial Bus (USB), or Ethernet,
the host address is set by a “plug-and-play” process, and I93 is not used.
I93 is actually used at power-on/reset only, so to set or change the base address, change the value of I93,
store this new value to non-volatile flash memory with the SAVE command, and reset the card with the
$$$ command. The active register into which the value of I93 is copied at power-on/reset is X:$070009
bits 0 – 7. It is permissible to write to this register directly (suggested M-variable M93) to change the
active setup without a SAVE and reset.
I94 VME Mailbox Base Address Bits A15-A08 ISA DPRAM Base Address Bits A15-
A14 & Control
Range: $00 - $FF
Units: None
Default: $A0 (VME); $45 (ISA)
On VME bus systems, I94 controls bits A15 through A08 of the VME bus base address of the mailbox
registers of Turbo PMAC. Bit 7 of I93 corresponds to A23 of the base address, and bit 0 of I93
corresponds to A16. I94 is used whether 16-bit, 24-bit, or 32-bit addressing has been selected with I90
and I99.
On ISA bus systems (PC, PC Ultralite, 3U Turbo with PC/104), I94 controls the enable state and
addressing mode of the DPRAM. If the DPRAM is to appear as a 16k block of memory on the ISA bus,
it also sets bits A15 and A14 of the ISA bus base address.
The first hex digit of I94 contains bits 4 – 7. When the DPRAM is addressed as a 16k x 8 block of
memory on the ISA bus, bit 7 of I94 corresponds to A15, and bit 6 of I94 corresponds to A14. Bits 5 and
4 must be set to 0. When the extended 32k x 8 DPRAM is addressed as a 64k x 8 block of memory on
the ISA bus, bits 7 through 4 of I94 must all be set to 0.