Reference Manual
Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 163
I4904 Dual-Ported RAM ICs Present
Range: $000000 – $FF8000
Units: none (individual bits)
Default: --
I4904 is a read-only status I-variable that reports which dual-ported RAM ICs are present in a Turbo
PMAC system. It is provided for user setup and diagnostic purposes only. On power-up/reset, Turbo
PMAC automatically queries for the presence of each possible DPRAM IC and reports what it has found
in I4904.
I4904 is a 24-bit value with the nine high bits currently used. Each individual bit used represents each
possible DPRAM IC that could be present in the system. The bit is set to 0 if the IC is not present; it is
set to 1 if the IC is present.
UMAC accessory boards with DPRAM, such as the Acc-54E UBUS/Ethernet board, provide
identification information in variables I4942 – I4949, depending on their base address.
The following table shows the DPRAM IC each bit of I4904 represents, and the matching identification I-
variable:
I4904
Bit #
Bit Value
Base
Address
Ident
I-var
15
$8000
$060000
None
16
$10000
$06C000
I4942
17
$20000
$074000
I4943
18
$40000
$06D000
I4944
19
$80000
$075000
I4945
20
$100000
$06E000
I4946
21
$200000
$076000
I4947
22
$400000
$06F000
I4948
23
$800000
$077000
I4949
I24 contains the address of the DPRAM IC that is to be used for the automatic communications functions.
The value of I24 at power-up/reset sets the pointers for these automatic communications functions.
I4904 also contains information about the flash memory (this information is contained in I4909 as well).
Bits 0 – 2 of I4904, which contain a value from 0 to 7, report which type of flash-memory IC is present in
the system. Since bit 3 is not used, these bits form the last hex digit of I4909. The following list shows
what each value of this digit means:
0: Unknown flash IC (cannot save)
1: Intel 28F004S3 512k x 8 flash IC
2: Intel 28F008S3 1M x 8 flash IC (Opt 5x0)
3: Intel 28F016S3 2M x 8 flash IC (Opt 5x1,2)
4: Intel 28F160S3 2M x 8 flash IC (Opt 5x1,2)
5: Intel 28F320S3 4M x 8 flash IC (Opt 5x3)
6: Intel 28F320J5 4M x 8 flash IC (Opt 5x3)
7: Intel 28F640J5 8M x 8 flash IC