PPC7A Product Manual
Configuration
4-4
1
st
Edition
ECC Enable Link (E6)
This link enables or disables ECC on the SDRAM, as follows:
S
ETTING
F
UNCTION
In
Enables ECC
Out (default)
Disables ECC
FLASH Boot Image Select Link (E7 & E8)
The System FLASH is divided into four sections, with all sections accessible all the time. Using these
links, the four sections can be swapped around in the memory map. This allows for two (three if the data
area is not required) boot images to be blown into the FLASH, a Factory blown Boot recovery image,
with the links selecting which image is used at boot time. The state of the links is reflected in the
Memory Configuration Register (Port 0x0804)
- see Chapter 8. Normally, these links are not fitted and
the PPC7A boots from the default boot area from FLASH (see Chapter 8 for details of FLASH
operation). However, when either of the links are fitted, the PPC7A boots from the alternate boot image.
After boot time, the link setting can be software-overridden to select the different images.
E7
E8
F
UNCTION
Out (default) Out (default)
Normal FLASH boot image operation
Out
In
Alternate FLASH boot image
In
Out
Recovery Boot image
In
In
2nd Alternate FLASH boot image (Data area)
On-board SCSI Terminator Enable Link (E13)
This link enables or disables the on-board SCSI terminators, as follows:
S
ETTING
F
UNCTION
In
Enable on-board SCSI terminators
Out (default)
Disable on-board SCSI terminators
If you are using the SCSI bus, you are recommended to locate the PPC7A at one end and enable the
terminator by fitting link E13. If you want to use the PPC7A somewhere other than at the end of the
SCSI bus, ensure that E13 is not fitted.
$
Note:
Fitting E13 when the PPC7A is not located at the end of a SCSI bus may cause erroneous SCSI
operation.
This link can be overridden by a control register.
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