21285-AB

Manufacturer Part Number21285-AB
DescriptionMicroprocessor, 21285 Core Logic For SA-110 Microprocessor
ManufacturerIntel Corporation
21285-AB datasheet
 

Specifications of 21285-AB

CaseBGADc99+/00+
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Page 108/159:

Doorbell Register Offset

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Registers
7.2.6
Doorbell Register—Offset 60h
Each bit in the doorbell register is write-1-to-set from the SA-110, write-1-to-clear from the PCI
bus.
Dword Bit
Name
31:0
Software
interrupt
7.2.7
Doorbell Setup—Offset 64h
Doorbell setup is an alias of the doorbell register to allow for initialization and test. It is a
read/write register.
To initialize the doorbells:
1. Write doorbell PCI mask register (see
SA-110-to-PCI notification.
2. Write doorbell SA-110 mask register (see
PCI-to-SA-110 notification.
3. Write doorbell setup register such that all bit positions used for SA-110-to-PCI notification are
written with 0, and all bit positions used for PCI-to-SA-110 notification are written with 1.
Unused bits can be written to either value.
Dword Bit
Name
31:0
Read/write data
address
7.2.8
ROM Write Byte Address Register—Offset 68h
The ROM write byte address register is used to supply the two low-order bits of the ROM address
during write cycles.
Dword Bit
Name
1:0
ROM address
31:2
7-18
R/W
Description
R/W1S from
Causes a software interrupt from the
SA-110 and R/
processor, or from the host processor to SA-110.
W1C from PCI
Reset value: Contents are undefined.
Section
7.3.26) with a 1 in all bit positions used for
Section
7.3.27) with a 1 in all bit positions used for
R/W
Description
R/W
Writes to this address; place data directly into the doorbell
register.
Reads to this address; read the value in the doorbell
register.
R/W
Description
R/W
Supplies the two low-order bits of the ROM address during
write cycles. It must be controlled by software during
writes to byte or word wide ROMs, since neither the
SA-110 or PCI can put the data on the low-byte lane(s)
and simultaneously place the correct byte (word) address
on the two low-order address bits.
Reset value: Undefined.
R
Read only as 0.
21285 Core Logic for SA-110 Datasheet
SA-110 to host