164
Am79C976
8/01/00
P R E L I M I N A R Y
PMAT0: OnNow Pattern Register 0
Offset 190h
This register is used to control and indirectly access the
Pattern Match RAM (PMR). When the PMAT_MODE
bit (CMD7, bit3) is 1, Pattern Match logic is enabled. No
bus accesses into PMR are possible, and PMAT0 and
PMAT1 are ignored. When PMAT_MODE is set, a read
of PMAT0 or PMAT1 returns all undefined bits.
When the PMAT_MODE bit (CMD7, bit3) is 0, the Pat-
tern Match logic is disabled and accesses to the PMR
are possible. Bits 6-0 of PMAT0 specify the address of
the PMR word to be accessed. Following the write to
PMAT0, the PMR word may be read by reading PMAT1
and the high order bytes of PMAT0 in any order. To
write to PMR word, the write to PMAT0 must be fol-
lowed by a write to PMAT1 to complete the operation.
The RAM will not actually be written until the write to
PMAT1 is complete. The write to PMAT1 causes all 5
bytes (two bytes of PMAT1 and the upper three bytes of
PMAT0) to be written to whatever PMR word is ad-
dressed by bits 6:0 of PMAT0.
The contents of this register are cleared to 0 when the
RST pin is asserted. The register is not cleared at the
start of a serial EEPROM read operation or after a se-
rial EEPROM read error.
Table 70. PMAT0: OnNow Pattern Register 0
0#80
Offset 194h
This register is used to control and indirectly access the
Pattern Match RAM (PMR). When the PMAT_MODE
bit (CMD7, bit3) is 1, Pattern Match logic is enabled. No
bus accesses into PMR are possible, and PMAT0 and
PMAT1 are ignored. When PMAT_MODE is set, a read
of PMAT0 or PMAT1 returns all undefined bits.
When the PMAT_MODE bit (CMD7, bit3) is 0, the Pat-
tern Match logic is disabled and accesses to the PMR
are possible. Bits 6-0 of PMAT0 specify the address of
the PMR word to be accessed. Following the write to
PMAT0, the PMR word may be read by reading PMAT1
and the high order bytes of PMAT0 in any order. To
write to PMR word, the write to PMAT0 must be fol-
lowed by a write to PMAT1 to complete the operation.
The RAM will not actually be written until the write to
PMAT1 is complete. The write to PMAT1 causes all
5 bytes (two bytes of PMAT1 and the upper three bytes
of PMAT0) to be written to whatever PMR word is ad-
dressed by bits 6:0 of PMAT0.
The contents of this register are cleared to 0 when the
RST pin is asserted. The register is not cleared at the
start of a serial EEPROM read operation or after a se-
rial EEPROM read error.
Table 71. PMAT1: OnNow Pattern Register 1
Bit
Name
Description
31-24
PMR_B2
Pattern Match RAM Byte 2. This byte is written into or read from Byte 2 of the Pattern Match RAM.
This field is an alias of BCR46, bits [15:8].
23-16
PMR_B1
Pattern Match RAM Byte 1. This byte is written into or read from Byte 1 of the Pattern Match RAM.
This field is an alias of BCR46, bits [7:0].
15-8
PMR_B0
Pattern Match RAM Byte 0. This byte is written into or read from Byte 0 of the Pattern Match RAM.
This field is an alias of BCR45, bits [15:8].
7
RES
Reserved location. Written as zero and read as undefined.
6-0
PMR_ADDR
Pattern Match RAM Address. These bits are the Pattern Match RAM address to be written to or
read from.
Bit
Name
Description
15-8
PMR_B4
Pattern Match RAM Byte 4. This byte is written into or read from Byte 4 of the Pattern Match RAM.
This field is an alias of BCR47, bits [15:8].
7-0
PMR_B3
Pattern Match RAM Byte 3. This byte is written into or read from Byte 3 of the Pattern Match RAM.
This field is an alias of BCR47, bits [7:0].