idt49c465apqfb Integrated Device Technology, idt49c465apqfb Datasheet - Page 12

• Manufacturer Part Number: idt49c465apqfb
• Description: 32-bit Flow-thru Error Detection Correction Unit
• Manufacturer: Integrated Device Technology

IDT49C465/A
32-BIT FLOW-THRU ERROR DETECTION AND CORRECTION UNIT
PARTIAL-WORD-WRITE OPERATIONS
FOR COMMON I/O MEMORIES:
complete word in question must be read from memory. This
must be done in order to correct any error which may have
occurred in the old word. Once the complete, corrected word
is available, with all the bytes verified, the new word may be
assembled in the byte mux and the new checkbits generated.
SD BUS
B
B
B
B
In order to perform a partial-word-write operation, the
3
2
1
0
= 1
= 1
= 1
= 0
BYTE 3
BYTE 2
BYTE 1
BYTE 0
CORRECTION
BLOCK
8
8
8
8
11.7
ing 3 bytes from an old word with a new lower order byte to
form a new word. The new word, along with the new checkbits,
may now be written to memory.
similar except that the new word is output on the SD Bus
instead of the MD Bus (refer to previous page).
The example shown above illustrates the case of combin-
In the separate I/O memory configuration, the situation is
B
B
B
B
A
A
A
A
BYTE
MUX
3
2
1
0
3
2
1
0
MILITARY AND COMMERCIAL TEMPERATURE RANGES
GENERATOR
CHECKBIT
IDT49C465
CBO
MD BUS
CBI
BYTE 3
BYTE 2
BYTE 1
BYTE 0
CHECKBIT
MEMORY
MEMORY
MAIN
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