Motorola MC68340 User Manual page 216

Register Field:
The system control register is specified by the register field (see Table 5-24). The FAR
is a read-only register—any write to it is ignored.
5.6.2.8.8 Read Memory Location (READ). Read the sized data at the memory location
specified by the long-word address. Only absolute addressing is supported. The SFC
register determines the address space accessed. Valid data sizes include byte, word, or
long word.
Command Format:
15 14 13 12
0 0 0 1
Command Sequence:
READ (B/W)
???
READ (LONG)
??? "NOT READY"
Operand Data:
The single operand is the long-word address of the requested memory location.
Result Data:
The requested data is returned as either a word or long word. Byte data is returned in
the least significant byte of a word result, with the upper byte cleared. Word results
return 16 bits of significant data; long-word results return 32 bits.
A successful read operation returns data bit 16 cleared. If a bus or address error is
encountered, the returned data is $10001.
5.6.2.8.9 Write Memory Location (WRITE). Write the operand data to the memory
location specified by the long-word address. The DFC register determines the address
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11 10 9 8
1 0 0 1
MS ADDR LS ADDR
"NOT READY" "NOT READY"
XXX NEXT CMD
"NOT READY"
"ILLEGAL"
MS ADDR LS ADDR
"NOT READY"
XXX NEXT CMD
"ILLEGAL" "NOT READY"
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7 6 5 4
OP SIZE 0 0
READ
XXX
MEMORY
"NOT READY"
LOCATION
NEXT CMD
RESULT
XXX
BERR/AERR
READ
XXX
MEMORY
"NOT READY"
LOCATION
XXX
MS RESULT
XXX
BERR/AERR
3 2 1 0
0 0 0 0
NEXT CMD
"NOT READY"
NEXT CMD
LS RESULT
NEXT CMD
"NOT READY"
5- 79