Cycle Acknowledgment; Cycle Request; Pci Cack Cycle Codes; Pci Creq Cycle Codes - Digital Equipment Digital AlphaStation 200 Series Technical Information

Cycle Acknowledgment

The cAck_h lines connecting to the CPU signal cycle codes for completions of cycle
transactions. Table 9-2 shows the cAck cycle code types.
Table 9-2. PCI cAck Cycle Codes
Code Cycle Type
000 IDLE
001 HARD_ERROR
010 SOFT_ERROR - . This code is not
used.
011 STL_C FAIL or STQ_C FAIL
100 OK
101 Undefined
110 Undefined
111 Undefined

Cycle Request

The cReq lines are used to indicate the cycle type at the start of an external cycle. Table
9-3 shows the cReq cycle code types.
Table 9-3. PCI cReq Cycle Codes
Code Cycle Type
000 IDLE
001 BARRIER
010 FETCH
011 FETCH_M
100 READ_BLOCK
101 WRITE_BLOCK
110 LDL_L or LDQ_L
111 STL_C or STQ_C
Fault Management
9-3