User guide

10.1.1.1 Address Modifier
The scatter-gather entry has two fields that provide the address modifier used
in the master VMEbus transfer. The address size (ASIZ) and function code (FC)
fields map directly to the VME interface controller’s input for ASIZ and FC.
Table 10–1 shows the use of these fields.
Table 10–1 Formation of Address Modifier Codes from Scatter-Gather Entry
ASIZ1/0 FC2/1 Block Mode Operation AM<5:0>
01
(A32)
00 No User Data 09h
01 No User Program 0Ah
10 No Supervisory Data 0Dh
11 No Supervisory Program 0Eh
0x Yes User Page 0Bh (D64 08h)
1x Yes Supervisory Page 0Fh (D64 0Ch)
11 (A24) 00 No User Data 39h
01 No User Program 3Ah
10 No Supervisory Data 3Dh
11 No Supervisory Program 3Eh
0x Yes User Page 3Bh (D64 38h)
1x Yes Supervisory Page 3Fh (D64 3Ch)
10
(A16)
0x No User Access 29h
1x No Supervisory Access 2Dh
00 User Defined AM codes VIC_AMSR
10.1.1.2 Read-Modify-Write
When a scatter-gather entry’s read-modify-write (RMW) bit is set, any master
access to that page causes the VME interface to perform the next two accesses as
a single sequence of VMEbus cycles. The two accesses are:
• The one whose scatter-gather entry has RMW bit set
• The next PCI cycle that addresses the VMEbus
10–6 VME Interface