
Chapter 2 Hardware Essentials
Address Buffer Port | Page 2 - 9 |
Control Field
Use this
With it, you can
•Transfer data in
•Byte or word swap command structures to be compatible with the byte and word ordering of either Intel or Motorola architectures.
Note
For any of the control bits to be considered valid by the adapter, the SET bit must be one.
Note
The RF3880 supports
Byte and word swapping are further discussed in Chapter 8, Details of Usage.
The bit meanings of the Control Field are as follows:
7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
SET | 0 | 0 | 0 | 0 | WID | WSC | BSC |
Table 7: Control Field of Address Buffer Port
BSC Byte Swapping Control - Defines whether high and low bytes of a word will be swapped during transfer of status and parameter blocks.
0 ⇒ No swapping.
1 ⇒ Change byte order.
WSC Word Swapping Control - Defines whether high and low words of a double word will be swapped during transfer of status and parameter blocks.
0 ⇒ No swapping.
1 ⇒ Change word order.
WID WIDth of data transfers - Determines (in conjunction with VMEbus Address Modifier) the width of data transfers across the system bus.
0
(forces
1
SET select new control SETtings - Determines whether the rest of the bits in the Control Field should be applied to adapter operation.
0 ⇒ ignore all other bits.
1 ⇒ apply bit values to next transfer.
User’s Guide | 21020285 D |