Maxim Integrated MAXQ7666 - Manual (Page 54)

1.4.11 Prefix Register (PFX[n])
Register Description: Prefix Register
Register Name: PFX[n]
Register Address: Module 0Bh, Index 0nh
Bits 15 to 0: Prefix Register Bits 15 to 0 (PFX[n].15 to PFX[n].0). The prefix register provides a means of supplying an additional 8
bits of high-order data for use by the succeeding instruction as well as providing additional indexing capabilities. This register will only
hold any data written to it for one execution cycle, after which it will revert to 0000h. Although this is a 16-bit register, only the lower 8
bits are actually used for prefixing purposes by the next instruction. Writing to or reading from any index in the Prefix module will select
the same 16-bit register. However, when the prefix register is written, the index n used for the PFX[n] write also determines the high-
order bits for the register source and destination specified in the following instruction.
The index selection reverts to 0 (default mode allowing selection of registers 0h to 7h for destinations) after one cycle in the same man-
ner as the contents of the prefix register.
MAXQ7665/MAXQ7666 User’s Guide
1-52
Bit # 15 14 13 12 11 10 9 8
Name PFX[n].15 PFX[n].14 PFX[n].13 PFX[n].12 PFX[n].11 PFX[n].10 PFX[n].9 PFX[n].8
Reset 0 0 0 0 0 0 0 0
Access rw rw rw rw rw rw rw rw
Bit # 7 6 5 4 3 2 1 0
Name PFX[n].7 PFX[n].6 PFX[n].5 PFX[n].4 PFX[n].3 PFX[n].2 PFX[n].1 PFX[n].0
Reset 0 0 0 0 0 0 0 0
Access rw rw rw rw rw rw rw rw
r = read, w = write
Note: This register is cleared to 0000h on all forms of reset.
SOURCE, DESTINATION INDEX SELECTION
WRITE TO
SOURCE REGISTER RANGE DESTINATION REGISTER RANGE
PFX[0] 0h to Fh 0h to 7h
PFX[1] 10h to 1Fh 0h to 7h
PFX[2] 0h to Fh 8h to Fh
PFX[3] 10h to 1Fh 8h to Fh
PFX[4] 0h to Fh 10h to 17h
PFX[5] 10h to 1Fh 10h to 17h
PFX[6] 0h to Fh 18h to 1Fh
PFX[7] 10h to 1Fh 18h to 1Fh
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