NEC UPD789026 Series User Manual page 98

(2) Port mode register 5 (PM5)
This register sets the input/output of port 5 in 1-bit units.
To use the P51/TO2 pin for timer output, set the output latch of PM51 and P51 to 0.
PM5 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets PM5 to FFH.
7
Symbol
PM5 1
PM51
0 Output mode (output buffer on)
1 Input mode (output buffer off)
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98
CHAPTER 6 16-BIT TIMER
Figure 6-3. Port Mode Register 5 Format
6 5 4
1 1 1 PM53
User's Manual U11919EJ3V0UM00
3 2 1
PM52 PM51 PM50
P51 Pin Input/Output Selection
0
Address After Reset
FF25H FFH
R/W
R/W