NEC PD754144 - Manual (Page 52)

CHAPTER 3 FEATURES OF ARCHITECTURE AND MEMORY MAP
52 User’s Manual U10676EJ3V0UM
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Figure 3-7. µPD754244 I/O Map (1/8)
Hardware name (symbol)
Number of bits that
Bit
Address R/W
can be manipulated
manipulation Remarks
b3 b2 b1 b0 1-bit 4-bit 8-bit
addressing
F80H Stack pointer (SP) R/W – – – Bit 0 is fixed to 0.
F82H
Register bank selection register (RBS)
– – Note 1
Bank selection register (BS) R
F83H
Memory bank selection register (MBS)
–
F84H Stack bank selection register (SBS) R/W – – –
F85H Basic interval timer mode register (BTM) W – mem.bit Bit manipulation can be performed only on bit 3.
F86H Basic interval timer (BT) R – – –
F88H Modulo register for setting timer counter 2 R/W – – –
high-level period (TMOD2H)
F8AH Unmounted
F8BH WDTM Note 2 – – – W – – mem.bit
F8CH Unmounted
to
F8FH
Notes 1. Manipulation is possible separately with RBS and MBS in 4-bit manipulation. Manipulation is possible
with BS in 8-bit manipulation. Write data into MBS and RBS with the SEL MBn (n = 0, 4 or 15) and
SEL RBn (n = 0-3) instructions.
2. WDTM: Watchdog timer enable flag (W); Once set, cannot be cleared by an instruction.