UPD780138 Datasheet, PDF (353/558 Pages) NEC – 8-Bit Single-Chip Microcontrollers

CHAPTER 16 MULTIPLIER/DIVIDER
(1) Remainder data register 0 (SDR0)
SDR0 is a 16-bit register that stores a remainder. This register stores 0 in the multiplication mode and the
remainder of an operation result in the division mode.
This register can be read by an 8-bit or 16-bit memory manipulation instruction.
RESET input clears this register to 0000H.
Figure 16-2. Format of Remainder Data Register 0 (SDR0)
Address: FF60H, FF61H After reset: 0000H R
Symbol
FF61H (SDR0H)
FF60H (SDR0L)
SDR0
SDR SDR SDR SDR SDR SDR SDR SDR SDR SDR SDR SDR SDR SDR SDR SDR
015 014 013 012 011 010 009 008 007 006 005 004 003 002 001 000
Cautions 1. The value read from SDR0 during operation processing (while bit 7 (DMUE) of
multiplier/divider control register 0 (DMUC0) is 1) is not guaranteed.
2. SDR0 is reset when the operation is started (when DMUE is set to 1).
(2) Multiplication/division data register A0 (MDA0H, MDA0L)
MDA0 is a 32-bit register that sets a 16-bit multiplier A in the multiplication mode and a 32-bit dividend in the
division mode, and stores the 32-bit result of the operation (higher 16 bits: MDA0H, lower 16 bits: MDA0L).
Figure 16-3. Format of Multiplication/Division Data Register A0 (MDA0H, MDA0L)
Address: FF62H, FF63H, FF64H, FF65H After reset: 0000H, 0000H R/W
Symbol
FF65H (MDA0HH)
FF64H (MDA0HL)
MDA0H MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA
031 030 029 028 027 026 025 024 023 022 021 020 019 018 017 016
Symbol
FF63H (MDA0LH)
FF62H (MDA0LL)
MDA0L MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA MDA
015 014 013 012 011 010 009 008 007 006 005 004 003 002 001 000
Cautions 1. MDA0H is cleared to 0 when an operation is started in the multiplication mode (when
multiplier/divider control register 0 (DMUC0) is set to 81H).
2. Do not change the value of MDA0 during operation processing (while bit 7 (DMUE) of
multiplier/divider control register 0 (DMUC0) is 1). Even in this case, the operation is
executed, but the result is undefined.
3. The value read from MDA0 during operation processing (while DMUE is 1) is not
guaranteed.
User’s Manual U16228EJ2V0UD
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