UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 772

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

770
(3) Multiplication/division data register B0 (MDB0)
Address: FF66H, FF67H
Symbol
MDB0
Cautions 1. Do not change the value of MDB0 during operation processing (while bit 7 (DMUE) of
The functions of MDA0 when an operation is executed are shown in the table below.
The register configuration differs between when multiplication is executed and when division is executed, as
follows.
MDA0 fetches the calculation result as soon as the clock is input, when bit 7 (DMUE) of multiplier/divider
control register 0 (DMUC0) is set to 1.
MDA0H and MDA0L can be set by an 8-bit or 16-bit memory manipulation instruction.
Reset signal generation clears MDA0H and MDA0L to 0000H.
MDB0 is a register that stores a 16-bit multiplier B in the multiplication mode and a 16-bit divisor in the
division mode.
MDB0 can be set by an 8-bit or 16-bit memory manipulation instruction.
Reset signal generation clears MDB0 to 0000H.
DMUSEL0
Register configuration during multiplication
MDA0 (bits 15 to 0)
Register configuration during division
MDA0 (bits 31 to 0)
0
1
<Multiplier A>
<Dividend>
MDB
015
2. Do not clear MDB0 to 0000H in the division mode. If set, undefined operation results are
Figure 22-4. Format of Multiplication/Division Data Register B0 (MDB0)
multiplier/divider control register 0 (DMUC0) is 1). Even in this case, the operation is
executed, but the result is undefined.
stored in MDA0 and SDR0.
MDB
014
Division mode
Multiplication mode
Table 22-2. Functions of MDA0 During Operation Execution
MDB
013
Operation Mode
After reset: 0000H
MDB0 (bits 15 to 0) = MDA0 (bits 31 to 0)
MDB0 (bits 15 to 0) = MDA0 (bits 31 to 0) … SDR0 (bits 15 to 0)
FF67H (MDB0H)
<Multiplier B>
MDB
<Divisor>
012
CHAPTER 22 MULTIPLIER/DIVIDER
Preliminary User’s Manual U19748EJ1V0UD
MDB
011
MDB
010
R/W
MDB
009
Dividend
Higher 16 bits: 0, Lower 16
bits: Multiplier A
<Product>
<Quotient>
MDB
008
Setting
MDB
007
MDB
006
<Remainder>
MDB
005
FF66H (MDB0L)
Division result (quotient)
Multiplication result
(product)
MDB
004
Operation Result
MDB
003
MDB
002
MDB
001
MDB
000