Hardware Initialization States

Table 3–2. State of the Status Register (17 bit) after RESET Low-to-High (Bits 5 through 16 are left uninitialized)

Bit

Bit Name

Initialized Value

Description

 

 

 

 

0

XM

0

Extended sign mode disabled

 

 

 

 

1

UM

0

Unsigned multiplier mode disabled (allows signed multiplier mode)

 

 

 

 

2

OM

0

Overflow mode disabled (allows ALU normal mode)

 

 

 

 

3

FM

0

Shift mode for fractional multiplication disabled (allows unsigned

fractional/integer arithmetic)

 

 

 

 

 

 

 

4

IM

0

Global interrupt enable bit

 

 

 

 

5

(reserved)

 

Reserved for future use

 

 

 

 

6

XZF

 

Transfer equal-to-zero status bit

 

 

 

 

7

XSF

 

Transfer sign status bit

 

 

 

 

8

RCF

 

Auxiliary register carry-out status bit

 

 

 

 

9

RZF

 

Auxiliary register equal-to-zero status bit

 

 

 

 

10

OF

Same state as

Accumulator overflow status bit

 

 

 

11

SF

before RESET

Accumulator sign status bit (extended 17th bit)

 

 

 

 

 

12

ZF

 

Accumulator equal-to-zero status bit (16 bits)

 

 

 

 

13

CF

 

Accumulator carry-out status bit (16th ALU bit)

 

 

 

 

14

TF1

 

Test flag 1

 

 

 

 

15

TF2

 

Test flag 2

 

 

 

 

16

TAG

 

Memory tag

 

 

 

 

3-22

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Image 86
Texas Instruments MSP50C6xx manual Bit Bit Name Initialized Value Description