*WHEN THE NUMBER IS LESS THAN 2**(-128).

*EXPONENT: THE EXPONENT REPRESENTS POWERS OF TWO. THE

*REPRESENTATION IS 2'S COMPLIMENT EXCEPT THAT THE SIGN

*BIT (BIT 7) IS COMPLIMENTED. THIS ALLOWS DIRECT COMPARISON

*OF EXPONENTS FOR SIZE SINCE THEY ARE STORED IN INCREASING

*NUMERICAL SEQUENCE RANGING FROM $00 (-128) TO $FF (+127)

*($ MEANS NUMBER IS HEXADECIMAL).

*

*REPRESENTATION OF DECIMAL NUMBERS: THE PRESENT FLOATING

*POINT REPRESENTATION ALLOWS DECIMAL NUMBERS IN THE APPROXIMATE

*RANGE OF 10**(-38) THROUGH 10**(38) WITH 6 TO 7 SIGNIFICANT

*DIGITS.

 

 

 

 

*

 

 

0003

 

 

 

*

ORG 3

SET BASE PAGE ADRESSES

 

 

 

 

0003

EA

 

 

SIGN

NOP

 

0004

EA

 

 

X2

NOP

EXPONENT 2

0005

00

00

00

M2

BSS 3

MANTISSA 2

0008

EA

 

 

X1

NOP

EXPONENT 1

0009

00

00

00

M1

BSS 3

MANTISSA 1

000C

 

 

 

E

BSS 4

SCRATCH

0010

 

 

 

Z

BSS 4

 

0014

 

 

 

T

BSS 4

 

0018

 

 

 

SEXP

BSS 4

 

001C

00

 

 

INT

BSS 1

 

1D00

 

 

 

*

ORG $1D00

STARTING LOCATION FOR LOG

 

 

 

 

 

 

 

 

*

 

 

 

 

 

 

*

 

 

 

 

 

 

*

NATURAL LOG OF MANT/EXP1 WITH RESULT IN MANT/EXP1

 

 

 

 

*

 

 

1D00

A5

09

 

LOG

LDA M1

 

1D02

F0

02

 

 

BEQ ERROR

 

1D04

10

01

 

 

BPL CONT

IF ARG>0 OK

1D06

00

 

 

ERROR

BRK

ERROR ARG<=0

 

 

 

 

*

 

 

1D07

20

1C

1F

CONT

JSR SWAP

MOVE ARG TO EXP/MANT2

1D0A

A5

04

 

 

LDA X2

HOLD EXPONENT

1D0C

A0

80

 

 

LDY =$80

 

1D0E

84

04

 

 

STY X2

SET EXPONENT 2 TO 0 ($80)

1D10

49

80

 

 

EOR =$80

COMPLIMENT SIGN BIT OF ORIGINAL EXPONENT

1D12

85

0A

 

 

STA M1+1

SET EXPONENT INTO MANTISSA 1 FOR FLOAT

1D14

A9

00

 

 

LDA =0

 

1D16

85

09

 

 

STA M1

CLEAR MSB OF MANTISSA 1

1D18

20

2C

1F

 

JSR FLOAT

CONVERT TO FLOATING POINT

1D1B

A2

03

 

 

LDX =3

4 BYTE TRANSFERS

1D1D

B5

04

 

SEXP1

LDA X2,X

 

1D1F

95

10

 

 

STA Z,X

COPY MANTISSA TO Z

1D21

B5

08

 

 

LDA X1,X

 

1D23

95

18

 

 

STA SEXP,X

SAVE EXPONENT IN SEXP

1D25

BD D1 1D

 

LDA R22,X

LOAD EXP/MANT1 WITH SQRT(2)

1D28

95

08

 

 

STA X1,X

 

1D2A

CA

 

 

 

DEX

 

1D2B

10

F0

 

 

BPL SEXP1

 

1D2D

20

4A

1F

 

JSR FSUB

Z-SQRT(2)

1D30

A2

03

 

 

LDX =3

4 BYTE TRANSFER

1D32

B5

08

 

SAVET

LDA X1,X

SAVE EXP/MANT1 AS T

1D34

95

14

 

 

STA T,X

 

1D36

B5

10

 

 

LDA Z,X

LOAD EXP/MANT1 WITH Z

1D38

95

08

 

 

STA X1,X

 

1D3A

BD D1 1D

 

LDA R22,X

LOAD EXP/MANT2 WITH SQRT(2)

 

 

 

 

 

 

 

Page 83
Image 83
Apple II manual ORG SET Base page Adresses

II specifications

The Apple II, launched in April 1977, was one of the first highly successful mass-produced microcomputer products. It marked a significant leap in personal computing, setting standards for future developments in the industry. Created by Steve Wozniak and Steve Jobs, the Apple II differentiated itself with its user-friendly design, appealing aesthetics, and robust capabilities.

One of the standout features of the Apple II was its open architecture, which allowed users to expand and enhance the computer's functionality. This design enabled hundreds of third-party hardware and software developers to contribute to its ecosystem, resulting in an array of peripherals, including printers, modems, and storage devices. The Apple II utilized a MOS Technology 6502 microprocessor running at a clock speed of 1 MHz. Initially equipped with 4 KB of RAM, the machine could be expanded to 48 KB, accommodating more complex applications and programs.

The Apple II was also notable for its colorful graphics. It was one of the first computers to support color display, offering a 6-color palette with a resolution of 280x192 pixels in 16 colors when using its Color Graphics Card. This feature significantly enhanced the visual appeal of games and educational software developed for the platform, making computing more accessible and entertaining for various audiences.

Apple's commitment to user experience was evident in the design of the machine. It featured an integrated keyboard and a plastic case, which was both durable and visually appealing. The self-contained design included drive bays for floppy disk drives, allowing for quicker data access than traditional tape drives. It also supported audio output, enabling sound effects and music, a novelty at the time.

The introduction of the Apple DOS operating system further underscored the machine's capabilities. DOS streamlined file management and made it easier for users to navigate and manage their data. The combination of hardware and software positioned the Apple II as an educational tool and a gaming platform, fostering a vibrant software ecosystem.

The Apple II family continued to evolve, with variations like the Apple II+, IIe, and IIgs being introduced over the years. These iterations brought enhancements in memory, processing power, and graphics capabilities. The legacy of the Apple II endures, not only as a foundational product in personal computing but also as a symbol of innovation that paved the way for future advancements in technology. Its impact is still felt today, as it inspired countless developers and shaped the trajectory of the computer industry.