0427

8291

18

 

 

 

CLC

 

 

0428

8292

60

 

 

M29

RTS

 

 

0429

8293

EE 4A A6

INCP3

INC P3L

;INCREMENT P3 (16 BITS)

0430

8296

D0

03

 

 

BNE

*+5

 

0431

8298

EE 4B A6

 

INC

P3H

 

0432

829B

60

 

 

 

RTS

 

 

0433

829C

AE 4D A6

P2SCR

LDX P2H

;MOVE P2 TO FE,FF

0434

829F

86

FF

 

 

STX

$FF

 

0435

82A1

AE 4C A6

 

LDX

P2L

 

0436

82A4

86

FE

 

 

STX

$FE

 

0437

82A6

60

 

 

 

RTS

 

 

0438

82A7

AE 4B A6

P3SCR

LDX P3H

;MOVE P3 TO FE,FF

0439

82AA 86 FF

 

 

STX

$FF

 

0440

82AC AE 4A A6

 

LDX

P3L

 

0441

82AF 86 FE

 

 

STX

$FE

 

0442

82B1

60

 

 

 

RTS

 

 

0443

82B2

E6

FE

 

INCCMP INC $FE

;INCREM FE,FF, COMPARE TO P3

0444

82B4

D0

14

 

 

BNE

COMPAR

 

0445

82B6

E6

FF

 

 

INC

$FF

 

0446

82B8

D0

10

 

WRAP

BNE

COMPAR

;TEST TO WRAP AROUND

0447

82BA 2C BD 82

 

BIT

EXWRAP

 

0448

82BD 60

 

 

EXWRAP RTS

 

 

0449

82BE A5 FE

 

DECCMP LDA $FE

;DECREM FE,FF AND COMPARE TO P3

0450

82C0

D0

06

 

 

BNE

M32

 

0451

82C2

A5

FF

 

 

LDA

$FF

 

0452

82C4

F0

F2

 

 

BEQ

WRAP

 

0453

82C6

C6

FF

 

 

DEC

$FF

 

0454

82C8

C6

FE

 

M32

DEC

$FE

 

0455

82CA 20 88 81

COMPAR JSR

SAVER

;COMPARE FE,FF TO P3

0456

82CD A5 FF

 

 

LDA

$FF

 

0457

82CF CD 4B A6

 

CMP

P3H

 

0458

82D2

D0

05

 

 

BNE

EXITCP

 

0459

82D4

A5

FE

 

 

LDA

$FE

 

0460

82D6

CD 4A A6

 

CMP

P3L

 

0461

82D9

B8

 

 

EXITCP CLV

 

 

0462

82DA 4C BE 81

 

JMP

RESXF

 

0463

82DD 08

 

 

CHKSAD PHP

 

;16 BIT CKSUM IN SCR6,7

0464

82DE 48

 

 

 

PHA

 

 

0465

82DF 18

 

 

 

CLC

 

 

0466

82E0

6D

36

A6

 

ADC

SCR6

 

0467

82E3

8D

36

A6

 

STA

SCR6

 

0468

82E6

90

03

 

 

BCC

M33

 

0469

82E8

EE 37 A6

 

INC

SCR7

 

0470

82EB 68

 

 

M33

PLA

 

 

0471

82EC 28

 

 

 

PLP

 

 

0472

82ED 60

 

 

 

RTS

 

 

0473

82EE AD 59 A6

OUTPC

LDA PCLR

;OUTPUT PC

0474

82F1

AE 5A A6

 

LDX

PCHR

 

0475

82F4

48

 

 

OUTXAH PHA

 

 

0476

82F5

8A

 

 

 

TXA

 

 

0477

82F6

20

FA 82

 

JSR

OUTBYT

 

0478

82F9

68

 

 

 

PLA

 

 

0479

82FA 48

 

 

OUTBYT PHA

 

;OUTPUT 2 HEX DIGS FROM A

0480

82FB 48

 

 

 

PHA

 

 

0481

82FC 4A

 

 

 

LSR

A

 

0482

82FD 4A

 

 

 

LSR

A

 

0483

82FE 4A

 

 

 

LSR

A

 

0484

82FF 4A

 

 

 

LSR

A

 

0485

8300

20

44

8A

 

JSR

NBASOC

 

0486

8303

68

 

 

 

PLA

 

 

0487

8304

20

44

8A

 

JSR

NBASOC

 

0488

8307

68

 

 

 

PLA

 

 

 

 

 

 

 

 

 

 

 

Page 109
Image 109
Apple II manual Exwrap RTS, Chksad PHP, Outxah PHA, Txa, Outbyt PHA

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.