FE9B: A5 3E

953

IOPRT

LDA

A2L

;SET RAM IN/OUT VECTORS

FE9D: 29 0F

954

 

AND

#$0F

 

 

FE9F: F0 06

955

 

BEQ

IOPRT1

 

 

FEA1: 09 C0

956

 

ORA

#IOADR/256

 

 

FEA3: A0 00

957

 

LDY

#$00

 

 

FEA5: F0 02

958

 

BEQ

IOPRT2

 

 

FEA7: A9 FD

959

IOPRT1

LDA

#COUT1/256

 

 

FEA9: 94 00

960

IOPRT2

STY

LOC0,X

 

 

FEAB: 95 01

961

 

STA

LOC1,X

 

 

FEAD: 60

962

 

RTS

 

 

 

FEAE: EA

963

 

NOP

 

 

 

FEAF: EA

964

 

NOP

 

 

 

FEB0: 4C 00 E0

965

XBASIC

JMP

BASIC

;TO BASIC WITH SCRATCH

FEB3: 4C 03 E0

966

BASCONT

JMP

BASIC2

;CONTINUE BASIC

FEB6: 20 75 FE

967

GO

JSR

A1PC

;ADR TO PC IF SPEC'D

FEB9: 20 3F FF

968

 

JSR

RESTORE

;RESTORE META REGS

FEBC: 6C 3A 00

969

 

JMP

(PCL)

;GO TO USER SUBR

FEBF: 4C D7 FA

970

REGZ

JMP

REGDSP

;TO REG DISPLAY

FEC2: C6 34

971

TRACE

DEC

YSAV

 

 

FEC4: 20 75 FE

972

STEPZ

JSR

A1PC

;ADR TO PC IF SPEC'D

FEC7: 4C 43 FA

973

 

JMP

STEP

;TAKE ONE STEP

FECA: 4C F8 03

974

USR

JMP

USRADR

;TO USR SUBR AT USRADR

FECD: A9 40

975

WRITE

LDA

#$40

 

 

FECF: 20 C9 FC

976

 

JSR

HEADR

;WRITE 10-SEC HEADER

FED2: A0 27

977

 

LDY

#$27

 

 

FED4: A2 00

978

WR1

LDX

#$00

 

 

FED6: 41 3C

979

 

EOR

(A1L,X)

 

 

FED8: 48

980

 

PHA

 

 

 

FED9: A1 3C

981

 

LDA

(A1L,X)

 

 

FEDB: 20 ED FE

982

 

JSR

WRBYTE

 

 

FEDE: 20 BA FC

983

 

JSR

NXTA1

 

 

FEE1: A0 1D

984

 

LDY

#$1D

 

 

FEE3: 68

985

 

PLA

 

 

 

FEE4: 90 EE

986

 

BCC

WR1

 

 

FEE6: A0 22

987

 

LDY

#$22

 

 

FEE8: 20 ED FE

988

 

JSR

WRBYTE

 

 

FEEB: F0 4D

989

 

BEQ

BELL

 

 

FEED: A2 10

990

WRBYTE

LDX

#$10

 

 

FEEF: 0A

991

WRBYT2

ASL

 

 

 

FEF0: 20 D6 FC

992

 

JSR

WRBIT

 

 

FEF3: D0 FA

993

 

BNE

WRBYT2

 

 

FEF5: 60

994

 

RTS

 

 

 

FEF6: 20 00 FE

995

CRMON

JSR

BL1

;HANDLE A CR AS BLANK

FEF9: 68

996

 

PLA

 

;

THEN POP STACK

FEFA: 68

997

 

PLA

 

;

AND RTN TO MON

FEFB: D0 6C

998

 

BNE

MONZ

 

 

FEFD: 20 FA FC

999

READ

JSR

RD2BIT

;FIND TAPEIN EDGE

FF00: A9 16

1000

 

LDA

#$16

 

 

FF02: 20 C9 FC

1001

 

JSR

HEADR

;DELAY 3.5 SECONDS

FF05: 85 2E

1002

 

STA

CHKSUM

;INIT CHKSUM=$FF

FF07: 20 FA FC

1003

 

JSR

RD2BIT

;FIND TAPEIN EDGE

FF0A: A0 24

1004 RD2

LDY

#$24

;LOOK FOR SYNC BIT

FF0C: 20 FD FC

1005

 

JSR

RDBIT

;

(SHORT 0)

FF0F: B0 F9

1006

 

BCS

RD2

;

LOOP UNTIL FOUND

FF11: 20 FD FC

1007

 

JSR

RDBIT

;SKIP SECOND SYNC H-CYCLE

FF14: A0 3B

1008

 

LDY

#$3B

;INDEX FOR 0/1 TEST

FF16: 20 EC FC

1009 RD3

JSR

RDBYTE

;READ A BYTE

FF19: 81 3C

1010

 

STA

(A1L,X)

;STORE AT (A1)

FF1B: 45 2E

1011

 

EOR

CHKSUM

 

 

FF1D: 85 2E

1012

 

STA

CHKSUM

;UPDATE RUNNING CHKSUM

FF1F: 20 BA FC

1013

 

JSR

NXTA1

;INC A1, COMPARE TO A2

FF22: A0 35

1014

 

LDY

#$35

;COMPENSATE 0/1 INDEX

 

 

 

 

 

 

 

Page 34 Page 36
Page 35
Image 35
Apple II manual Ioprt LDA A2L SET RAM IN/OUT Vectors
Page 34 Page 36

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.
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