3787

FCC3 D0 06

 

BNE

OPCOMP

 

3788

FCC5 20 94 E3

ERRORM JSR

CKER00

;OUTPUT ERROR MESSAGE

3789

FCC8 4C AA FB

 

JMP

STARTM

 

3790

FCCB

 

 

 

 

3791

FCCB

;COMPUTE FINAL OP CODE FOR DEFINED ADDRESING MODE

3792

FCCB BD E2 FA

OPCOMP LDA TYPTR1,X

;MATCH TYPE MASK WITH VALID MODE

3793

FCCE F0 05

 

BEQ OPCMP1

;PATTERNS & SKIP 1ST WORD TEST IF

3794

FCD0 2D 26 01

 

AND TMASK1

;ALREADY ZERO

3795

FCD3 D0 08

 

BNE

VALID

 

3796

FCD5 BD F1 FA

OPCMP1 LDA

TYPTR2,X

;TEST 2ND PART

3797

FCD8 2D 27 01

 

AND

TMASK2

;INST DOES NOT HAVE SPECIFIED MODE

3798

FCDB F0 E8

 

BEQ

ERRORM

 

3799

FCDD 18

VALID

CLC

 

;FORM FINAL OP CODE

3800

FCDE BD 00 FB

 

LDA

CORR,X

 

3801

FCE1 6D 34 A4

 

ADC

OPCODE

 

3802

FCE4 8D 34 A4

 

STA

OPCODE

 

3803

FCE7

 

 

 

 

3804

FCE7

;PROCESS ADRESSES TO FINAL FORMAT

3805

FCE7 BD 0F FB

 

LDA

SIZEM,X

;OBTAIN ADDRESS FORMAT FROM TABLE

3806

FCEA C9 00

 

CMP

#00

 

3807

FCEC F0 50

 

BEQ

ONEBYT

 

3808

FCEE C9 0F

 

CMP

#$0F

;NEED BRANCH COMPUTATION?

3809

FCF0 F0 1D

 

BEQ

BRNCHC

 

3810

FCF2 8D 33 A4

 

STA

TEMPA

;SAVE START POINT & CHAR COUNT

3811

FCF5 29 0F

 

AND

#$0F

;SEPARATE CHARACTER COUNT

3812

FCF7 A8

 

TAY

 

;LOAD ADDR BYTES INTO Y (0,1,OR 2)

3813

FCF8 8D 2F A4

 

STA

BYTESM

;SAVE IN BYTES

3814

FCFB EE 2F A4

 

INC

BYTESM

;TO INSTR LENGTH (1,2,OR 3 BYTES)

3815

FCFE AD 33 A4

 

LDA

TEMPA

;SEPARATE STARTING POINT

3816

FD01 29 F0

 

AND

#$F0

 

3817

FD03 4A

 

LSR

A

 

3818

FD04 4A

 

LSR

A

 

3819

FD05 4A

 

LSR

A

 

3820

FD06 4A

 

LSR

A

 

3821

FD07 AA

 

TAX

 

;AND PUT IT IN X

3822

FD08 20 12 FD

 

JSR

CONVRT

;CONVERT ASCII ADDRESS TO HEX

3823

FD0B B0 B8

 

BCS

ERRORM

;SKIP OUT IF ERROR IN INPUT

3824

FD0D 90 1D

 

BCC

STASH

 

3825

FD0F 4C 86 FD

BRNCHC JMP

BRCOMP

 

3826

FD12

 

 

 

 

3827

FD12

;############ SUBROUTINE ###############

3828

FD12

;CONVERT FORMATTED ADDRESS INTO PROPER HEX ADDRESS

3829

FD12 BD 33 01

CONVRT LDA

ADFLD,X

;PICK UP 1ST ADDRES CHARACTER

3830

FD15 20 7D EA

 

JSR

HEX

;CONVERT TO MOST SIG HEX

3831

FD18 B0 11

 

BCS

ERRFLG

 

3832

FD1A E8

 

INX

 

;GET NEXT ASCII CHARACTER

3833

FD1B BD 33 01

 

LDA

ADFLD,X

 

3834

FD1E E8

 

INX

 

;POINT TO NEXT CHARACTER, IF ANY

3835

FD1F 20 84 EA

 

JSR

PACK

 

3836

FD22 B0 07

 

BCS

ERRFLG

 

3837

FD24 99 34 A4

 

STA

OPCODE,Y

;SAVE IN MOST SIG. BYTE LOCATION

3838

FD27 88

 

DEY

 

;SET UP FOR NEXT ADDR BYTE, IF ANY

3839

FD28 D0 E8

 

BNE CONVRT

;IF NECESSARY, FORM NEXT ADDR BYTE

3840

FD2A 18

 

CLC

 

 

3841

FD2B 60

ERRFLG RTS

 

;NON HEX CLEARED CARRY

3842

FD2C

;#############

 

3843

FD2C

 

 

 

 

3844

FD2C AC 2F A4

STASH

LDY BYTESM

;SET UP TO STORE COMMAND

3845

FD2F 88

 

DEY

 

 

3846

FD30 B9 34 A4

STSHLP LDA

OPCODE,Y

 

3847

FD33 20 78 EB

 

JSR

SADDR

;STORE ONE BYTE OF COMMAND

3848

FD36 C0 00

 

CPY

#00

 

 

 

 

 

 

 

Page 203
Image 203
Apple II manual OPCMP1 LDA, Brnchc JMP, Convrt LDA

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.