1841

EBEA 20 23 EC

 

JSR

DEHALF

;DELAY 1/2 BIT TIME

1842

EBED AD 00 A8

GET3

LDA

DRB

;GET 8 BITS

1843

EBF0 29 40

 

AND

#$40

;MASK OFF OTHER BITS,ONLY PB6

1844

EBF2 4E 2A A4

 

LSR

CPIY

;SHIFT RIGHT CHARACTER

1845

EBF5 0D 2A A4

 

ORA

CPIY

 

1846

EBF8 8D 2A A4

 

STA

CPIY

 

1847

EBFB 20 0F EC

 

JSR DELAY

;DELAY 1 BIT TIME

1848

EBFE CA

 

DEX

 

 

1849

EBFF D0 EC

 

BNE GET3

;GET NEXT BIT

1850

EC01 20 0F EC

 

JSR DELAY

;DO NOT CARE FOR PARITY BIT

1851

EC04 20 23 EC

 

JSR DEHALF

;UNTIL WE GET BACK TO ONE AGAIN

1852

EC07 68

 

PLA

 

;RESTORE X

1853

EC08 AA

 

TAX

 

 

1854

EC09 AD 2A A4

 

LDA

CPIY

 

1855

EC0C 29 7F

 

AND #$7F

;CLEAR PARITY BIT

1856

EC0E 60

 

RTS

 

 

1857

EC0F

 

 

 

 

1858

EC0F

;DELAY

1 BIT TIME AS GIVEN BY BAUD RATE

1859

EC0F AD 18 A4

DELAY

LDA CNTL30

;START TIMER T2

1860

EC12 8D 08 A8

 

STA

T2L

 

1861

EC15 AD 17 A4

 

LDA

CNTH30

 

1862

EC18 8D 09 A8

DE1

STA

T2H

 

1863

EC1B AD 0D A8

DE2

LDA

IFR

;GET INT FLG FOR T2

1864

EC1E 29 20

 

AND

#MT2

 

1865

EC20 F0 F9

 

BEQ DE2

;TIME OUT ?

1866

EC22 60

 

RTS

 

 

1867

EC23

 

 

 

 

1868

EC23

;DELAY HALF BIT TIME

 

1869

EC23

;TOTAL TIME DIVIDED BY 2

1870

EC23 AD 17 A4

DEHALF LDA

CNTH30

 

1871

EC26 4A

 

LSR

A

;LSB TO CARRY

1872

EC27 AD 18 A4

 

LDA

CNTL30

 

1873

EC2A 6A

 

ROR

A

;SHIFT WITH CARRY

1874

EC2B 8D 08 A8

 

STA

T2L

 

1875

EC2E AD 17 A4

 

LDA

CNTH30

 

1876

EC31 4A

 

LSR

A

 

1877

EC32 8D 09 A8

 

STA

T2H

 

1878

EC35 4C 1B EC

 

JMP

DE2

 

1879

EC38

 

 

 

 

1880

EC38

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

1881

EC38 A9 00

GETKD0

LDA

#0

 

1882

EC3A 8D 77 A4

 

STA

IDOT

;GO ANOTHER 90 DOTS

1883

EC3D 20 50 F0

 

JSR IPO0

;OUTPUT 90 DOTS TO PRI (ZEROS)

1884

EC40

 

 

 

 

1885

EC40

;GET A CHAR FROM KB SUBROUTINE

1886

EC40

;FROM KB Y=ROW ,STBKEY=COLUMNS (STROBE)

1887

EC40

;X=CTRL OR

SHIFT ,OTHERWISE X=0

1888

EC40 20 EF EC

GETKEY JSR

ROONEK

;WAIT IF LAST KEY STILL DOWN

1889

EC43 20 2A ED

GETKY

JSR DEBKEY

;DEBOUNCE KEY (5 MSEC)

1890

EC46

;CTRL OR SHIFT ?

 

1891

EC46 A9 8F

 

LDA #$8F

;CHCK CLMN 5,6,7

1892

EC48 8D 80 A4

 

STA

DRA2

 

1893

EC4B AD 82 A4

 

LDA

DRB2

;CHCK ROW 1

1894

EC4E 4A

 

LSR

A

 

1895

EC4F B0 20

 

BCS

GETK1

;IF=1 ,NO CTRL OR SHIFT

1896

EC51 A2 03

 

LDX

#3

;CLMN 5,6,7 (CNTRL,SHIFTL,SHIFTR)

1897

EC53 A9 7F

 

LDA #$7F

;CTRL OR SHIFT ,SO WHICH ONE?

1898

EC55 38

GETK0

SEC

 

 

1899

EC56 6A

 

ROR

A

 

1900

EC57 48

 

PHA

 

 

1901

EC58 20 0B ED

 

JSR ONEK2

;LETS GET CTRL OR SHIFT INTO X

1902

EC5B AD 82 A4

 

LDA

DRB2

 

 

 

 

 

 

 

Page 170
Image 170
Apple II manual Ora, Dehalf 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.