Ora, Dehalf LDA | Apple II manual

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

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.

Apple II manual Ora, Dehalf LDA

Models: II

ORA

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DEHALF LDA

II specifications