NXTA4 INC A4L Incr 2-BYTE A4 | Apple II instruction

FCB3: 60	705		RTS
FCB4: E6 42	706	NXTA4	INC	A4L	;INCR 2-BYTE A4
FCB6: D0 02	707		BNE	NXTA1	;	AND A1
FCB8: E6 43	708		INC	A4H
FCBA: A5 3C	709	NXTA1	LDA	A1L	;INCR 2-BYTE A1.
FCBC: C5 3E	710		CMP	A2L
FCBE: A5 3D	711		LDA	A1H	;	AND COMPARE TO A2
FCC0: E5 3F	712		SBC	A2H
FCC2: E6 3C	713		INC	A1L	;	(CARRY SET IF >=)
FCC4: D0 02	714		BNE	RTS4B
FCC6: E6 3D	715		INC	A1H
FCC8: 60	716	RTS4B	RTS
FCC9: A0 4B	717	HEADR	LDY	#$4B	;WRITE A*256 'LONG 1'
FCCB: 20 DB FC	718		JSR	ZERDLY	;	HALF CYCLES
FCCE: D0 F9	719		BNE	HEADR	;	(650 USEC EACH)
FCD0: 69 FE	720		ADC	#$FE
FCD2: B0 F5	721		BCS	HEADR	;THEN A 'SHORT 0'
FCD4: A0 21	722		LDY	#$21	;	(400 USEC)
FCD6: 20 DB FC	723	WRBIT	JSR	ZERDLY	;WRITE TWO HALF CYCLES
FCD9: C8	724		INY		;	OF 250 USEC ('0')
FCDA: C8	725		INY		;	OR 500 USEC ('0')
FCDB: 88	726	ZERDLY	DEY
FCDC: D0 FD	727		BNE	ZERDLY
FCDE: 90 05	728		BCC	WRTAPE	;Y IS COUNT FOR
FCE0: A0 32	729		LDY	#$32	;	TIMING LOOP
FCE2: 88	730	ONEDLY	DEY
FCE3: D0 FD	731		BNE	ONEDLY
FCE5: AC 20 C0	732	WRTAPE	LDY	TAPEOUT
FCE8: A0 2C	733		LDY	#$2C
FCEA: CA	734		DEX
FCEB: 60	735		RTS
FCEC: A2 08	736	RDBYTE	LDX	#$08	;8 BITS TO READ
FCEE: 48	737	RDBYT2	PHA		;READ TWO TRANSITIONS
FCEF: 20 FA FC	738		JSR	RD2BIT	;	(FIND EDGE)
FCF2: 68	739		PLA
FCF3: 2A	740		ROL		;NEXT BIT
FCF4: A0 3A	741		LDY	#$3A	;COUNT FOR SAMPLES
FCF6: CA	742		DEX
FCF7: D0 F5	743		BNE	RDBYT2
FCF9: 60	744		RTS
FCFA: 20 FD FC	745	RD2BIT	JSR	RDBIT
FCFD: 88	746	RDBIT	DEY		;DECR Y UNTIL
FCFE: AD 60 C0	747		LDA	TAPEIN	; TAPE TRANSITION
FD01: 45 2F	748		EOR	LASTIN
FD03: 10 F8	749		BPL	RDBIT
FD05: 45 2F	750		EOR	LASTIN
FD07: 85 2F	751		STA	LASTIN
FD09: C0 80	752		CPY	#$80	;SET CARRY ON Y
FD0B: 60	753		RTS
FD0C: A4 24	754	RDKEY	LDY	CH
FD0E: B1 28	755		LDA	(BASL),Y	;SET SCREEN TO FLASH
FD10: 48	756		PHA
FD11: 29 3F	757		AND	#$3F
FD13: 09 40	758		ORA	#$40
FD15: 91 28	759		STA	(BASL),Y
FD17: 68	760		PLA
FD18: 6C 38 00	761		JMP	(KSWL)	;GO TO USER KEY-IN
FD1B: E6 4E	762	KEYIN	INC	RNDL
FD1D: D0 02	763		BNE	KEYIN2	;INCR RND NUMBER
FD1F: E6 4F	764		INC	RNDH
FD21: 2C 00 C0	765	KEYIN2	BIT	KBD	;KEY DOWN?
FD24: 10 F5	766		BPL	KEYIN	;	LOOP

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 NXTA4 INC A4L Incr 2-BYTE A4

Models: II

NXTA4

INC

A4L

;INCR 2-BYTE A4

II specifications