Norm LDA EXP1 ZERO? | Apple II instruction

F461: 26 F9			ROL	M1
F463: A5 F8		NORM	LDA	X1	EXP1 ZERO?
F465: D0 EE			BNE	NORM1	NO, CONTINUE NORMALIZING.
F467: 60		RTS1	RTS		RETURN.
F468: 20 A4 F4		FSUB	JSR	FCOMPL	CMPL MANT1,CLEARS CARRY UNLESS 0
F46B: 20 7B F4		SWPALGN	JSR	ALGNSWP	RIGHT SHIFT MANT1 OR SWAP WITH
F46E: A5 F4		FADD	LDA	X2
F470: C5 F8			CMP	X1	COMPARE EXP1 WITH EXP2.
F472: D0 F7			BNE	SWPALGN	IF #,SWAP ADDENDS OR ALIGN MANTS.
F474: 20 25 F4			JSR	ADD	ADD ALIGNED MANTISSAS.
F477: 50	EA	ADDEND	BVC	NORM	NO OVERFLOW, NORMALIZE RESULT.
F479: 70	05		BVS	RTLOG	OV: SHIFT M1 RIGHT, CARRY INTO SIGN
F47B: 90	C4	ALGNSWP	BCC	SWAP	SWAP IF CARRY CLEAR,

*ELSE SHIFT RIGHT ARITH.

F47D: A5 F9	RTAR	LDA	M1	SIGN OF MANT1 INTO CARRY FOR
F47F: 0A		ASL		RIGHT ARITH SHIFT.
F480: E6 F8	RTLOG	INC	X1	INCR X1 TO ADJUST FOR RIGHT SHIFT
F482: F0 75		BEQ	OVFL	EXP1 OUT OF RANGE.
F484: A2 FA	RTLOG1	LDX	#$FA	INDEX FOR 6:BYTE RIGHT SHIFT.
F486: 76 FF	ROR1	ROR	E+3,X
F488: E8		INX		NEXT BYTE OF SHIFT.
F489: D0 FB		BNE	ROR1	LOOP UNTIL DONE.
F48B: 60		RTS		RETURN.
F48C: 20 32 F4	FMUL	JSR	MD1	ABS VAL OF MANT1, MANT2
F48F: 65 F8		ADC	X1	ADD EXP1 TO EXP2 FOR PRODUCT EXP
F491: 20 E2 F4		JSR	MD2	CHECK PROD. EXP AND PREP. FOR MUL
F494: 18		CLC		CLEAR CARRY FOR FIRST BIT.
F495: 20 84 F4	MUL1	JSR	RTLOG1	M1 AND E RIGHT (PROD AND MPLIER)
F498: 90 03		BCC	MUL2	IF CARRY CLEAR, SKIP PARTIAL PROD
F49A: 20 25 F4		JSR	ADD	ADD MULTIPLICAND TO PRODUCT.
F49D: 88	MUL2	DEY		NEXT MUL ITERATION.
F49E: 10 F5		BPL	MUL1	LOOP UNTIL DONE.
F4A0: 46 F3	MDEND	LSR	SIGN	TEST SIGN LSB.
F4A2: 90 BF	NORMX	BCC	NORM	IF EVEN,NORMALIZE PROD,ELSE COMP
F4A4: 38	FCOMPL	SEC		SET CARRY FOR SUBTRACT.
F4A5: A2 03		LDX	#$3	INDEX FOR 3 BYTE SUBTRACT.
F4A7: A9 00	COMPL1	LDA	#$0	CLEAR A.
F4A9: F5 F8		SBC	X1,X	SUBTRACT BYTE OF EXP1.
F4AB: 95 F8		STA	X1,X	RESTORE IT.
F4AD: CA		DEX		NEXT MORE SIGNIFICANT BYTE.
F4AE: D0 F7		BNE	COMPL1	LOOP UNTIL DONE.
F4B0: F0 C5		BEQ	ADDEND	NORMALIZE (OR SHIFT RT IF OVFL).
F4B2: 20 32 F4	FDIV	JSR	MD1	TAKE ABS VAL OF MANT1, MANT2.
F4B5: E5 F8		SBC	X1	SUBTRACT EXP1 FROM EXP2.
F4B7: 20 E2 F4		JSR	MD2	SAVE AS QUOTIENT EXP.
F4BA: 38	DIV1	SEC		SET CARRY FOR SUBTRACT.
F4BB: A2 02		LDX	#$2	INDEX FOR 3-BYTE SUBTRACTION.
F4BD: B5 F5	DIV2	LDA	M2,X
F4BF: F5 FC		SBC	E,X	SUBTRACT A BYTE OF E FROM MANT2.
F4C1: 48		PHA		SAVE ON STACK.
F4C2: CA		DEX		NEXT MORE SIGNIFICANT BYTE.
F4C3: 10 F8		BPL	DIV2	LOOP UNTIL DONE.
F4C5: A2 FD		LDX	#$FD	INDEX FOR 3-BYTE CONDITIONAL MOVE
F4C7: 68	DIV3	PLA		PULL BYTE OF DIFFERENCE OFF STACK
F4C8: 90 02		BCC	DIV4	IF M2<E THEN DON'T RESTORE M2.
F4CA: 95 F8		STA	M2+3,X
F4CC: E8	DIV4	INX		NEXT LESS SIGNIFICANT BYTE.
F4CD: D0 F8		BNE	DIV3	LOOP UNTIL DONE.
F4CF: 26 FB		ROL	M1+2
F4D1: 26 FA		ROL	M1+1	ROLL QUOTIENT LEFT, CARRY INTO LSB
F4D3: 26 F9		ROL	M1
F4D5: 06 F7		ASL	M2+2

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.

NORM

LDA

EXP1 ZERO?

II specifications