LSR Cpiy Make Room for MSB | Apple II manual

2151	EE2E 4E 2A A4		LSR	CPIY	;MAKE ROOM FOR MSB
2152	EE31 0D 2A A4		ORA	CPIY	;OR IN SIGN BIT
2153	EE34 8D 2A A4		STA CPIY		;REPLACE CHAR
2154	EE37 88		DEY
2155	EE38 D0 F1		BNE	GETA1
2156	EE3A 60		RTS
2157	EE3B	;GET ONE BIT FROM TAPE AND
2158	EE3B	;RETURN IT		IN SIGN OF A (MSB)
2159	EE3B AD 08 A4	RDBIT	LDA	TSPEED	;ARE WE IN C7 OR 5B,5A FREQUENC`
2160	EE3E 30 27		BMI	RDBIT4	;JUMP TO C7 FREQ FORMAT
2161	EE40 20 75 EE		JSR	CKFREQ	;START BIT IN HIGH FREQ
2162	EE43 20 75 EE	RDBIT1 JSR		CKFREQ	;HIGH TO LOW FREQ TRANS
2163	EE46 B0 FB		BCS	RDBIT1
2164	EE48 AD 96 A4		LDA DIV64		;GET HIGH FREQ TIMING
2165	EE4B 48		PHA
2166	EE4C A9 FF		LDA #$FF		;SET UP TIMER
2167	EE4E 8D 96 A4		STA	DIV64
2168	EE51 20 75 EE	RDBIT2 JSR		CKFREQ	;LOW TO HIGH FREQ TRANS
2169	EE54 90 FB		BCC RDBIT2		;WAIT TILL FREQ IS HIGH
2170	EE56 68		PLA
2171	EE57 38		SEC
2172	EE58 ED 96 A4		SBC DIV64		;(256-T1) - (256-T2) =T2-T1
2173	EE5B 48		PHA		;LOW FREQ TIME-HIGH FREQ TIME
2174	EE5C A9 FF		LDA	#$FF
2175	EE5E 8D 96 A4		STA DIV64		;SET UP TIMER
2176	EE61 68		PLA
2177	EE62 49 FF		EOR	#$FF
2178	EE64 29 80		AND	#$80
2179	EE66 60		RTS
2180	EE67	;EACH BIT STARTS WITH HALF PULSE OF 2400 & THEN
2181	EE67	;3 HALF PULSES OF 1200 HZ FOR 0 ,3 PUSLES OF 2400 FOR 1
2182	EE67	;THE READING IS MADE ON THE FOURTH 1/2 PULSE ,WHERE
2183	EE67	;THE SIGNAL HAS STABILIZED
2184	EE67 20 75 EE	RDBIT4 JSR CKFREQ			;SEE WHICH FREQ
2185	EE6A 90 FB		BCC	RDBIT4
2186	EE6C 20 75 EE		JSR	CKFREQ
2187	EE6F 20 75 EE		JSR	CKFREQ
2188	EE72 4C B5 FF		JMP PATC24		;NOW READ THE BIT
2189	EE75
2190	EE75 2C 00 A8	CKFREQ BIT DRB			;ARE WE HIGH OR LOW ?
2191	EE78 30 27		BMI	CKF4
2192	EE7A 2C 00 A8	CKF1	BIT	DRB	;WAIT TILL HIGH
2193	EE7D 10 FB		BPL	CKF1
2194	EE7F 65 00		ADC	$00	;EQUALIZER
2195	EE81 AD 09 A8	CKF2	LDA T2H		;SAVE CNTR
2196	EE84 48		PHA
2197	EE85 AD 08 A8		LDA	T2L
2198	EE88 48		PHA
2199	EE89 A9 FF		LDA	#$FF
2200	EE8B 8D 09 A8		STA	T2H	;START CNTR
2201	EE8E AD 08 A4		LDA	TSPEED
2202	EE91 30 06		BMI CKF3		;SUPER SPEED ?
2203	EE93 68		PLA
2204	EE94 CD 08 A4		CMP TSPEED		;HIGH OR LOW FREC
2205	EE97 68		PLA		;C=1 IF HIGH ,C=0 IF LOW
2206	EE98 60		RTS
2207	EE99 68	CKF3	PLA
2208	EE9A CD 08 A4		CMP TSPEED		;CENTER FREQ
2209	EE9D 68	CKF3A	PLA
2210	EE9E E9 FE		SBC	#$FE
2211	EEA0 60		RTS
2212	EEA1 2C 00 A8	CKF4	BIT DRB		;WAIT TILL LOW

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 LSR Cpiy Make Room for MSB

Models: II

LSR

CPIY

;MAKE ROOM FOR MSB

ORA

EOR

ADC

II specifications