SEI Disable Interrupt | Apple II instruction

0363	E0C0 78					SEI		;DISABLE INTERRUPT
0364	E0C1 A2		FF			LDX #$FF		;INIT STACK PTR
0365	E0C3 9A					TXS
0366	E0C4 8E		24	A4		STX SAVS		;ALSO INIT SAVED STACK PTR
0367	E0C7				;INITIALIZE 6522
0368	E0C7 A2		0E			LDX	#14
0369	E0C9 BD		43	E7	RS1	LDA	INTAB1,X	;PB1-PB0,PA7-PA0 FOR PRNTR
0370	E0CC 9D		00	A8		STA	DRB,X	;PB2=TTO,PB6=TTI
0371	E0CF CA					DEX		;PB4-PB5=TAPE CONTROL,PB7=DATA
0372	E0D0 10		F7			BPL	RS1	;PB3 =SWITCH KB/TTY
0373	E0D2				;INITIALIZE 6532
0374	E0D2 A2		03			LDX	#3	;PORTS USED FOR KB
0375	E0D4 BD		52	E7	RS2	LDA	INTAB2,X	;PA0-PA7 AS OUTPUT
0376	E0D7 9D		80	A4		STA DRA2,X		;PB0-PB7 AS INPUT
0377	E0DA CA					DEX
0378	E0DB 10		F7			BPL	RS2
0379	E0DD				;INITIALIZE MONITOR RAM (6532)
0380	E0DD AD		56	E7		LDA INTAB3		;CHECK IF NMIV2 HAS BEEN CHANGED
0381	E0E0 CD		02	A4		CMP NMIV2		;IF IT HAS THEN ASSUME A COLD
0382	E0E3 D0		0C			BNE RS3A		;START AND INITIALIZE EVERYTHING
0383	E0E5 AD		57	E7		LDA	INTAB3+1
0384	E0E8 CD		03	A4		CMP	NMIV2+1
0385	E0EB D0		04			BNE	RS3A
0386	E0ED A2		10			LDX	#16	;THEY ARE EQUAL ,IT'S A WARM RESET
0387	E0EF D0		02			BNE	RS3
0388	E0F1 A2		00		RS3A	LDX	#0	;INIT EVERYTHING (POWER UP)
0389	E0F3 BD		56	E7	RS3	LDA	INTAB3,X
0390	E0F6 9D		02	A4		STA	NMIV2,X
0391	E0F9 E8					INX
0392	E0FA E0		15			CPX	#21
0393	E0FC 90		F5			BCC	RS3
0394	E0FE				;INITIALIZE DISPLAY (6520)
0395	E0FE A9		00			LDA	#0	;SET CONTR REG FOR DATA DIR REG
0396	E100	A2	01			LDX	#1
0397	E102	20	13	E1		JSR	SETREG
0398	E105	A9	FF			LDA #$FF		;SET DATA DIR REG FOR OUTPUT
0399	E107	CA				DEX
0400	E108	20	13	E1		JSR	SETREG
0401	E10B A9		04			LDA #$04		;SET CONTR REG FOR PORTS
0402	E10D E8					INX
0403	E10E 20		13	E1		JSR	SETREG
0404	E111	D0	07			BNE	RS3B
0405	E113	9D	00	AC	SETREG STA		RA,X
0406	E116	9D	02	AC		STA	RB,X
0407	E119	60				RTS
0408	E11A 58				RS3B	CLI		;CLEAR INTERRUPT
0409	E11B
0410	E11B				;KB/TTY SWITCH TEST AND BIT RATE MEASUREMENT
0411	E11B A9		08			LDA #$08		;PB3=SWITCH KB/TTY
0412	E11D 2C		00	A8	RS4	BIT DRB		;A^M ,PB6-> V (OVERFLOW FLG)
0413	E120	D0	22			BNE RS7		;BRANCH ON KB
0414	E122	70	F9			BVS RS4		;START BIT=PB6=0?
0415	E124	A9	FF			LDA #$FF		;YES ,INITIALIZE TIMER T2
0416	E126	8D	09	A8		STA	T2H
0417	E129	2C	00	A8	RS5	BIT	DRB	;END OF START BIT ?
0418	E12C 50		FB			BVC	RS5	;NO ,WAIT UNTIL PB6 BACK TO 1
0419	E12E AD		09	A8		LDA	T2H	;STORE TIMING
0420	E131	49	FF			EOR	#$FF	;COMPLEMENT
0421	E133	8D	17	A4		STA	CNTH30
0422	E136	AD	08	A8		LDA	T2L
0423	E139	49	FF			EOR	#$FF
0424	E13B 20		7C	FE		JSR	PATCH1	;ADJUST IT

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.

SEI

;DISABLE INTERRUPT

CMP

EOR

EOR

II specifications