F884: A4 3B

181

 

LDY

PCH

 

F886: 20 96 FD

182

 

JSR

PRYX2

 

F889: 20 48 F9

183

 

JSR

PRBLNK

;FOLLOWED BY A BLANK

F88C: A1 3A

184

 

LDA

(PCL,X)

;GET OP CODE

F88E: A8

185

INSDS2

TAY

 

 

F88F: 4A

186

 

LSR

 

;EVEN/ODD TEST

F890: 90 09

187

 

BCC

IEVEN

 

F892: 6A

188

 

ROR

 

;BIT 1 TEST

F893: B0 10

189

 

BCS

ERR

;XXXXXX11 INVALID OP

F895: C9 A2

190

 

CMP

#$A2

 

F897: F0 0C

191

 

BEQ

ERR

;OPCODE $89 INVALID

F899: 29 87

192

 

AND

#$87

;MASK BITS

F89B: 4A

193

IEVEN

LSR

 

;LSB INTO CARRY FOR L/R TEST

F89C: AA

194

 

TAX

 

 

F89D: BD 62 F9

195

 

LDA

FMT1,X

;GET FORMAT INDEX BYTE

F8A0: 20 79 F8

196

 

JSR

SCRN2

;R/L H-BYTE ON CARRY

F8A3: D0 04

197

 

BNE

GETFMT

 

F8A5: A0 80

198

ERR

LDY

#$80

;SUBSTITUTE $80 FOR INVALID OPS

F8A7: A9 00

199

 

LDA

#$00

;SET PRINT FORMAT INDEX TO 0

F8A9: AA

200

GETFMT

TAX

 

 

F8AA: BD A6 F9

201

 

LDA

FMT2,X

;INDEX INTO PRINT FORMAT TABLE

F8AD: 85 2E

202

 

STA

FORMAT

;SAVE FOR ADR FIELD FORMATTING

F8AF: 29 03

203

 

AND

#$03

;MASK FOR 2-BIT LENGTH

 

204

 

 

 

; (P=1 BYTE, 1=2 BYTE, 2=3 BYTE)

F8B1: 85 2F

205

 

STA

LENGTH

 

F8B3: 98

206

 

TYA

 

;OPCODE

F8B4: 29 8F

207

 

AND

#$8F

;MASK FOR 1XXX1010 TEST

F8B6: AA

208

 

TAX

 

; SAVE IT

F8B7: 98

209

 

TYA

 

;OPCODE TO A AGAIN

F8B8: A0 03

210

 

LDY

#$03

 

F8BA: E0 8A

211

 

CPX

#$8A

 

F8BC: F0 0B

212

 

BEQ

MNNDX3

 

F8BE: 4A

213

MNNDX1

LSR

 

 

F8BF: 90 08

214

 

BCC

MNNDX3

;FORM INDEX INTO MNEMONIC TABLE

F8C1: 4A

215

 

LSR

 

 

F8C2: 4A

216

MNNDX2

LSR

 

;1) 1XXX1010->00101XXX

F8C3: 09 20

217

 

ORA

#$20

;2) XXXYYY01->00111XXX

F8C5: 88

218

 

DEY

 

;3) XXXYYY10->00110XXX

F8C6: D0 FA

219

 

BNE

MNNDX2

;4) XXXYY100->00100XXX

F8C8: C8

220

 

INY

 

;5) XXXXX000->000XXXXX

F8C9: 88

221

MNNDX3

DEY

 

 

F8CA: D0 F2

222

 

BNE

MNNDX1

 

F8CC: 60

223

 

RTS

 

 

F8CD: FF FF FF

224

 

DFB $FF,$FF,$FF

 

F8D0: 20 82 F8

225

INSTDSP

JSR

INSDS1

;GEN FMT, LEN BYTES

F8D3: 48

226

 

PHA

 

;SAVE MNEMONIC TABLE INDEX

F8D4: B1 3A

227

PRNTOP

LDA

(PCL),Y

 

F8D6: 20 DA FD

228

 

JSR

PRBYTE

 

F8D9: A2 01

229

 

LDX

#$01

;PRINT 2 BLANKS

F8DB: 20 4A F9

230

PRNTBL

JSR

PRBL2

 

F8DE: C4 2F

231

 

CPY

LENGTH

;PRINT INST (1-3 BYTES)

F8E0: C8

232

 

INY

 

;IN A 12 CHR FIELD

F8E1: 90 F1

233

 

BCC

PRNTOP

 

F8E3: A2 03

234

 

LDX

#$03

;CHAR COUNT FOR MNEMONIC PRINT

F8E5: C0 04

235

 

CPY

#$04

 

F8E7: 90 F2

236

 

BCC

PRNTBL

 

F8E9: 68

237

 

PLA

 

;RECOVER MNEMONIC INDEX

F8EA: A8

238

 

TAY

 

 

F8EB: B9 C0 F9

239

 

LDA

MNEML,Y

 

F8EE: 85 2C

240

 

STA

LMNEM

;FETCH 3-CHAR MNEMONIC

F8F0: B9 00 FA

241

 

LDA

MNEMR,Y

; (PACKED IN 2-BYTES)

F8F3: 85 2D

242

 

STA

RMNEM

 

 

 

 

 

 

 

Page 22
Image 22
Apple II manual Ldy Pch

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.