titus-larsen-titus-1981-apple-interfacing

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age caused by careless or incorrect wiring of a test circuit. Once a circuit has been completely tested and debugged, you can probably connect it directly to the data bus of the Apple without any problem. Breadb@aird C@nstrrYdi@rt1 The breadboard circuits may be constructed using wire-wrap techniques, as shown in Fig. 5-9. In this case, the circuits could be expanded and modified through simple wiring changes, but the breadboard itself would be somewhat difficult to use. To aid in interface construction and testing, a printed circuit has been developed in which all of the necessary circuitry has been placed on a single board. The power supply and logic probe circuitry have been incorporated to make the breadboard easy to use. The breadboard is shown in Fig. 5-10, and is available in kit or assembled form from Group Technology, P.O. Box 87B, Check, VA 24072. A large space has been left unused on the breadboard so that a solderless breadboard socket may be mounted directly on the printed-circuit board for easy experimentation. Typical breadboard sockets are the "SK-10" from E & L Instruments, Derby CT 06418 and the "Super Strip" from AP Products, Inc., Mentor, OH 44000. A complete list of parts needed for the breadboard, along with the printed-circuit board artwork is provided in the Appendix. Since the interface breadboard uses a 40-conductor cable to connect to various computers, you will need a means of connecting the
Fig. 5·10. Packaged version of the interface. e to one of the peripheral interface slots in the Apple . We recend the use of a flat cable assembly such as shown in Fig. 5-11. is a printed circuit female edge connector assembly on one end cable, and a 0.1-inch by 0.1-inch female pin grid connector e other. The openings on both connectors must face in the same tion. A ready made cable is available from Group Technology, 00-Cable, which uses a two-foot length of flat cable. actual connections with the Apple bus signals are made with 11 adapter card. This card "twists" and "turns" the various sigo that they are routed from the edge connector to the periphnnector in the Apple. You can easily put together an adapter ng a Vector 4609 prototype card. This card plugs into one of EDGE CONNECTOR TI PIN CONTACTS 0.1" GRID CONNECTOR CABLE-APPROX. 2 FT. Fig. 5·11. Cable for interface. 81
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lJ. 21862 APPLE® INTERFACING JONAT
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APPLE® INTERFACING by Jonathan A.
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Preface The purpose in writing this
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make no attempt to provide much det
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Contents CHAPTER 1 6502 PROCESSOR 9
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CHAPTER 1 6502 Processor The Apple
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Fig. 1- 1. 6502 Microprocessor chip
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locate the memory "cell" that is to
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IR.,view At this point, you should
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Gei'!eral-fi!Jrp@S('; I/ 0 Commaru:
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of an examined memory location. Fro
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will now explore the actions that e
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transfers will require more than ei
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grams are probably easier to write
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·when the Apple computer is progrn
Page 31 and 32: Y@bie ::!1. VNth i
Page 33 and 34: DECODED OUTPUT puter systems, the R
Page 35 and 36: 1 1 1 Using Decoders In many cases,
Page 37 and 38: used in PEEK commands, for example
Page 39 and 40: An alternate approach is to use bot
Page 41 and 42: sections, but the address inputs, A
Page 43 and 44: fUNCTlON TABLES COMPARING CASCADING
Page 45 and 46: flexible decoding scheme, as shown
Page 47 and 48: until the power is turned off. Ther
Page 49 and 50: the logic zero state. In most cases
Page 51 and 52: ue in sequence (in binary), 255, 25
Page 53 and 54: DATA BUS DATA A SN74125 DATA B DATA
Page 55 and 56: R gates that control the enabling o
Page 57 and 58: state of the unused bits cannot be
Page 59 and 60: CHAPTER 4 Flags and Decisions n alm
Page 61 and 62: VALUE 00111010 00011010 11110000 00
Page 63 and 64: •• Addrss Byte Da;a Syie Mexacl
Page 65 and 66: INPUT DEVICE RD 49321 - READY/BUSY
Page 67 and 68: INPUT DEVICE INPUT PORT Dl Dl ' D3
Page 69 and 70: y-language programming will also be
Page 71 and 72: CHAPTER 5 Breadboarding 01 With the
Page 73 and 74: 5 IN4001 (4) 6 ,.___'-'' N:...J LM3
Page 75 and 76: A15 AIO A13 Al2 Al4 All A9 AfJ D .L
Page 77 and 78: In the memory address mode, must pl
Page 79 and 80: PIN CONFIGURATION DJ, LOGIC DIAGRAM
Page 81: The actual ORing of these control s
Page 85 and 86: SIGNAL APPLE PfN INTERFACE PIN +12V
Page 87 and 88: ·.chips have rather slow access ti
Page 89 and 90: are possible, we think that one exp
Page 91 and 92: in most of the experiments unless o
Page 93 and 94: tep 3 You may wish to test other po
Page 95 and 96: ,..,,.,....,"'"' in the block from
Page 97 and 98: None of the outputs should be activ
Page 99 and 100: ---" 2 CLR 20 2 CK Si\17474 The dev
Page 101 and 102: entered and run, It first asks you
Page 103 and 104: +5 Gl\ID LOGIC SWITCHES A B c D 16
Page 105 and 106: PR INT "O"; GOTO 65 If you wish to
Page 107 and 108: am, and the two-byte decimal calcul
Page 109 and 110: for each value that is input to the
Page 111 and 112: of the monitor screen each time the
Page 113 and 114: A = 128 420 B = PEEK(493 l 9) 430 F
Page 115 and 116: il!!lie -2. 0 THEN . . .
Page 117 and 118: program. You may forgotten steps to
Page 119 and 120: The A output, RD 49319, has already
Page 121 and 122: used the following program: FOR A =
Page 123 and 124: · numbers would have to be "split"
Page 125 and 126: tep 1 The input port and output por
Page 127 and 128: 0'"""c"y'·i- the relative values t
Page 129 and 130: and output ports are simply additio
Page 131 and 132: e has been divided into 256 values,
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e converter will not burn out, sinc
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07 DATA BUS DO 3 4 7 a 13 14 17 18
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each decade. The bed code is used i
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LED BIT RED } D3 YELLOW EL M D4 GRE
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: : FOR T = 0 TO 770 NEX T T NEX T
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Thus, by testing the value input fr
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he six LEDs should be removed from
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Yo'1 should be able to develop the
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INPUT "LAST TWO DIGITS ";A$ IF A$ =
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tfhe program first tests the reset
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would you program the computer so t
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Yes. Simply reverse the commands at
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· computer to measure analog volta
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he minimum value should be in the r
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130 Y2 = PEEK(49319)/ 1.594 140 HPL
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You probably will not see much chan
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D7 D6 D5 D4 D3 D2 Dl DO 'b- • "A"
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ll'i!i Name 1 1/0 SELECT 2- 17 A 15
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ADDRESS BUS A7-AO :> MEMORY 256 x 8
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!n!erfac" Slel Addwess lta"%Je 0 C0
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28 INT IN SLOT 6 +5 lK Lr LOCAL INT
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USER 1 This input will allow you to
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puts. You must be careful in your d
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CONTROL/ DATA input at pin 12 ( C/D
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93427 OR EQUIV ROM ADDRESS BUS 1---
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use of red LEDs is recommended, sin
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APPENDIX B Parts Required for the E
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APPENDIX 6502 Microprocessor Techni
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MC§f.500 IE1lriy {D"i) This input
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MCS6500 INSTilUCTION SH-ALPHABETICA
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,, ,, T!M!NG Il-01! READING DI\ TA
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MCS0t-20 PWH¢01 ns PWH¢2 ¢11ou11
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APPENDIX D Apple Interface Breadboa
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APPENDIX E Printed-Circuit Board Ar
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!'i9. E-2. Printecl-
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F t • I +: a... :::> 0 a: (!> 0 (
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Controllers, 14 Converter analog-to
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Pin configuration-cont SN7474, 150
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The Blacksburg Group According to B
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