CBP Comp 1017 Digital Technologies1

CBP Comp 1017 Digital Technologies2

CBP Comp 1017 Digital Technologies3 Patron Saint of England, Moscow, Boy Scouts, the Italian calvary, chivalry, Istanbul, Aragon, Beirut, Portugal, Germany, Genoa, and Venice. In the East, he is the patron of soldiers, and also of husbandmen … Representation Dr.C Comp 1017

CBP Comp 1017 Digital Technologies4 … Representations Images Characters Numbers Music electronics

CBP Comp 1017 Digital Technologies5 Bits and Electronics s 4s 2s 1s = 9 Example Electronics … a wire can be on (“1”) or off (“0”) Electric signals The Magic … numbers are bits are electric signals

CBP Comp 1017 Digital Technologies6 Numbers are Bits x x x x x ? x 16 + ? x 8 + ? x 4 + ? x 2 + ? x 1 example question

CBP Comp 1017 Digital Technologies7 Counting in Binary 1s2s s

CBP Comp 1017 Digital Technologies8 CPU MemI/O Application Functional Blocks Transistors

CBP Comp 1017 Digital Technologies9 N-MOS in P-MOS in CMOS : Complementary Transistors

CBP Comp 1017 Digital Technologies10 N-MOS In = 0 In = 1 P-MOS In = 1 In = 0 Transistors are Switches

CBP Comp 1017 Digital Technologies in out Transistor Symbols Logic Gate Symbol Representing Electronics

CBP Comp 1017 Digital Technologies on offon off

CBP Comp 1017 Digital Technologies B AB A out 1 0 ABO AND gate A B O/P X

CBP Comp 1017 Digital Technologies14 Digital Logic Gates. AND gate A B O/P ABO LOGIC SYMBOL TRUTH TABLE

CBP Comp 1017 Digital Technologies15 Digital Logic Lab ABO input switches A B O OR gate NOT gate NOR gate NAND gate

CBP Comp 1017 Digital Technologies16 Combinations of Gates 34 bU1 Inverter 34 bU1 Inverter Sum is greater than the parts

CBP Comp 1017 Digital Technologies17 Exercise - Find the Truth Table A B C ABCO P P O AND gate

CBP Comp 1017 Digital Technologies18 Investigation of Single Neurons Microelectrode recording of Biological Neuron activation using tungsten electrode Hubel and Weisel. Nobel Prize 1958 Photomicrograph: Height = 1mm.

CBP Comp 1017 Digital Technologies19 Biological AND and NOT Neuron output fires only if both inputs are 1 INHIBITORY synapse : Input high 1 prevents neuron firing Inhibitory synapse

CBP Comp 1017 Digital Technologies20 Two Gate Memory Cell 12 aU1 34 b 34 b Electronic Inverter Two inverters + feedback 12 aU1 34 b Choose input 0 or 1. Follow it through two invertors with feedback. States are consistent. Two possible solutions. These are two memory states.

CBP Comp 1017 Digital Technologies21 SRAM Memory Cell 12 aU1 34 b 12 a 34 b select In/out bit 12 aU1 34 b Two inverters + feedback Neural Circuits SRAM Memory 0 1

CBP Comp 1017 Digital Technologies22 STM and LTM Before Learning After Learning A A B B Short Term Memory : Cycling data between groups of neurons 0 1 Long Term Memory : Change in strength of synapse connexion Random Access Memory (RAM) Hard Disk Drive

CBP Comp 1017 Digital Technologies23 How Many Numbers with N-bits ? from 0 to 3 are 4 numbers What are they ? from 0 to 7 are 8 numbers

CBP Comp 1017 Digital Technologies24 Biggest Number Represented ? = 15 (dec) One less = ? (dec) One less With 4 bits ? With 8 bits ?

CBP Comp 1017 Digital Technologies25 Memory Addressing CPU 2-bit address = 4 memory cells 3-bit address = 8 memory cells

CBP Comp 1017 Digital Technologies26 Questions So what size memory with 8 bits of address ? So what size memory with 16 bits of address ? …

CBP Comp 1017 Digital Technologies27 Data and Address Buses address bus 16 bits ? Max number of memory cells ? Memory 16 bits CPU 8 bits A A D Data bus 8 bits ? Max number which can be stored in each cell ? D

CBP Comp 1017 Digital Technologies28 Representing Characters - ASCII ASCII 8bits 256 characters Unicode 16bits ISO 36bits 17 million ASCII (American National Standards Institute ANSI) American Standard Code for Information Interchange The code for H is , for e is So the message “Hello.” can be coded as

CBP Comp 1017 Digital Technologies29 Unicode HEXAscii A 61a 6Dm 0DCR ASCII UNICODE Babelmap

CBP Comp 1017 Digital Technologies30 Adding Colored Light All colors of light can be made from the addition of RED + GREEN + BLUE e.g. RED + GREEN = YELLOW

CBP Comp 1017 Digital Technologies31 Three Images Make One RGB (Red Green Blue) Red + Green + Blue=

CBP Comp 1017 Digital Technologies32 Images “IView” Applet Zoomed area Zoom here + + = Red, green and Blue PIXELS

CBP Comp 1017 Digital Technologies Video memory “planes” Each PIXEL has 3 SAMPLES R G B + + = = PIXELSAMPLES Cathode Ray Tube (CRT) screen

CBP Comp 1017 Digital Technologies bits per pixel BIU Graphics Processor DAC’s CRT memory planes

CBP Comp 1017 Digital Technologies35 You recognize this guy. But SQUINT while looking. The image appears very much clearer. Yes! Defocussing the image gets more information to your brain. How? By removing distracting info pro- duced by the sharp pixel edges

CBP Comp 1017 Digital Technologies36 Image Processing Applet ImagePixelsConvolution KERNEL

CBP Comp 1017 Digital Technologies37 How convolution works Scan KERNEL OVER whole image, pixel by pixel and at each point do this, e.g, (1 x 4) + (2 x 8) + (1 x 4) = 24, divide by 4 = 6 Divide = 4 input image output image

CBP Comp 1017 Digital Technologies38 Hexadecimal Representation We need a shorthand for representing binary numbers. Divide a byte (8 bits) into two 4-bit nibbles Each nibble can be ABCDEF89ABCDEF … so we have E6 E6

CBP Comp 1017 Digital Technologies39 Use of Hexadecimals 2. Assembler Programming addressesAssembler code Yellow is FFFF00 This means FF 255 FF RGBRGB 1. Web colours in HTML

CBP Comp 1017 Digital Technologies40 Steganography

CBP Comp 1017 Digital Technologies41 Sound Representation - Demo Microcontrollerloudspeaker

CBP Comp 1017 Digital Technologies42 Digital and Analogue Data Digital Loaf of Bread Notes of flute Light On or Off Binary 0 or 1 Analogue Glass of Water Notes of cello Light Dimmer Number

CBP Comp 1017 Digital Technologies43 Sound Representation recording Analogue from instrument Digital Representation Sampled signal playback

CBP Comp 1017 Digital Technologies44 Page 461 MIDI Representation Each track stored as sequence List of instructions to instrument how to play music. Does not contain sounds but instructions how to make them Midi instruments read these instructions and make the sounds represented by the instructions

CBP Comp 1017 Digital Technologies45 The Abundance of Logic Digital logic AND AND in neurons AND in programming if (x == 2 ) && (y == 3 )) gohome AND in language (Holmes was a detective) AND (Holmes was on the case)

CBP Comp 1017 Digital Technologies46 Why have we done all this ? Leibnitz (17 th C) saw the need to make a machine to prove mathematical and logical theorems – that means could “reason” about a problem George Boole (19 th C) produced symbolic logic (AND, NOT, NOR) which could simplify this process and capture most of “everyday reasoning” using only two states 0 and 1. Claude Shannon (20 th C) showed how Boole’s logic could be implemented by electronic Logic GATES which were digital using only 0 or 1 Alan Turing (20 th C) showed how these problems could be solved by a simple “central processor” and a “storage tape”. This is our Computer! Bohme and Jacopini showed that any complex set of instructions to solve these problems could be broken down into simple programming constructs, e.g. “ if (this) then do that”