PMC Exhibit 2068
`PMC Exhibit 2068
`Apple v. PMC
`Apple v. PMC
`|PR2016—OO753
`IPR2016-00753
`Page 1
`Page 1
`
`

`
`wireless
`world _
`
`V0183’
`
`. No 1496
`
`Contents
`
`35 Time, gentlemen, please
`36 NRDC surround-sound system by M. A. Gerzon
`39 News
`.
`
`40 Characteristics and load lines — 5 by S. W. Amos
`44 Wireless World amateur radio station
`
`i
`
`45 Sensitive metal detector by D. E. O'N. Waddirzgton
`48 H.F. predictions‘
`‘
`53 New of themonth
`Bullock’s boardroom and the engineer
`Britain pioneered the integrated circuit"
`Vmos devices “middle of this year”
`Education by radio in Honduras by M. K. Bates
`Literature received. 100 years ago
`Circuit ideas
`'
`1
`Simple noise generator
`Variable band-pass filter
`Ripple eliminator
`Viewdata — 3 by S. Fedida
`V
`World of amateur radio
`Electronic rhythm unit —- 2 by A. Battaiotto and G. Ronzi
`Letters to the editor
`I
`The Warden Report
`Current dumping amplifier
`. Advanced pre-amplifier design
`Broadcast stereo coder by T. Brook
`Power semiconductors by M. R. Sagin
`New products
`Just for thelrecord by A. D. Foster
`APPOINTMENTS VACANT
`
`INDEX TO ‘ADVERTISERS
`
`showing the
`Front Cover,
`medium wave aerial at Radio-
`landia, Comayagua. Honduras,
`introduces the article on edu-
`cation by radio in that country
`(page 57).
`Photographer Paul Brierley
`
`"IN OUR NEXT ISSUE
`
`tester.
`Electrolytic capacitor
`Enables the value of an electro-
`lytic capacitor to be measured
`automatically and the result
`_ displayed directly by meter.
`v Leakage is also indicated.
`
`Two-stage linear amplifier. A
`discussion of
`the design of
`solid-state 50W and 300W
`linearamplifiers for the h.f. band
`(1.6-30MHz).
`
`look
`the '80s, ' a
`Radio in
`forward to sound receiver design
`and the ideal set of the future‘ by
`the BBC's chief engineer of radio
`broadcasting.
`
`Current issue price 35p, back_ issues (if available) 59 . at‘ Retail and Trade’ Counter. Paris Garden.
`London SE1. By post. current issue 55):, back issues (1 available) 50p. order and payment to Room 1_1,
`Dorset House. London SE1 9LU.
`'
`-7Editorial & Advertising offices: Dorset House. Stamford Street. London SE1 91_U.
`‘Telephones: Editorial 01-261 8620: Advertising 01261 8339.
`Telegrams/Tclcx. Wiworld Bisncspres 25137. London. Cables. “Ethaworld. London SE1.
`Subscription rates: I year: £7.00 UK and overseas ($18.20 USA and Canada). Student rate: '1 year, £3.50
`UK and overseas ($9.10 USA and Canada).
`I
`Distribution: 40 Bowling Green Lane. London ECIR ONE. Telephone 01837 3636.
`Subscriptions: Oakfield House. Pcrrymount Rd. Haywards Heath. Sussex RH16 3DH. Telephone
`_ 0444 59188. Subscribers are requested to notify a change of address. © 1,p_c. Business press Ltd, 19-17'
`
`ISSN 0043 6062‘
`
`imlmuanii amm
`“vets mnmm
`
`PMC Exhibit 2068
`Apple v. PMC
`IPR2016-00753
`Page 2
`
`

`
`Wireless World, April 1977
`
`VIEWDATA
`
`3 ~— Operation of thesystem: terminals and codes.
`
`by S. Fedida, B.Sc. (Eng_), M.Sc., F.l.E.E., ‘A.C.G.l. Post Office Research Centre
`
`is
`the cradle. Once contact
`side of
`established, the computer transmits a.
`first frame, which requires the user to
`enter a user number. When this has
`been done Viewdata offers the first
`index (shown in the February issue, p.
`32).
`The action is now transferred tomthe
`keypad. On this the user keys—in his user
`number and any further responses.
`Suppose the user’ wishes «to obtain
`information about entertainment acti-
`vities for a given day of the week. The
`
`.
`
`Fig. 1.,Overall picture of connections in
`Viewdata, showing the telephone
`system at the top and the home and
`office terminal at the bottom.
`
`user may enter the entertainmentpage
`direct by keying “3230g. An example of
`one of the pages in the entertainment
`sequence was Fig. 6 in the February
`issue.'ln later models of the terminal,
`use is made of the calling key on the
`keypad. This calls the Viewdata com-
`puter automatically and switches over
`to the modem without
`the user’s
`intervention. The keypad may then be
`used as previously.
`-The design philosophy of Viewdata
`which has been dealt with in the first
`'"‘fiatabanks
`
`Telephone
`exchange
`
`Viewdata
`computer
`
`Strowger,
`crossbar ’
`or TX E
`exchanges
`
`75 bits / sec
`
`/'./
`
`1200 bits/sec
`
`Local telephone
`exchange
`
`‘\_—‘/id
`other
`customers
`
`Part 1 of this series, in the February
`issue. gave an introduction to View-
`data. with mentions of earlier sys-
`tems. Part 2, in the March issue, dealt
`mainly with applications. This article
`‘now describes the overall arrange-
`ment of the system, the codes used
`and the Viewdata terminal.
`
`Fig. 1 gives ‘an overall view of ‘a"Viewdata
`connection. The home terminal, shown
`at the bottom left hand side, comprises a ~
`domestic television set, a telephone
`instrument, a Viewdata adaptor and a
`keypad. The actual assembly is shown
`in Fig. 2. Two types of keypads proposed
`are shown in Figs. 3 and 4. The basic
`keypad is Fig. 3; this provides the ten
`numerals, ‘and ; symbols and keys for
`automatic dialling, if installed. Fig. 4 is
`an alphanumeric keypad. This contains
`in addition to the above, the complete
`upper case alphabet, punctuation marks
`and symbols like £,%,/, arithmetic and
`algebraic symbols and cursorrcontrol
`characters. A typical Viewdata terminal
`for the office,
`the Viewdataphone,
`is
`shown schematically at
`the bottom
`right hand side of Fig. 1. This consists
`of
`a Viewdata terminal and a
`self-contained telephone instrument. A
`typical Vie-wdataphone was shown in
`the March issue. The Viewdata com-
`puter is shown at
`the top of Fig.
`l,_
`notionally connected to a variety of.
`data banks, either direct or through the .
`switched telephone network.
`As mentioned in the February issue‘.
`communication between the terminal
`and the Viewdata. computer is at a rate
`of 1200 bits/s from computer to termin-
`al and 75 bits/s in the opposite direction.
`More details of this arrangement will be
`given later.
`*
`In order to establish a connection to
`the Viewdata computer the user dials
`the telephone number of the computer
`as for a normal telephone call. When the
`connection is established the computer
`generates a high pitched tone (fre-
`.'quency l300Hz) which is heard in the
`telephone receiver. The user
`then
`presses a button marked “data" on the
`telephone set, which switches the
`telephone line from the telephone set to
`a modem (modulator-demodulator).
`The telephone receiver is then set by the
`
`~
`
`PMC Exhibit 2068
`Apple v. PMC
`IPR2016-00753
`Page 3
`
`

`
`Wireless World, April 1977
`
`except for the actual codes transmitted
`over the line, where a slight change is
`made to comply with International
`Standards Organization recommenda-
`tions.
`The table of codes used for Viewdata
`is shown in Figs. 6, 7 and 8. Fig. 6 shows
`the joint Viewdata and teletext codes
`for alphanumeric characters only. This
`differs from earlier versions in the
`following characters:
`Column
`
`Is now’
`(—'
`1/2
`_.
`-
`
`Was
`:
`\
`3
`_
`
`‘.
`
`1 1
`
`Row
`ll
`12
`l3
`15
`0
`ll
`‘i2
`13
`
`\l\l\l\lG§UIU1UlU1
`
`two parts of this article referred Lu the
`need to keep the cost of Viewdata down
`v to very low levels, both on the terminal
`side and on the computer usage side.
`Indeed, unless the cost of using the
`computer facility is kept substantially
`below that of using current computer
`time-sharing systems, the whole project
`may not become viable. This therefore -
`postulates the use of a distributed
`computer system, so arranged that the.
`majority of users may have access to a
`nearby computer centre, at the cost of a
`local telephone call for the connection
`plus a correspondingly modest charge
`for the use of the computer and the
`information provided.
`The resulting network is typically as
`shown in Fig. 5. Users are within a local.
`call distance of their computer centres,
`shown as rectangles. A cluster of local
`computer centres is grouped under the
`control of a regional centre for the
`purpose of data gathering and distribu-
`tion. A national data centre controls the
`operation of
`the whole system and
`distributes to each regional centre new
`information, news and data updates.
`Regional centres also accept informa-
`tion of regional or local interest and
`distribute this to the local centres.
`
`The Viewdata terminal
`:Display format. The display format of‘
`Viewdata is identical with that of
`teletext, i.e. a page consists of 24 rows of
`40 characters each, each character
`being generated by a 5 X 7 matrix with
`upper and lower case, character round-
`ing, graphics symbols and colour. Thus:
`a great deal of the electronics in a
`terminal may be common to Viewdata
`and teletext,
`the differences being
`primarily concernediwithuthe addition?
`all functions needed in Viewdata, the
`‘different modes of transmission appli-
`cable to these two systems and the
`different contraints appertaining to the
`different communications media
`involved.
`In the case of Viewdata the data
`K enters the terminal via the telephone
`line at relatively low speed, and, as the
`probability of data corruption is quite
`low, little is needed for the purpose of
`error detection and correction. Indeed,
`extensive Viewdata tests have been
`
`A Fig. 2. Home terminal for Viewdata,
`with television sentélephone (right)
`‘and keypad on the table.
`
`A Fig. 3. Basic keypad used in a Viewdata
`terminal,providing ten numerals and a
`few other keys.
`
`carried out over the past two years from
`a large number of centres in the UK and
`on the Continent. In all these tests the
`public switched telephone network was
`used to connect up to the experimental
`Viewdata system based at Martlesham,
`near Ipswich, and transmission diffi-
`culties have been very rare.
`The_ character codes used for View-
`data and teletext are also identical,
`
`Regional data, news
`
`Regional
`
`Local_
`computer 3
`
`Local
`computer 2
`
`14
`Note: The top, left~pointing, arrow is used as
`an assignment statement; the lower, right-
`pointing, arrow means “go to”; and the sign :
`is used as a terminator and for special
`functions. Note also that
`the arithmetic
`operator >< (multiply) used in Viewdata is
`shown as 3: (lower case x), while the minus
`sign (—) is code 2/13 and the exponentiation
`sign is code 5/14 shown as -.1‘.
`'
`‘
`
`Fig. 4. More elaborate, alphanumeric,
`vieeypad with a variety of other symbols.
`
`V Fig. 5. A distributed Viewdata network,
`showing local computers, regional
`centres and national data centre.
`
`‘
`National
`data
`
`National data,
`news
`'
`
`LOCEH
`C°""P"‘eV‘l
`
`Regional clusters
`100,000 customers each
`
`Local
`computer 2
`
`computer 3
`
`PMC Exhibit 2068
`Apple v. PMC
`IPR2016-00753
`Page 4
`
`

`
`Wireless World, April 1977
`
`b
`
`1
`
`1
`
`t
`
`.
`
`.
`
`.
`
`.
`
`EEIIIHH
`o
`44000
`
`(DW\lO)Ul-AWN-‘O
`..a_.01.110
`
`3
`fi
`_.(J
`
`S1
`
`,§‘_Nv<_>¢S<,l:.—rm-3.01:
`
`/\»uoa4puJ\lO1Ul.b~uIM-‘O
`
`Oz§I‘7t4.-«IG7'nrr1U«0(n>
`
`;;;t—>¢$f_~<><§<«:—Imz1o
`
`.=-u:_-«rp‘n.ncrn-
`o:3.—,,._._
`
`__.4_.oaoo_._.
`
`A Ezg. 6. Codeisfof alphanumeric chcirrzcrs éiizyf
`as used in both Viewdata and teletext.
`
`.
`.
`.
`Fig. 7 shows the graphics and control
`characters use in teletext, as at Sep-
`tember 1976*, the conventions being as
`before, that is:
`-
`’
`1. All character rows start
`in the
`“steady”, “alphanumeric white” and
`“unboxed” condition without control
`Charactem
`2. Control characters shown are dis-
`
`(SO)
`1110
`(51)
`’
`.
`'1 1
`1
`1
`’
`_
`._\
`Fig. 7. Codes for graphics used U1‘ teletext.
`.
`
`.
`
`
`'—
`~
`’
`
`I
`
`oo o o p
`
`0 0 Q 1
`
`0 0 1 0
`
`0 0 1
`
`1
`
`‘
`
`0,‘ ° °
`‘
`O 1 O .1
`
`01 1 o
`0111
`
`1 0 O 0
`
`1 o o 1
`
`1 O 1 O
`.1 o 1
`1
`
`v
`
`1
`1
`
`1 ° °
`1 D ,
`.
`
`_
`
`‘
`
`(NUL)
`alpha"
`ran '
`’ alpha“
`QPEEU
`alpha”
`yellow
`alpha"
`‘ blue
`al ha”
`riiagenta
`alpha” '
`Cyan b
`alpha”
`white
`flash
`
`steady
`
`endgaox
`start box
`n
`”fi2l‘§fii
`double
`height
`
`(_DLE)
`graphics
`red
`- graphics
`' QPCQH
`graphics
`yellow
`'g,r‘a’phics
`blue
`'aph“ 5
`_g'i'nagIeCnta
`graphics
`‘cyan
`graphics
`white
`conceal
`display
`contiguous
`graphics
`
`separated
`9'aP"'F5
`(Esc)
`black
`background
`new
`-
`background
`h°'d
`.
`graph“
`resffff.-cs
`
`lIH3EHEW%%3IlEl5%%v'"IFFFEEfitl-B
`[5-tntlmtI5u3ai5i'ea53eIn5iu55u5_u§|u3u35u11
`
`_
`
`0 o 0 1
`
`o
`
`o
`
`-
`
`0 0
`
`0 °
`
`0 1
`
`0 ‘
`
`‘ °
`10-
`
`1
`
`1 O
`
`13
`
`14
`
`Y\)A.ru
`
`fi
`
`(.0-0.W.
`
`lIEEEE[llLliEfi[ElE£EIFl'EE55F|'l]E£lLljl"‘fl[lL‘
`
`nelivusnaailraieiaeaatinusaaaaaaahauirjaséf
`
`alpha" "
`red
`aloha"
`green
`alpha“
`yellow
`alpha"
`blue
`a|p|-1;"
`magenta
`alpha"
`cyan
`alpha"
`White
`
`'
`
`graphics
`red
`graphics
`SW9“
`Q"-‘=|Dhics
`Yellow
`graphics _
`blue
`graphics
`m39°"‘*3
`' graphics
`cyan
`graqhics
`White
`
`.
`
`flash
`steady
`
`end box
`start box
`
`normal
`height
`double
`> height
`
`L
`
`Ccg‘s::':‘y
`contiguous
`graph‘-C5
`separated
`graphics
`
`black
`background
`new
`background
`hold
`graphics
`release
`graphics
`
`cursor
`home
`152
`
`'
`
`1
`
`played as spaces, but control whether
`alphanumeric or graphic characters are
`‘displayed andwhat colour is used.
`3. Alphanumeric characters in columns
`4 and 5, i.e. all of the upper case letters
`I
`and a few others, may be displayed next
`to graphic symbols without an inter- F:
`veal]/lliligljglligeintervening space conven—
`b7 b5b5b" b3b2b'
`Bits
`tion following a control character is
`0 O 0 ;l
`essential in teletext, it has been accept«
`‘
`ed in Viewdata for the sake of unifor-
`mity, although it is not really essential
`and imposes undesirable constraints on
`the page format.
`V
`Additional control characters have
`recently been added to teletext
`to
`provide enhanced display facilities. The .
`"intervening space” convention is
`somewhat modified and made less
`onerous, although not all its undesirable
`effects are eliminated.
`The new control characters, which
`may be applied equally in Viewdata are
`in four groups:
`Contiguous/separate git-aphics.V‘Ci6d§'l79
`and 1/10 in teletext, 5a/9 and 5a/10 in
`Viewdata. This provides the choice of
`graphics symbols filling the whole of a
`character rectangle, or only six discrete and
`‘separate dots.
`Normal height/double height. Codes 0/l2 '
`and 0/13 in teletext, 4a/12 and 4a/13 in
`Viewdata. This provides for the optional
`display of alphanumeric characters in the
`standard size, i.e. within the normal char-
` - l
`“"Broadcast Teletext Specification. Published
`jointly by the Broadcasting Corporation, lnclepen-
`dent Broadcasting Authority and British Radio
`Equipment Manufacturers Association.
`
`1
`
`1
`
`1
`
`15
`L—'
`Fig. 8. Control and graphics codes used in‘VieWdata.
`
`-IiI5I3iIIiH:a:au'I5:l:’un'3I:If|.:.iI35E:£
`
`‘l
`
`IWEAI‘3P@ii'_lii3flii5ii1‘REElEili£L
`
`
`:-I’.
`
`‘incur:-itlaiujzaiiiaaiai-.irmii-an-.iat+1triasu:ii:a;o—
`
`:7‘
`
`«
`
`|_-EEEHlifili!lE3flvEm'll3IElP.'li[filE
`
`Page 67
`
`PMC Exhibit 2068
`Apple v. PMC
`IPR2016-00753
`Page 5
`
`

`
`58
`
`acter rectangle or stretched vertically to
`double height, the width of each character
`and the intervening spaces between char-
`acters remaining the same.
`
`Black background/new background. The
`background colour of the character rectangle’
`is normally black. Whenever
`the new
`‘background control character 1/13 in tele-
`text or 5a/13 in Viewdata occurs, the display
`colour then obtaining is adopted as the new
`background colour.
`Hold graphics/Release graphics. Codes 1/14
`
`and 1/15 in tclctext, 521/14 and 5a/15 in
`Viewdata. This allows a limited range of
`abrupt display colour changes in a row
`whereas normally there is at least one space
`between rectangles with different display
`colours in the same row.
`
`The graphics and control characters
`in Viewdata are show in Fig 8, but
`before these are looked at in detail, the
`use of a cursor in Viewdata should first
`be_explained.
`
`Wireless World, April 1977
`
`Cursor. The cursor in Viewdata is a
`symbol which shows up on the display
`as a bright rectangle, filling’the space of
`an upper case alphabetic character. It
`may be switched on and off, as required.
`by a switch on the terminal or onvthe
`keypad, or by remote control from the
`computer. It may also be moved any-
`where over the display either manually
`by using special keys on the keypad or
`by remote control from the computer.
`The cursor has many functions.
`
`[———',__.
`‘g mqgqmqq
`0000
`
`I
`
`0 O O 1
`C
`0
`
`V
`
`» alpha“
`V
`red.
`alpha"
`green
`alpha"
`yellow
`alpha"
`blue
`alpha“magenta
`alpha"
`cyan
`alpha"white
`flash
`
`steady
`
`end box
`start DDX
`
`normal
`height
`double
`height
`
`E$$flElEEflElflB5B55Efl§lEIEHflEEl
`
`ZT‘EI3PWlEEilfi‘i!!E53lEIil9ilEEESilo
`
`graphics i
`red
`grapnics
`green
`graphics
`yellow
`grapnlcs ‘
`blue
`graphicsmagenta
`graon ics
`cyan
`grapncs
`white
`conceal
`display
`contiguous
`graphics
`'>epar‘a1.ed
`graphics
`
`black
`background
`new
`background
`hold
`graphics
`release
`graphics
`
`$EEE$l:Hljn5EE3EEEmFl'Fl V
`
`cursor
`home
`
`l
`
`-1!
`vN
`
`T<Fg;9cnmmew
`set of Viewdata
`Codes: columns
`2a, 3a, 6a and 7a
`for graphics and
`columns 4a,and
`5a for the
`controls.
`
`—EZEEE,EIu’jflI!iI5E3I':IlEiFPlI"
`
`V Fig. 10. Blocle
`diagrams of (a) a
`Viewdata
`terminal and (b)
`a teletext
`terminal,
`showing video
`connections to
`the television set.
`
`COLOUR TV RECEIVE
`
`Electronic
`
`Electronic
`
`O“iP“f5
`
`VIEWDATA '
`DECODER
`
`INTERFACE some
`
`Outputs
`
`TEL T XT
`DECODER
`E E
`UNIT
`
`I
`Switch control
`
`INTERFACE BOARD
`‘
`
`(bl
`
`PMC Exhibit 2068
`Apple v. PMC
`IPR2016-00753
`Page 6
`
`

`
`VVireless World; April 1977
`
`69
`
`TELETEXT
`DECODER UNIT
`
`(b)
`VIEWDATA
`DECODER UNIT
`aw
`
`Line input
`
`Basically it gives a visual indication of
`the position on the screen at which the
`next character sent by the computer
`will be displayed. When the computer
`sends a new page of information to the-
`terminal,
`it first sends a codewhich
`returns the cursor, whether visible or
`not on the display,
`to the “home”
`position which is at the top left—hand
`side of the display. Thereafter, as each
`character
`is entered,
`the cursor is
`moved one character position to the
`right. The position of the cursor,
`whether this is switched on or off, is
`recorded by two counters, a character
`counter and a row counter, which
`maintain at all times a knowledge of the.
`position at which the next character is
`to be displayed (and entered on
`memory). Thus we talk of the cursor as
`it it were a real entity, whether or not it
`is displayed.
`By moving the cursor by means of the
`controls available (see below),
`the
`computer may position it to where the
`next character is to be entered. Thus it is‘
`‘not necessary to send a series of spaces
`where one or more blank lines are
`required, or where a row of characters is
`shorter than the full length of the line,
`‘ The cursor also enables the computer to
`overwrite a portion of a display without
`having to first erase and retransmit the
`whole page.
`The cursor may also be used at<the
`terminal for editing purposes, e.g. when
`composing messages or doing calcula-
`tions, or to point at a feature of the
`display it is desired to manipulate. In
`this context the cursor is a powerful ,
`= communication channel between com- ,
`
`‘
`
`Fig. 11. Block diagrams of (a) a teletext
`terminal and (b) a Viewdata terminal,
`showing r.f. (u.h.f.) connections to the
`television set.
`
`. .
`
`'
`
`,
`
`BS
`
`0/8
`
`0/9
`
`0710 L1:
`
`0/11 VT
`0/12 FF
`
`puter and user which resembles‘ a
`pointer (but more about this later).
`Control characters in columns 0 and 1
`must comply with ISO7 for line trans?
`mission and so far 15 have been
`allocated. Additional characters in the
`same columns may be allocated in
`future as more facilities are included. '
`The control characters wnicn have so
`far been allocated in the experimental
`system undergoing pilot trials are:
`Coll Name Function
`.
`.
`.
`TOW .
`.
`'
`.
`0/1 NUL None-used for timing purposes
`0/5 ENQ Code sent by computerto
`.terminal to initiate automatic-
`terminal identification
`Baclrrspace. Moves cursor one
`character position to left
`1-1'1‘ Horizontal
`tao.
`ivlo\'/‘es cursor
`' "one ._character position to right
`Line feed. Moves cursor one line
`position down
`Vertical tab. Moves cursor one
`line position up
`Form feed. Erases screen and
`moves cursor to top left hand
`side of screen (position 1)
`,
`Carriagereturn. Moves cursor to‘
`first_1J9sition on same line
`'
`Combinations
`of these char:
`actors will be‘
`used to switch
`. on tape record
`ders and’ hard”
`copy
`devices
`remotely
`
`‘O/13 CR
`
`1/1 DCl Device
`controll
`l/2 DC2 DeViC9
`>
`control2
`~13.
`DC3 Device.
`control 3
`
`1/ 9
`
`1/4 - DC4 Device control 4. Used to switch
`off both tape recorder and hard
`copy unit
`l/8 CAN Cancel. Used to delete line of
`character. This code is used only
`from terminal to computer
`ESC_ Escape. Used to in‘dicate to
`terminal that the character _
`following is from another set of
`control codes (in this case the
`control code set 2a 'toV_7a of
`colours or graphics)
`Horne. Returns cursor to
`character position 1 on screen
`(top left hand side)
`
`.
`
`Graphics characters. The graphics’ and
`colour control characters for Viewdata
`are shown in Fig. 8 columns 221, 3a, 6a, 7a
`for graphics and 4a and 5a for the
`controls. For line transmission the
`control characters of 4a and 5a are
`always preceded with ESC (code l/ll).
`On receipt of this code the terminal
`reverses the polarity of bit 7 from 1 to 0,
`thus restoring compatibility with tele-
`text and places the characters in store.
`The graphics characters in columns
`2a, 3a, 6a and 7a are fully compatible
`with teletext and are treatedin the same
`way when displayed. The complete set
`-of Viewdata codes is shown in Fig. 9.
`
`Block diagram of terminal. A block
`diagram of a Viewdata terminal
`is
`shown in Fig 10 (b). This shows the
`interconnection between the Viewdata
`decoder and the video amplifier of the
`colour tv receiver. An interface board
`contains the electronic switch which,
`provides
`the changeover
`from tv
`.reception to Viewdata. The input to the
`Viewdata decoder unit is, of course, the
`‘telephone line. By contrast Fig 10 (a)'
`shows the teletext decoder connections
`(Wireless World, December 1975, pp-.
`563-566). The input
`to the teletext
`decoder is obtained from the i.f. input.
`Fig ll shows a similar set of c(mneL:~
`tions where the entry to the television
`set for display purposes is the‘ aerial‘
`socket of the tv receiver. In Viewdata
`only (b) a u.h.f. modulator has to be
`added,‘ whereas” For_feletext
`(a) an‘
`additional tuner and i.f. strip must be‘
`provided. Hence the considerably
`greater attraction of a built-in decoder
`in the case of teletext.
`
`(To be continued)
`
`-
`
`’ 9
`
`The journal you like
`Wireless World's average circulation
`' last year, was up 4,604 copies to 69,220
`per month, according to the Audit
`Bureau of Circuiations. Overseas
`readers, in countries from the USSR and
`USA to the Falklands and Seychelles,
`bought 21,000 of these.;__Qn“average, for
`the past eight years 200 more readers
`have joined our’ circulation each month.
`
`Page 69
`
`PMC Exhibit 2068
`Apple v. PMC
`IPR2016-00753
`Page 7