`
`
`
`IPR Petition - USP 5,887,243 coe
`
`New isotope
`scanning,
`iN
`technique
`
`New Zealand §NS1.40
`NorwayKr. 10.00 inel. moms
`Partugal Esc, 40.00
`South Africa R. 1.10
`Spain Ptas. 80.00
`Sweden Kr. 6.90 inc!. moms.
`U.S.A. $1.50
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`PMC Exhibit 2069
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`Page 1
`Page 1
`
`
`
`
`
`
` wireless _
`‘world
`‘Electronics, Television, Radio, Audio
`
`
`.No. 1497
`MAY 1977=Vol83.—s
` Contents
`
`
`
`Front cover is a.print produced
`
`
`
`35 Surround souid — time to consolidate
`by the Tomoscanner, described .
`
`by John Dwyer on page 82 of*|-
`
`36.Radio in the ’80s by Duncan MacEwan ,
`
`
`this issue. Print supplied by J. & .
`41 BBC Matrix H by P. A. Ratliffe and D. J. Meares
`P. Engineering (Reading) Ltd.
`
`46 World of amateurradio
`;
`47.Automatic electrolytic tester by A. Drummond-Murray
`
`50 Variomatrix adapter for System 45J and Matrix H
`
`
`
`by Michael A Gerzon
`.
`:
`:
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`
`
`
`,
`51 HF. predictions
`
`
`52 Logic design — 4 by B. Holdsworth and D. Zissos
`
`_55 Viewdata — 4 by S. Fedida
`,
`60 Letters to the editor
`
`
`
`
`
`
`
`
`
`
`HadHarta,ascndand:enedmene)Lrcaal
`
`
`
`
`
`Mobile radio planning
`Do-it-yourself biofeedback
`Audibility of phase effects
`63 Newsof the month
`
`:
`
`Annan and technology
`/
`ITU Conferenceresults
`British Rail high-speed track measurements
`67 Two-stage linear amplifier by Helge Gronberg
`71 Power semiconductors — 2 by Mike Sagin
`-79 Circuit ideas
`Linear voltage/frequency converter
`Pulse-counting frequency comparator
`Op-amp poweroutput stage
`82 New tomography machine by John Dwyer
`85 Newproducts
`oO
`APPOINTMENTSVACANT
`INDEX TO ADVERTISERS
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`Current issue price 40p, back issues(if available) 50p, at Retail and Trade Counter, Paris Garden,
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`London SEI. By post, current issue 5p, back issucs (if available) 50p, ordcr and payment to Room 11,
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`
`IN OUR NEXTISSUE~
`Loudspeakers and rooms. A
`- discussion by James Moir of the
`‘interaction between the output of
`a loudspeaker and the acoustic
`“performance
`of
`the
`listening
`room.
`
`‘Matrix H decoding. Circuit
`details of a matrix H variable
`matrix decoder, a developmentof
`Sansui's Variomatrix, for use with
`experimental
`surround-sound
`programmes.
`,
`
`Using a microprocessor. The:
`start of a series of articles on the
`design of a typical processor-bas-
`ed control system, starting with
`no assumptions of prior knowled-
`ge on the reader's part.
`
`ISSN 0043 6062
`
`
`Basal——ThereseaadHarrie
`
`
`Press Apaocnes
`Faemationat Business
`
`
`
`
`Page ti
`ene
`
`PMC Exhibit 2069
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`Apple v. PMC
`IPR2016-00753
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`Page 2
`Page 2
`
`
`
`Wireless World, May 1977
`
`Viewdata
`4 _ The Viewdata terminal in more detail
`
`by S. Fedida, B.Sc.(Eng.), M.Sc.,-F.LE.E.,A.C.G.1,
`
`Post Office Research Centre
`
`55
`
` i
`
`t
`
`{ i
`
`1
`unit
`
`.
`|
`unit
`10 unit code
`6 bit character
`10110011 = character M
`
`Parity bit (odd parity)
`
`Fig. 2. Transmission code used between
`a Viewdata terminal and the computer
`is an &-hit, 10-unit asynchronous code.
`
`_consists of an 8-bit code, the first 7 bits
`containing the information while the
`8th bit is a parity bit. Preceding each
`character is a start bit, with a stop bit
`terminating the character. The cha-
`racter lustrated in Fig. 2 is M, with odd
`parity. A 10-unit asynchronous system
`
`Fig. 1. Comparing the main sections of
`(a) a Viewdata decoderwith (b) those of.
`a teletext decoder
`
`was chosen for simplicity. It is clearly.
`not as efficient as a synchronoustrans-
`mission mode, in which characters fol-
`low each othcr without the intervention
`of start and stop bits, butit is simpler to
`implement and ts currently used by
`many time-sharing computer systems.
`In order to transmit this code over a
`telephone line, a modem (modulator-
`demodulator) is required. Essentially
`this device modulates the code on to a
`voice frequencycarrier, within: the
`speech band, thus obviating the pro-
`blems encountered with very low fre-
`quency transmission overthe telephone
`network. The modem also enables the
`go and return transmissionto take place
`
`A Viewdata decoder may be considered
`as being madeupofsix parts, as shown
`from left to right in Fig 1(a): a line
`isolation unit; a modem; a keypad; an
`input processor; a store (possibly
`r.a.m.); and an output processor. Indeed
`the breakdownoffacilities is very simi-
`lar to thatof teletext, shownin Fig. 1(b).
`This diagram also indicates that, apart
`from additional minorinterconnections,
`parts common to Viewdata andteletext
`are the store and. output processor.
`These are substantial components and
`therefore combined Viewdata/teletext
`receivers show important savings over
`two separate decoders for the two ser-
`vices. This is a slightly over-simplified
`picture but the situation will be clarified
`later.
`:
`Note however, an important differ-
`ence. The input circuits in Viewdata,
`up to and including the store are bi-
`directional, thus highlighting the inter-
`active nature of the system. On teletext
`the input circuits are one way only.
`
`Line transmission
`The transmission code used over the
`telephone line between the Viewdata
`termina] and the computeris at present
`8-bit, 10-unit asynchronous (or start
`stop); as shownin Fig. 2. Each character
`
`
`wore
`To tv
`Output
`Input
`processor
`processor
`display circuits
`
`
`Keypad
`
`
`Input
`processor
`
`(b)
`
`Output
`processor
`
`10 t¥
`a
`display circuits
`
`Page 55
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`PMC Exhibit 2069
`Apple v. PMC
`Apple v. PMC
`IPR2016-00753
`IPR2016-00753
`Page 3
`Page 3
`
`
`
`56
`
`Wireless World, May 1977
`
`:
`
`
`
`
`a
`D
`readscares
`1
`ot
`
`
`Nl
`
`Viewdata
`write
`address
`
`Poomodseee
`
`Teletext data
`%
`; CTT
`cca 7“
`rmmer eee Se Se = bata
`| Data
`|
`Teletext
`|
`selector
`=
`display
`|
`aaa/tisten | Fees
`a)
`r |
`unit
`i Viewdata acogSSiewdata,
`H
`1.
`1
`g
`ree wrt 1
`0 type
`Teletext address__
`t
`1
`V
`iM Y
`K
`
`
`
`
`, Random #
`access
` Data out
`“© Display : aS
`unit
`=
`
`memory
`
`
`‘simultaneously over the two-wire tele- -
`phoneline.
`Transmission rates selected for
`Viewdata during the present experi-
`mental phase are 1200 bits per second
`from computer to terminal and 75 bits
`per second in the reverse direction.
`In the computer-to-terminaldirection
`as high a transmission rate as possibleis
`‘desirable in order to achieve a fast
`picture build-up. 1200 bits per second
`waschosento fit in with a well tried and
`readily available modem.Forthe majo-
`rity of Viewdata displays, consisting for
`example of mainly alphanumeric cha-
`-Yacters, the picture build-up is much
`faster than can be read by the user, and
`hence quite adequate from this point of
`view. Where, however, large uniform
`areas of graphics are displayed, the
`build-up. may appear rather slow (the
`display shows repetitive information),
`and improvements to the build-up in
`this case may be obtained by using
`special means. But in general the
`additional complexity is not really
`worthwhile.
`In the direction from terminal to
`computer the bit rate of 75 bits per
`second (7.5 characters per second) is
`quite adequate for hand keying.
`The frequencies used in line trans-
`mission are as follows:
`Forward channel:
`(from terminal
`to computer)
`
`binary 1=390 Hz.
`binary 0 =450 Hz
`
`Return channel:
`(from computer
`to terminal)
`
`binary 1 = 1300 Hz
`
`binary 0=2100 Hz
`
`When no data transmission is taking
`' place on the line the terminalis trans-
`mitting continuously at 390Hz and the
`computer at 1300Hz. These tones are
`used in the mademsat either end of the
`line to. provide an indication of conti-
`nuity, which as we shall see below is of
`* some importancein the operation ;of the
`whole system.
`When data is being*transmitted the
`
`Fig. 3. Simplified block diagram of a
`Viewdata terminal, with adaptation to
`teletext shown in broken lines. The
`numberand bar on certain connecting
`lines indicate that the line is carrying
`parallel information onthat number of
`wires.
`
`‘carrier is frequency modulated (fre-
`quency shift keying), between the
`binary 1 and binary 0 frequencies, the
`‘change being smoothed out to give a
`gradual transition between the fre-
`quencies.
`The transmission arrangement used
`at present is duplex, with ‘echoing’
`facilities provided from the computerto
`the terminal. In a duplex system trans-
`mission may take place in both direc-
`tions at once over the telephone with no
`mutual interference (hence, of course,
`the choice of frequencies). Characters
`keyed at the terminal arefirst trans-.-
`mitted by the modem to the computer
`and displayed only when they are
`“echoed” back. This arrangement gives
`some important advantages. First, it
`provides a measure of error detection,
`the user being aware of any corruption
`in transmission, errors in the computer
`or mis-keying errors, Secondly, duplex
`working also increases the user’s confi-
`dence in the working of thé system, as
`“echoed” characters provide a continu-
`ousindication that the whole system is
`in satisfactory order.
`“Echoing” from the terminal to the
`computer is not necessary. A parity
`check is sufficient to provide for the
`detection of the majority of. errors, the
`computer usually responding in these
`cases by requesting a repetition of the
`instruction. The computer also moni-
`tors continuously the terminalcarrier,
`thus ensuring that aline break is noted
`as soon as it occurs. This avoids the
`possibility of the user being incorrectly
`charged for using the system after the
`occurrence of a line interruption.
`
`Experimental Viewdata terminal
`The experimental! Viewdata terminal at
`presentin use is best introduced in two
`parts: (a) the data transmission unit,
`which deals with the Viewdata signal
`between the telephone line and the
`internal store, and (2) the display unit,
`which deals with the Viewdata signal
`between the store and display device.
`(the c.r.t. of a television set), As
`explained earlier, much of the display
`part is common with teletext.
`Atypical arrangementof a Viewdata
`‘terminal is shown in Fig. 3. There are
`four major units ‘as follows: the data
`’ transmission unit (1); the address selec-
`tor (2); the random access memory (3);
`and the display unit (4).
`The address selector (2) is the only
`unit which interconnects the input and
`output processors, essentially for the
`purpose of preventing mutual interfer-
`ence..Unlike the situation in teletext
`data is received at random .times from
`the. telephone
`line,
`completely
`unsynchronized with the operation of
`the display. It is therefore necessary to
`organise the access to the memory for
`reading out and display on the one
`hand,and writing-in incoming charact-
`ers on the other hand, without cross-
`interference. This function is carried
`out by the address selector. Thewrite
`address generated in the data transmis-
`sion unit (1) and the read address gene-
`rated in the display unit (4) are both
`available at the addressselector.
`.
`A mixed blanking waveform, also -
`generated in the display unit, indicates
`the times at which characters are
`required to be extracted from the
`memory for display purposesessentially
`during 40 microseconds of every line
`period, excluding blanklines at the top
`and bottom margins of the display.
`During these times incoming characters
`are made to dwell a little longer in an
`input character buffer in the data
`transmission unit and the address sup-
`plied to the memory is the read address.
`. At other times the write address is.
`
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`Apple v. PMC
`Apple v. PMC
`IPR2016-00753
`IPR2016-00753
`Page 4
`Page 4
`
`
`
`57
`two pairs of opposite polarity gas
`discharge tubes, each pair connecting
`one of the telephone wires to earth. It
`ensures that voltages originating from
`the terminal are limited to safe values
`before entering the telephonenetwork.
`It also containsfuses,in series with each
`telephone wire and on either side of the
`gas dischargetubes,to limit the current
`flowing. The gas discharge tubes have a
`striking voitage of about 150V, to avoid
`breakdown in the presence of ringing
`tonesoriginating in the telephoneline.
`Following the isolator is the modem
`. control unit, which contains a relay
`operated by the “data” button on the
`telephone: When this button is
`depressed it switches the telephoneline
`from the telephonereceiver to. a hybrid
`transformer within the control unit.
`This separates the go and return chan-
`nels connected to the modulator and
`demodulator respectively.
`The incoming Viewdata signal is
`superimposed on an f.s-k. (frequency
`‘shift keying) carrier, binary 1 corre-
`sponding to a frequency of 1300Hz and
`binary 0 to a frequency of 2100Hz. The
`incomin¥ carrier first gocs through two
`stages of bandpass filtering to eliminate
`unwanted signals. After this it is fre-
`quency shifted by 10kHz, thus becom-
`ing a frequency modulated carrier
`centred on 11.7kHz with a deviation of
`+400Hz, the modulation rate being
`1200 per second. Frequency shifting the
`carrier by 10kHz makes the demodula-
`tion process much easier by virtue of
`increasing the numberofcarrier cycles
`per modulation cycle.
`Theincomingcarrier is now applied to
`‘an unbalanced discriminator anda
`detector which extracts the data modu-
`lation. After filtering, amplification,
`squaring and level changing the data
`
`,
`
`} o
`
`ffers assembled characters to the con-
`trol codes decoder (9). It also triggers *
`the operation of the timing unit (10)
`which generates the necessary wave-
`forms used throughout the data trans-
`mission unit. The control codes decoder
`recognises the special control charact-
`ers used in Viewdata,initiates the cor-
`responding control functions and
`enables the memory (8) to. store the
`‘appropriate characters. It also controls
`the memory address unit (11), which
`maintains a‘record of the addresses.at
`which incoming characters are to be
`stored and instructs the terminal iden--
`tifier (12), to generate the automatic.
`identification code in reply to an
`enquiry signal receivedfrom the View-
`data computer.
`The transmission control unit,. the
`timing unit and the page transmission
`unit (7) together control the transmis-
`sion of a complete page from the termis ~~
`nal to the computer. The keypad unit
`(13) generates and encodesthe terminal
`responses and outputs these direct to
`the modem, for transmission to the
`computer.
`The data transmission unit operates
`in two different modes: reception mode
`and transmission mode.
`
`_
`
`Reception of Viewdata signals
`Isolator and modem. The Viewdata
`signal enters the terminal from the
`telephone line, after passing through
`the isolator. This may consist simply of
`
`Wireless World, May 1977
`
`switched to the memory. The address
`selector also notes the coincidence be-
`‘tween the read address and the write
`address when it delivers a pulse to the
`display unit to initiate the generation of
`the cursor display (see Part 3).
`Shown also in Fig. 3 in broken lines,
`are the units required for interfacing
`Viewdata with teletext. In a receiver
`already fitted with a teletext decoder,
`one additional unit is required: the data
`selector (5), while the Viewdata display -
`unit may be dispensed with and the
`teletext display unit (6) used instead.
`The connections required are shown
`also as broken lines. A: Viewdata/tele-
`text switch unit (7) is also shown. This
`sets data and address selectors to
`Viewdataor teletext as required.
`,
`In the teletext mode the address and
`data seléctors switch the memory to the
`teletext. input circuits, while in the
`~Viewdata mode the memory is available
`to Viewdata. The read address,
`however, is now provided by thetele-
`text address, which scans the memory
`during the mixed blanking period.
`
`Data transmission unit
`The data-transmission unit is shown in
`more detail in Fig. 4. This consists of a
`line isolator (1) and a modem (2, 3, 4),
`the last-mentioned including a modula-
`tor (4) which transforms -the outgoing
`data stream to a voice frequency signal,
`a demodulator(3) which accepts a voice
`frequency signal from line and extracts
`the data stream from it, and a control
`circuit (2) which switches the connec-
`tion of the telephone line to the tele-
`phonereceiver or to the modem...
`The transmission control unit (6),
`which is synchronized by the clock unit
`(5), accepts the demodulated data in
`. serial form, checks character parity and
`N
`
`Fig. 4. Data transmission unit at
`Viewdata terminal. The numberand.
`bar on certain connecting lines
`indicate that the line is carrying
`parallel information on that number
`of wires.
`
`Memory
`(8)
`
`s
`
`Memory
`address
`
`
`
`
`(11)
`
`
`
`
`2-wire
`Data
` switch
`
`
`line
`
`
`
`
`Control
`unit(2) eo
`
`
`
` Transmission
`
`
`
`Carrier
`fail
`
`Inhibit count
`1MHz clock
`Reset character
`Reset row
`
`Up/down
`Disable character
`
`Device
`control
`latches
`
`Demodulator
`
`Modulator
`(4)
`
`keyboard
`. encoder &
`register
`
`
`
`Character
`shift
`
`:
`
`LoeKeypad (13)| J
`
`:
`
`Load RDA”
`
`
`tlunit:
`
`Page
`
`
` Terminat
`
`transmission
`identifier
`
`(10)
`(12)
`
`
`wd
`
`
`
`Page 57
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`PMC Exhibit 2069
`Apple v. PMC
`Apple v. PMC
`IPR2016-00753
`IPR2016-00753
`Page 5
`Page 5
`
`
`
`58
`
`signal is fed out to the transmission
`control unit at a level of —6V for a
`frequency of 1300Hz (binary 1) and
`+6V for a frequency of 2100Hz (binary
`0).
`The transmission contro! unit. The
`transmission control unit accepts data
`in serial form and, using a sampling
`technique controlled by the clock gene-
`rator, recognisesthe start and stop bits
`of each 10-bit character sequence, and
`stores each character in a temporary
`buffer. This completed, it signals the
`event to the timing unit, and control
`codes decoder,i.e. that a character has.
`been received and is available for
`transfer at the input data highwayin a
`‘7-bit parallel form. °
`The transmission control unit also
`checks character parity and feeds out
`JPE (input parity error) to the control
`codes decoderif parity is found in error,
`
`.
`
`The timing unit provides a numberof
`waveforms which control the storage of
`characters in the memory.On receipt of
`a “data available” signal from the
`transmission control unit, it transfers
`the intended location of the received
`character from memory address to
`memory, enables memory to accept the
`character, clocks memory address to
`the next character position and resets
`the transmission control unit to indicate
`that the character received has been
`accepted.
`
`The control codes decoder accepts
`incoming characters from the input
`‘data highway, decodes the special! con-
`trol codes and initiates the appropriate
`‘actions as follows. The unit is “trans-
`parent” to all characters other than
`control codes, the former being ap-
`plied direct to the memory to be stored’
`therein.
`The control codes decoder performs
`the following functions. On receipt of?
`(a) Non storing characters such as NUL,
`CR, LF, BS, FF, etc. it inhibits their
`storage in memory. (Write disable to
`timing unit.)
`(b) BS, it causes memory address to_
`count down one character
`(c) VT, it causes memory address to
`count downone row.
`(ad) CR, it causes memory address to be
`reset to character address of.zero, leav-
`ing row address unchanged.
`(e) LF it causes memory address to
`count up one row.
`(f} FF it causes memory address to be
`reset to character address of zero and
`row address of zero. It also causes the
`complete content of memory to be
`erased by setting the code on the input
`data highway to “space” and entcring.
`this in the whole memory.
`.
`(g) ESC it causes bit 7 of the received
`character to be changed from 1 to 0,
`before storage,
`(h) DCi to DC4,it sets latches to. control
`internal devices.
`The control codes decoder, when
`receiving input parity error, substitutes
`
`character 7/15 for the character re-:
`ceivedin error before it is entered in the
`memory. The implementation of
`memory and memory address may be
`either in the form of a random access
`“memory ora series of shift registers. A
`Y.a.m. appears to lenditself to a rather
`simpler logic circuit than a shift register
`memory and because of this has been
`assumed in the description of the ter--
`minal.
`The memory address consists of
`characters and row counters which are
`controlled by the control codes decoder
`to indicate the address at which the
`next character is to be stored in the
`memory.
`
`.
`
`Transmission of Viewdata signals
`The transmission of Viewdata signals
`originates either from the keypad unit
`or the page transmission unit.
`The keypad unit controls a keyboard:
`connected in a cross-matrix of 5
`columnsand 9 rows,with a shift button,
`which together with the 45 keys, pro-
`vide a maximum of 90 codes, The basic
`keypad with which most of the View-
`data facilities may be used providesonly,
`12 codes, (0 to 9),
`* and #, with
`additional optional codes for automatic
`calling.
`In both cases the output of the key-
`board matrix is applied to an encoder
`which generates codes appropriate to
`the keys selected, serializes the bit pat-
`tern thus obtained, adds parity, start
`and stop bits and applies the resulting
`data stream directly to the modulator,
`under the control of an internal timing
`unit which generates the appropriate
`clock signals. Characters fed out are not
`displayed on the screen until they have
`been “echoed” backby the computer.
`The page transmission unit operates
`jointly with the transmission control
`unit and timing unit,and its operationis:
`initiated manually by a push-buttonon
`the terminal. This causes the page
`transmission unit to reset memory,
`address zero and enables transmission
`buffer empty (TBE) signal from the
`transmission control unit to start the.
`timing unit (using the page transmis-
`sion enables signal). It also inhibits the
`writing into memory, via write disable
`to timing unit.
`:
`On receipt of TBE, the timing unit
`generates a load signal to the transmis-
`~ gion control unit which causesthe latter
`‘to accept a character from memory,and
`to clock it out in serial form at 75 bits/
`second, complete with start, stop and
`parity bits, to the modulator. The timing
`unit also increases the memory address.
`count by one. When a character has
`been discharged from the transmission
`control unit, the next transmission
`buffer empty signal recommences the
`above cycle on the next character.
`When 960 characters have been sent
`out, the page transmission unit notes
`the fact and resets the terminal to the
`quiscent state.
`At the beginning of a Viewdata ses-
`sion the computer interrogates the
`
`Wireless World, May1977
`built-in termina] identifier. The control
`codes decoderinitiates the operation of
`this unit, which sends out an identifica-
`tion code to the transmission control
`unit. This code is transmitted to the
`‘modulator, complete with start, stop
`and parity bits. The operation is similar,
`to that of the page transmission unit
`except that the identification code is
`stored in the terminalidentifier.
`
`Display unit |
`is shown in more’
`The display unit
`detail in Fig 5. The function of the
`display unit is to generate line and
`frame-synchronising signal for the tele-
`vision raster, to decode the special
`display control characters for colour
`and graphics and to generate alphanu-
`meric and graphic symbols for display.
`As mentionedearlier, the display unit
`is nearly identical to the corresponding
`part in the teletext decoder. The major
`differences are in the line and frame
`synchronising generators and in the
`provision for the cursor, which is not
`required in teletext. With respect to the
`line and frame synchronising pulses,
`these are essential in a Viewdata-only
`receiver sincé it
`is required that the
`Viewdata service should be available at
`all times and not just during tv broad-
`casting hours; thus it is not always
`possible to rely on the presenceof tv line
`and frame sync to maintain theraster.
`The provision of line and frame sync
`pulses is also very useful in a combined
`Viewdata/teletext decoder, as indeed in
`a teletext-only decoder, since it is pro-
`vided in teletext that viewers should be
`able to store a page of information
`transmitted during tv broadcasting
`hours and to view it later at their con-
`venience, possible outside broadcasting
`hours.
`The display unit consists of a sync
`generator and memory scanner (1), a
`display control codes decoder (2), an
`alphanumeric character generator(3), a
`graphics generator (4), a character
`rounding unit (5), and an output unit
`(6).
`The syne generator and memory
`scanner generates line and frame
`synchronising pulses which are applied
`to the tv timebase generators, and row
`and character addresses which are
`applied to the r.a.m. via the address
`selector. The unit derives these wave-
`_ forms from an 8MHzcrystal controlled
`master oscillator followed by a chain of
`dividers, The extraction of characters
`from the memory andtheir display on
`the screen occurs at a rate of 1MHz,
`whichis derived directly from the 8MHz
`clock by a divide-by-8 circuit, a further
`division by 64 providing the line
`synchronizing pulses. There is a certain
`amount of flexibility in the choice of
`master oscillator frequency; a lower
`frequency, say 7MHz or 6MHz,giving 4
`wider character on the display, while.
`not being quite so demanding on the
`width of the video passband. The width |
`of individual characters may also be
`altered by adjusting the blank margins
`
`.
`
`-
`
`
`
`PMC Exhibit 2069
`PMC Exhibit 2069
`Apple v. PMC
`Apple v. PMC
`IPR2016-00753
`IPR2016-00753
`Page 6
`Page 6
`
`
`
`Display
`contro! codes
`decoder
`(2)
`
`cerriaerehy
`
`heelam
`to]
`Alpha
`generator >——
`(3)
`3):
`" Output 2
`
`Character
`rounding
`5
`
`Odd /even
`
`
`
`
`
`
`tate Tare]
`Graphics
`baat Sales
`8MHzIclock
`generator
`_
`to
`timebase
`(4)
`generator
`
`to the ‘left and right of the page on
`display. The choice of 8MHz hereis
`mainly of convenience to simplify the
`subsequent dividing circuits. The sync
`generator and memory scanned must
`also generate the mixed blanking
`waveform which provides the margins
`aroundthe display area. Thus every iys
`a read signal is applied to the r.a.m.
`which then feeds out the character
`stored at the location indicated by the
`row and character addresses generated
`. by the unit.
`The timing of the whole display unit
`must take into account delays occurr-
`ing in the r.a.m. and in the alpha-
`numeric character generators. These
`delays may be eachof the orderof 200 to
`600 nanoseconds, depending on cost,
`the faster unit obviously being more
`expensive. Thus in order to take up
`these tolerances and allow the cheaper
`units to be used, a 2us delay is allowed
`for from the instant a character is
`requested from memoryto the timeit is
`displayed.
`As in teletext, a row of characters
`consists of 10 television lines in each
`frame (20 lines counting the interlace),
`made up of 7-display lines and 3 spacing
`lines, each character space in the
`horizontaldirection consisting of 8 dots,.
`5 display dots and 3 space dots, the dots
`occurring at the 8MHzrate.
`As each character is fed out from the
`memoryit is transferred to the display
`control codes decoder which is pro-
`grammed to recognise the charactersin
`columns 0 and | of Fig 7 in the April
`issue, i.e. the special colour, graphics
`and other display control characters;
`provide blanking for the duration of
`these characters (since these are non-
`display characters); and inhibit
`the
`character generator or graphics gener-
`ators as appropriate.
`:
`At the beginning of every row of
`characters all the latches are set to
`white, alphanumeric, steady according
`to the teletext convention. The output
`
`Fig. 5. Display unit at Viewdata
`terminal. The number and bar on
`certain connecting lines indicate that
`the line is éarrying parallel information
`on that numberof wires. Some
`commercial Viewdatatv receivers may
`have clock frequencies other than 8
`MHz.
`
`of the decoderis applied the output unit
`. which provides R, G, B signals to the
`gunsof the cathode-ray tube.
`Non-contro! codes are applied to the
`alphanumeric character generator
`which generates the required character
`> pattern. This generator also receives a
`.4-bit line address from the syne genera-
`tor, which indicates which line out of
`the ten lines required for character
`display has been selected at any one
`time. Whena line of dotsis fed out from
`the character generatorit is entered in
`5-bit parallel form in a.5-stage shift
`register and clocked out in the next lys
`period at the 8MHz rate, under the
`control of the 8MHzclock.
`Ifa graphics control character is
`displayed, a latch is set in the display
`control codes decoder to indicate that
`all subsequent characters are graphics.
`- Theinhibition is lifted, however, in the
`case of the “blast-through” characters ©
`in columns4 and 5 of Fig. 61in the April
`issue.
`Generation of graphic symbolsis car-
`ried out under the control of vertical
`and horizontal bright-up waveforms,
`generated in the graphics generator.
`The horizonal bright-up waveform
`picks upleft, right or both coloumnsof
`the graphics symbol while the vertical
`bright-up waveform picks up one or
`more of the top, middle or bottom pair
`of squares in the graphics symbols. The
`7-bit graphic character is decoded with
`the aid of these two waveforms. and
`control signals applied to the_ output
`unit.
`
`Thedisplay of the Viewdata cursoris
`initiated by the address selector, which
`notes the coincidence of input and out-
`-put memory addresses and enables an
`exclusive-OR gate in the output unit.
`This causes normal display of charact-
`ers when the cursorisoff, but inverted
`display (i.e. black on white) when the
`cursor is on. Thus characters on display
`may be read through the cursor.
`Character rounding is provided in the
`character rounding unit when this feat-
`ure is required, i.e. mostly with large
`screen displays. Character rounding is
`initiated by the odd/even signal gene-
`rated together with the line interlace
`pulse in the ‘sync generator unit. A
`second alphanumeric character genera-
`tor unit similar to unit (3) may be
`required, both units operating simulta-
`neously out of step by oneline of the 7
`X 5 character matrix. The two outputs,
`one delayed with respect to the other,
`are compared in the character rounding
`unit and additional dot pulses generated
`half way in the 8MHz dot interval and
`transmitted to the output unit to give
`thé required result.
`The use of character roundingis not.
`necessary in the case of the small-size
`Viewdataphone display for ‘use in the
`office, and this results in a useful sim-
`plification.
`
`(To be continued)
`
`A limited number of commercial tele--
`vision sets containing Viewdata/tele-
`text decoders are now being manufac-
`tured for marketing trials of Viewdata
`due to start in. March 1978. In a later
`issue we hope to publish an article
`outlining the main features of a typical
`commercial set of this kind.
`
`Page 59
`
`PMC Exhibit 2069
`PMC Exhibit 2069
`Apple v. PMC
`Apple v. PMC
`IPR2016-00753
`IPR2016-00753
`Page 7
`Page 7
`
`ees
`
`Wireless World, May 1977
`
`EiIota
`
`Lt iarerolen)
`access
`memory
`
`II I|
`
`lortetoly
`
`Address
`selector
`
`Address
`
`fs
`
`yI|—
`
`Nella)
`
`