Patent Application: US-52843974-A

Abstract:
a novel high voltage power supply is disclosed which generates an unregulated output voltage from a dc input voltage . the magnitude of the unregulated output voltage may exceed the magnitude of the applied dc voltage . this output voltage appears across a capacitor which is in series with an inductor and a switch . the dc voltage is applied across the inductor and switch , and the switch is periodically closed by an oscillator . while the switch is closed , the voltage across the capacitor increases from energy supplied by the dc voltage . when the switch is open , the voltage on the capacitor is further increased by energy that was stored in the inductor while the switch was closed . a sensing circuit controls the opening and closing of the switch . the high voltage power supply is especially adaptable for use with a display of the gas discharge or plasma type .

Description:
it will be appreciated that the present invention can take many forms and embodiments . the true essence and spirit of this invention are defined in the appended claims , and it is not intended that the embodiment of the invention presented herein should limit the scope thereof . referring now to fig1 the external configuration of the portable data entry apparatus of this invention is shown . this apparatus is comprised of a keyboard input - display unit 90 , a housing 91 in which a tape deck mechanism and a majority of the electronics embodying this invention are located and into which a magnetic cassette tape cartride 94 may be inserted , and the cable 92 which connects housing 91 and keyboard - display unit 90 . a specific function , e . g ., the entry of data , to be performed by the portable data entry apparatus is selected by the operator . this is accomplished by utilization of the keyboard input - display unit 90 . the electronics which reside in housing 91 detect the function to be performed , and , in the case of data entry , generate proper electrical signals to cause the data to be written on the tape in the tape cartridge 94 . also the electronics position the tape such that it is ready to accept new data . referring now to fig2 there is shown a block diagram of the portable data entry apparatus of this invention . it is comprised of microcomputer set 100 , clock 102 , port selector 103 , input port 104 , output port 105 , deck motion control 106 , read - write circuitry 107 , bit cell timer 108 , display 109 , high voltage power supply 110 , keyboard switch and interrogation assembly 111 , alarm 112 , delay 113 , modem 114 , power supply 115 , power switching 116 , alarm clock 117 , emitter detector 118 , segment selector 119 , digit selector 120 , and modem 121 . it will be appreciated that the block diagram is presented to give a general understanding of interrelation of the above interrelated elements . it should also be appreciated that the detailed interconnection of the various devices is not given at this point for ease of presentation of the block diagram . the detailed interconnection of these devices will be set forth later in the specification . the operation of the apparatus of this invention begins , with reference to fig2 by assuming that no previous data have been recorded on tape and that the operator is just beginning to use the apparatus . tape cartridge 94 , is , therefore , inserted in the housing 91 , and the power switch on . keyboard input - display unit 90 is engaged in the &# 34 ; on &# 34 ; position . this switch is schematically shown in fig1 , and its being engaged &# 34 ; on &# 34 ; causes power supply 115 to be activated . since the source of power for the portable data entry apparatus of this invention is batteries , it is desirable to minimize the consumption of battery power . power switching unit 116 ( fig2 ) accomplishes this by supplying power to certain component parts only when power to those parts is required for proper operation . for example , power is supplied to the modem 121 only when the operator puts the unit in the &# 34 ; send &# 34 ; mode as described below , and power is supplied to the tape deck only when the operator puts the unit in either the send or record modes . furthermore , battery power is conserved when in other modes by switching the power to certain component parts of the apparatus at periodic intervals . the length of time that power is available to these components is referred to as the &# 34 ; awake &# 34 ; time , and the length of time that it is not available is referred to as the &# 34 ; asleep &# 34 ; time . in the preferred embodiment of this invention the maximum &# 34 ; awake &# 34 ; time is approximately 2 . 5 milliseconds , and the &# 34 ; asleep &# 34 ; time is approximately 7 . 5 milliseconds . power supply 115 , when activated , supplies power directly to the microcomputer set 100 , and the microcomputer set 100 begins to execute a series of predetermined instructions , as later illustrated . since at this point in the operation only the power switch has been turned on , the microcomputer set 100 is interrogating the keyboard switch ( fig1 ) and interrogation circuitry 111 via the segment selector circuitry 119 to determine if a mode has been selected by the operator . since no previous data has been recorded on tape and the operator was just beginning to utilize the apparatus , assume now that the operator desires the enter the record mode . to enter the record mode for a new tape the operator must press first the mode key ( fig1 ) and then must depress the clear key ( fig1 ) for approximately 5 seconds . the microcomputer set 100 first detects that the mode key had been depressed and then that the clear key had been depressed for the required 5 seconds . after 5 seconds the microcomputer set generates commands via the output port 105 ( fig2 ) to the deck motion control 124 to cause the tape of the cartridge 93 to be rewound . after the tape has been rewound , the deck motor mechanism is enabled by deck motion control 124 to start the tape moving in the forward direction until the beginning of the tape is found . the beginning of tape is found by utilizing emitter detector 118 . the operator is now ready to begin entry of data . data may be entered by depressing the appropriate keys of the keyboard input - display unit 90 ( fig1 ) which are shown schematically in the keyboard switch and interrogation circuitry 111 of fig1 . suppose , for example , that the data &# 34 ; 12345 &# 34 ; were desired to be written onto tape . the operator would depress the &# 34 ; 1 &# 34 ; switch , followed by the &# 34 ; 2 &# 34 ; switch , etc . until the five switches have been depressed . the data are then displayed in the display unit 109 . if the operator had attempted to enter data into the data entry apparatus prior to entering the record mode , it would not have been accepted since the apparatus is in a no mode or idle status . the microcomputer set 100 at this time generates signals to the alarm circuitry 112 , and the alarm circuitry 112 detects these signals and drives a speaker for a specified period of time . the operator is , therefore , given an audible indication that the data apparatus is not in the proper mode to accept data entry . the above described alarm is present anytime that the portable data entry apparatus is in a no mode or idle status . in a manner to be later set forth in detail , when the portable data entry apparatus was placed in the record mode , the microcomputer set 100 started scanning the keyboard switch and interrogation circuitry 111 during the &# 34 ; awake &# 34 ; time to determine if a key has been depressed . as each key in the above example was depressed , it would be detected by the microcomputer set 100 during this scan and the information corresponding to that key would be detected and would be temporarily stored in the microcomputer set 100 . this stored information is then outputted to the display 109 via the segment selector 119 and the digit selector 120 during the &# 34 ; awake &# 34 ; time of power switching unit 116 , thereby giving the operator a visual indication of the entered data . in the preferred embodiment of this invention up to 12 digits may be displayed for any one entry . a primary use of the portable data entry apparatus of this invention is to enable merchandisers , e . g ., supermarket chains , to employ it for ordering information . each type of goods that is to be ordered will have a reference designation symbol , and it is common for this reference designator to be five digits in length . the operator would enter the reference designator of the product to be ordered . following this entry , he would enter the number of cases of that product to be ordered . for example , if the reference designator was &# 34 ; 12345 &# 34 ; and six cases were desired to be ordered , the operator &# 39 ; s data input would be &# 34 ; 1234506 +.&# 34 ; conversely , if in the above example only five cases needed to be ordered instead of six , the operator could correct this mistake on his next entry by entering &# 34 ; 1234501 -.&# 34 ; when the operator of the apparatus depresses either the plus or the minus key of the keyboard 90 , the microcomputer set 100 detects that fact and begins to prepare the stored information to be written onto the tape . it transmits this information in serial fashion via the output ports 105 to the read - write circuitry 107 which writes the information on the tape . the tape would then contain digitized coded signals corresponding to the data entry . also during this write time the microcomputer set 100 has generated commands to the deck motion control 106 via the output ports 105 so that the tape may be properly positioned to accept the data . when the information is being written onto tape power switching unit 116 supplies power to the deck motion control 106 and the read - write circuitry 107 . at this point it is appropriate to point out that the portable data entry apparatus of this invention has several optional features . these include case total , auto header , and check digit verification . check digit verification and case total are features which may be manually disabled , and auto header , if selected , becomes a permanent feature of the portable data entry apparatus . if the auto header feature is selected , a command will be generated by microcomputer set 100 to write a reference designator and a number designator as the first entry on tape . this occurs when the beginning of the tape is found by the emitter detector 118 as described above . in the preferred embodiment of this invention , the auto header reference designator is &# 34 ; ace0 ,&# 34 ; and the number designator is comprised of four numbers , e . g ., &# 34 ; 1234 .&# 34 ; the reference designator is permanently stored in microcomputer set 100 and the number designator ( corresponding to unit serial number ) is diode programmed ( 944a -- fig1 ) by inserting diodes corresponding to the binary coded decimal representation of the serial number . the reference designator and the number designator are always written onto the tape as the first entry if the option is installed . the case total option is selected by engaging the case total switch of keyboard input - display unit 90 into the &# 34 ; on &# 34 ; position . this switch is shown schematically in fig1 . the microcomputer set 100 detects that this option has been selected and for all the data entries keeps a running total of the number of cases of merchandise that have been ordered . this information is usable to the operator for freight and shipping information , because from case total he can estimate how many trucks are required to transport the total order to his location . the case total switch must be engaged in the &# 34 ; on &# 34 ; position during the entire time the data entry is being made in order to have an accurate case total . check digit verification is enabled by engaging the check digit verification switch on the keyboard input - display unit 90 . this switch is shown schematically in fig1 . when engaged , the microcomputer set 100 manipulates entered data by either modulus 10 ( double - add - double ) or modulus 11 ( ibm standard ) check digit schemes , which are known to those skilled in the art . the data entry must be 5 , 6 , 7 , or 8 digits for check digit verification to operate properly . another feature of the microcomputer set 100 is that it is capable of storing the three data entries previous to the data entry in progress . when the operator is in the record mode , the last entry on tape may be reviewed by depressing the scan key once , the second to last entry may be reviewed by depressing the scan key a second time , and the third from last entry may be displayed by depressing the scan key a third time . a fourth depression of the scan returns the operator to his entry in process , and if he had not selected an entry , the display entry will be blank . when the operator depresses the &# 34 ; plus &# 34 ; or &# 34 ; minus &# 34 ; key for the present entry , the data entry that was previously third entry back is no longer stored in the microcomputer set 100 . another feature of the portable data entry apparatus of this invention is the end - of - data mark which is written onto the tape whenever the operator exits the record mode . the microcomputer set 100 , upon detection of a mode change , automatically generates the sequence of bit signals to the read - write circuitry 107 via the output port 105 . in the preferred embodiment of this invention , this entry would be displayed as &# 34 ; end .&# 34 ; having entered data on the tape , the operator may now desire to enter the read mode . this may be accomplished by depressing the mode key ( fig1 ) followed by the read key ( fig1 ). when entering the read mode from the record mode , the display will show &# 34 ; end .&# 34 ; this is because the next entry on tape is the end of data mark as discussed above . when &# 34 ; end &# 34 ; is displayed , the portable data entry apparatus reverts to a no mode or idle status . at this time the microcomputer set 100 will generate a signal to the alarm circuitry 112 via the output ports 100 . this signal will be used by the alarm circuitry 112 to drive a speaker , thereby informing the operator that a mode request needs to be made . an alternative method of entering the read mode is to depress the mode key ( fig1 ) followed by the back key ( fig1 ). if the &# 34 ; mode &# 34 ; and the &# 34 ; back &# 34 ; keys are depressed when in the record mode , the portable data entry apparatus will back up and display the 10th entry back . this operation can be executed at any point on the tape . the apparatus displays the 10th entry back , and then automatically enters the read mode . yet another method of entering the read mode is to depress the mode key followed by the rwd key ( fig1 ). the microcomputer set 100 ( fig2 ) detects the depression of the mode and rwd keys and generates signals to the deck motion control 106 which cause the tape to be rewound . the beginning of tape is then found with the emitter detector 118 , and data may be read from the tape . after the read mode has been entered the operator has two methods for scanning or reviewing the data . he can &# 34 ; scan &# 34 ; his data by successively displaying each entry , or he can &# 34 ; search &# 34 ; for a particular entry or series of entries on tape . if the operator desires to scan the data , he does so by depressing the scan key when in the read mode . the entry at a given tape position is then displayed until the scan key is again depressed , at which time the next entry is displayed . this process can be repeated until the end of data is reached at which time &# 34 ; end &# 34 ; is displayed . if , on the other hand , the operator desires to search for a particular entry or series of entries he may initiate a search request . this is accomplished by depressing a data key when in the read mode . the microcomputer set 100 detects the depression automatically as an intention to do a search operation . the operator would then enter a mask into the display . the mask is the reference designator of the type of entry that he desires to display . for example , if he desired to know the number of cases of goods of type &# 34 ; 12345 &# 34 ; that had been ordered , he would enter the mask &# 34 ; 12345 .&# 34 ; the search feature is enabled by then depressing the &# 34 ; scan &# 34 ; key ( fig1 ) after the entry of the mask . read - write circuitry 107 then begins to read the information that is recorded on tape in a forward direction from the point on the tape where the search is initiated . the information that is read is presented to microcomputer set 100 via the bit cell timer 108 and the input ports 104 . when a match is made , the portable data entry apparatus will terminate the search and display the complete entry from tape . a match is made when each character in the mask compares to each character of the reference designator in the entry for as many characters as were entered in the mask . if the scan key is depressed again after the first match was found , the search operation will continue with the previous mask , thereby locating all entries on the tape with that reference designator . to change the mask after a match , the operator must depress the &# 34 ; clear &# 34 ; key and then enter a new mask and depress the &# 34 ; scan &# 34 ; key again . if , however , he desires to review entries one at a time after a match , the operator depresses the &# 34 ; clear &# 34 ; key followed by the &# 34 ; scan &# 34 ; key . it will be recalled from the above description of the record mode that the entry into the record mode was only described for a tape which contained no data . in the case that an operator desires to enter data onto a tape on which there is previously recorded data and in the case of returning to the record mode after a search has been completed , the record mode is entered by depressing first the mode and then the record keys . the microcomputer set 100 in its keyboard scan detects that these two keys have been depressed and generates signals to the deck motion control 106 to start the tape moving in the forward direction until the end of data mark is found . it will be recalled that any time that the portable data entry apparatus exited the record mode the microcomputer set 100 generated signals to cause an end of data mark to be written onto the tape . during the time that the tape is moving in the forward direction , information is being read from the tape by read - write circuitry 107 , and this information is presented to microcomputer set 100 via the bit cell timer 108 and the input ports 104 . when that end of data mark is detected by the microcomputer set 100 , signals are generated to the deck motion control 106 to stop the forward motion of the tape . the operator would then be at the proper place on the tape to begin additional data entries . having completed the data entry onto tape and , if desired , having reviewed the entered data , the operator would now or at some convenient time desire to transmit the entered data to a central location where his order would be processed . in order to transmit the information , the operator must put the portable data entry apparatus into the &# 34 ; send &# 34 ; mode , and this is accomplished by depressing first the &# 34 ; mode &# 34 ; key and then the &# 34 ; send &# 34 ; key . the microcomputer set 100 detects that the send mode has been selected and enabled the power switching unit 116 to supply power to the modem 122 . when the distant receiving end is connected to the modem the microcomputer set 100 generates commands which cause the data to be read from the tape by the read - write circuitry 107 . this information is presented to the modem 122 , and modem 122 translates the digital information into audio tones suitable for transmission over telephone wires . when the end of data mark is found on the tape the transmission is complete and the microcomputer set 100 generates signals which cause the tape to be rewound and then moved to the beginning of tape position . the portable data entry system is then ready to retransmit the data if required , and the display 109 will display the symbol &# 34 ; poll ,&# 34 ; which indicates to the operator that the data has been transmitted . having now set forth the functional interrelationship of the component parts of an embodiment of this invention , it is now appropriate to describe details of the structure which accomplishes the above enumerated functions . interconnections between the various components will be indicated in the drawings . in the detailed description of the circuitry , the values of resistance and potentiometers are given in ohms , and , unless otherwise noted these values have a tolerance factor of ± 5 percent and a power rating of one - quarter watt . the symbols &# 34 ; k &# 34 ; and &# 34 ; m &# 34 ; are used for one thousand and one million , respectively . unless otherwise noted , values of capacitance less than 1000 pfd will have a tolerance factor of ± 10 %, values of capacitance greater than 1000 pfd will have a tolerance factor of + 80 %, - 20 % and the working dc voltage rating of the capacitor will be 20 volts . the identification of transistors and diodes is given in their eia - registration number wherever possible . transistors and diodes not having eia - registered numbers , and operational amplifiers are identified by a motorola semiconductor products , inc . designation known to persons skilled in the art . the circuitry of this invention also utilizes digital integrated circuits to perform certain functions . the integrated circuits utilized are from the series 54l / 74l , the series 54ls / 74ls , and the series 54c / 74c , and identification of components is made by utilizing these designators . these series and the individual integrated circuits are described in &# 34 ; the ttl book for design engineers ,&# 34 ; published by texas instruments , inc . ( 1973 ). referring now to fig3 there is shown a schematic diagram of power supply 115 which is utilized in the preferred embodiment of this invention . the circuitry is comprised of potentiometers 125 through 127 , resistors 192 and 128 through 160 , capacitors 193 and 161 through 172 , transistors 173 through 183 , diodes 194 and 181 through 185 , operational amplifiers 186 through 189 , voltage regulator 190 , and inductor 191 , all connected as shown . transistor 177 is mounted on heatsink 195 . the function of power supply 115 is to supply power to the apparatus , and it derives its source of power from high quality nickel cadmium batteries . as used in the claims , the term &# 34 ; battery &# 34 ; should be understood to include either a single cell or a plurality of cells , connected in either series or parallel , to achieve the desire volt - amp rating required for proper operation of the portable data entry apparatus . the positive and negative sides of the battery are connected to the points v bat + and v bat - respectively . signal powsw becomes active when the power is turned &# 34 ; on &# 34 ; and causes voltage regulator 190 to be turned on . one of the outputs of the voltage regulator 190 is a signal designated as gnd . this signal is ground for the system , and when present , provides a flow path for current from v ccs and v dds to the respective components of the portable data entry apparatus . since batteries provide the source of power for the apparatus of this invention , it is desirable for the operator of this apparatus to know when the battery power is becoming low . this can be accomplished by the circuitry of power supply 115 by adjusting potentiometer 125 until the voltage at the positive input to operational amplifier 118 is equal to 2 . 4 volts with a battery potential of 17 volts . when the battery potential difference is less than 17 volts ( i . e ., through use has decreased to 17 volts ) the outputs of operational amplifier 188 will become active , thereby turning off transistor 180 . the signal lowbatt will then be active and inform the microcomputer set 100 ( fig5 ) of the low battery condition . due to the programming of the microcomputer as hereinafter set forth , when the lowbatt signal is received by the microcomputer , it proceeds to inform the operator of the low battery condition by generating appropriate signals to the digit selector 120 and to the segment selector 119 . these in turn activate the display 109 with a suitable pattern , e . g ., &# 34 ; lo .&# 34 ; the microcomputer set 100 also commands an end of data mark to be written on the tape to insure proper termination of the data record and generates signals to the deck motion control 106 to cause the tape to be rewound approximately 16 entries . when the potential difference across the batteries is less than 155 volts the output of operational amplifier 187 becomes active , thereby causing an electronic shut down of the unit by electronically disconnecting the batteries by removing substantially all the load from the batteries . this electronic shut down protects the batteries and prevents cell reversal . cell reversal requires replacement of the batteries , since they can no longer be recharged . the electronic shut down feature of the apparatus of this invention protects , therefore , the user &# 39 ; s investment in the batteries . in the preferred embodiment of this invention the values of types of the various components of fig3 are : potentiometer 125 has a maximum resistance of 10k , potentiometer 126 has a maximum resistance of 6k , and potentiometer 127 has a maximum resistance of 4k . the values and types of the other components utilized in fig3 are : referring now to fig4 there is shown the detailed schematic diagram of the power switching unit 116 which is utilized in the preferred embodiment of this invention . it is comprised of resistors 200 through 218 , inverter elements 219 through 224 , transistors 225 through 232 , and diodes 233 through 236 , and the devices are connected as shown . since the source of power for the portable data entry apparatus of this invention is batteries , it is desirable to prolong the length of time that useful battery power is available . power switching unit 116 accomplishes this by supplying power to certain component parts only when power to those parts is required for proper operation . for example , power is supplied to the modem 121 only when the unit is in the send mode and the tape is moving , and power is supplied to the tape deck only when the tape is to be moved . furthermore , battery power is conserved in the portable data entry apparatus by switching the power ( v cca and v dda ) to certain component parts of the apparatus at periodic intervals . the length of time that v cca and v dda are active is referred to as the &# 34 ; awake &# 34 ; time , and the length of time that v cca and v dda are inactive is referred to as the &# 34 ; asleep &# 34 ; time . in the preferred embodiment of this invention the maximum &# 34 ; awake &# 34 ; time is approximately 2 . 5 milliseconds , and the &# 34 ; asleep &# 34 ; time is approximately 7 . 5 milliseconds . in the preferred embodiment of the portable data entry apparatus of this invention , the values and types of the components utilized in the power switching unit 116 are : referring now to fig5 there is shown a portion of the microcomputer set 100 that is utilized in the preferred embodiment of this invention . it is comprised of a central processing unit ( cpu ) 300 , a random access memory ( ram ) 301 , a standard memory interface set comprised of devices 302 and 305 , read - only - memories ( rom ) 303 and 304 , decoder 306 , diode 307 and 308 , resistors 309 , 310 , and 311 , diodes 312 , inverter element 313 , capacitors 314 through 316 , and transistors 317 and 318 , and the devices are connected as shown . central processing unit 300 , ram 301 , the standard memory interface set comprised of devices 302 and 303 , and rom &# 39 ; s 303 and 304 comprise a mcs - 4 microcomputer set which is vended by intel corp . of santa clara , california . its operation is described in their users manual of february 1974 . for ease of presentation only two rom &# 39 ; s 303 and 304 are shown in fig5 but in the preferred embodiment of this invention , seven rom &# 39 ; s are utilized in the microcomputer set 100 . the rom &# 39 ; s not shown are connected in the same fashion as the two rom &# 39 ; s that are shown . as discussed in the intel corp . users manual for the microcomputer set , cpu 300 is preferably an intel 4004 , ram 301 is preferably an intel 4002 - 1 , device 302 is preferably an intel 4008 , device 305 is preferably an intel 4009 , and the rom &# 39 ; s are preferably intel 1702a &# 39 ; s . decoder 306 is a 74l42 , and it is utilized to decode the binary values assumed by the control lines which are outputs of device 302 . the output corresponding to the decoded input is used to select a particular rom which is to be accessed . therefore , since seven rom &# 39 ; s are used in the preferred embodiment of this invention , seven output lines ( binary values 0 - 6 ) of decoder 306 are utilized to select the appropriate rom . resistors 309 are pullup resistors for the outputs of the rom &# 39 ; s , and in the preferred embodiment of this invention are 20k in value . the contents of each address of each rom are programmed to contain a particular bit configuration . when a rom is addressed by the cpu 300 , this bit configuration is available at the output of the rom for use by the cpu 300 . the particular bit configuration is , of course , dependent upon the function that is to be performed . the preferred programming of the contents of each address of each rom is given below . each rom contains 256 addresses , and the contents of each address is given in the decimal equivalent of its binary value . those skilled in the art will realize that in order to program the rom , a conversion from decimal to binary must be accomplished . rom number 1__________________________________________________________________________addresses 0 to 127addressvalue address value address value address value__________________________________________________________________________0 216 32 161 64 231 96 371 81 33 46 65 216 97 202 72 34 48 66 228 98 1123 84 35 47 67 82 99 2424 23 36 228 68 189 100 285 81 37 220 69 26 101 1066 77 38 81 70 73 102 817 32 39 72 71 82 103 728 48 40 85 72 163 104 649 33 41 209 73 82 105 10410 236 42 68 74 219 106 8211 177 43 229 75 46 107 3612 85 44 65 76 13 108 2013 23 45 49 77 47 109 3714 33 46 67 78 224 110 6615 48 47 223 79 126 111 7416 49 48 17 80 77 112 23717 28 49 60 81 81 113 17718 245 50 27 82 252 114 20819 82 51 142 83 20 115 22920 36 52 140 84 89 116 6421 20 53 44 85 81 117 3022 37 54 213 86 64 118 21623 18 55 46 87 64 119 22824 30 56 138 88 245 120 8425 68 57 241 89 218 121 23526 231 58 97 90 143 122 20927 84 59 118 91 26 123 22628 235 60 28 92 81 124 8229 177 61 245 93 85 125 16330 85 62 230 94 209 126 8231 173 63 209 95 64 127 235__________________________________________________________________________ rom number 1__________________________________________________________________________addresses 128 to 255addressvalue address value address value address value__________________________________________________________________________128 85 160 227 192 168 224 82129 156 161 46 193 246 225 137130 46 162 255 194 246 226 64131 93 163 47 195 18 227 37132 82 164 227 196 209 228 113133 196 165 82 197 33 229 157134 26 166 219 198 233 230 85135 209 167 81 199 96 231 178136 70 168 252 200 33 232 64137 130 169 28 201 232 233 37138 69 170 85 202 28 234 0139 37 171 218 203 167 235 82140 65 172 143 204 176 236 36141 17 173 18 205 241 237 18142 28 174 40 206 97 238 30143 245 175 43 207 127 239 68144 230 176 209 208 197 240 60145 214 177 231 209 81 241 20146 228 178 32 210 64 242 235147 85 179 12 211 64 243 213148 178 180 33 212 0 244 229149 82 181 208 213 28 245 46150 189 182 224 214 245 246 44151 26 183 97 215 82 247 82152 157 184 33 216 36 248 196153 84 185 177 217 20 249 26154 235 186 233 218 37 250 253155 82 187 20 219 18 251 65156 163 188 209 220 30 252 7157 46 189 244 221 242 253 44158 128 190 242 222 28 254 64159 47 191 191 223 228 255 85__________________________________________________________________________ rom number 2__________________________________________________________________________addresses 0 to 127addressvalue address value address value address value__________________________________________________________________________0 211 32 37 64 212 96 1751 26 33 233 65 83 97 2452 5 34 186 66 218 98 2453 84 35 185 67 82 99 1794 235 36 184 68 235 100 2475 82 37 183 69 83 101 1786 203 38 182 70 218 102 1717 46 39 35 71 216 103 208 86 40 224 72 46 104 1659 210 41 164 73 0 105 24610 85 42 248 74 47 106 9911 3 43 180 75 225 107 2612 83 44 99 76 192 108 10513 245 45 123 77 32 109 18714 218 46 32 78 11 110 3315 64 47 64 79 181 111 24116 33 48 37 80 240 112 23717 208 49 217 81 183 113 14718 228 50 228 82 46 114 2819 85 51 44 83 255 115 12120 173 52 50 84 44 116 23621 179 53 46 85 255 117 14622 217 54 16 86 111 118 24623 224 55 212 87 47 119 1824 36 56 85 88 227 120 13325 63 57 3 89 45 121 24126 38 58 84 90 227 122 23927 238 59 235 91 33 123 14728 40 60 82 92 234 124 2829 238 61 163 93 20 125 15230 42 62 64 94 165 126 23831 231 63 209 95 187 127 146__________________________________________________________________________ rom number 2__________________________________________________________________________addresses 128 to 255addressvalue address value address value address value__________________________________________________________________________128 246 160 241 192 235 224 203129 26 161 20 193 81 225 214130 152 162 102 194 233 226 184131 238 163 67 195 117 227 250132 16 164 245 196 220 228 125133 236 165 113 197 35 229 208134 184 166 86 198 233 230 0135 219 167 33 199 36 231 0136 136 168 164 200 203 232 0137 18 169 228 201 115 233 0138 154 170 165 202 204 234 0139 185 171 229 203 171 235 0140 209 172 166 204 246 236 0141 186 173 230 205 187 237 211142 43 174 167 206 26 238 190143 236 175 231 207 246 239 241144 20 176 192 208 81 240 216145 150 177 36 209 232 241 136146 208 178 15 210 82 242 184147 228 179 40 211 194 243 47148 105 180 224 212 26 244 226149 105 181 37 213 218 245 192150 185 182 209 214 223 246 219151 16 183 226 215 182 247 190152 162 184 82 216 65 248 126153 16 185 219 217 193 249 248154 168 186 179 218 65 250 65155 180 187 244 219 216 251 210156 182 188 189 220 0 252 83157 163 189 83 221 0 253 217158 181 190 217 222 0 254 82159 183 191 82 223 116 255 214__________________________________________________________________________ rom number 3__________________________________________________________________________addresses 0 to 127addressvalue address value address value address value__________________________________________________________________________0 46 32 25 64 18 96 1931 64 33 25 65 97 97 2462 47 34 68 66 246 98 1613 216 35 229 67 114 99 204 226 36 46 68 78 100 1135 36 37 8 69 46 101 186 15 38 47 70 16 102 1167 40 39 236 71 47 103 2488 1 40 241 72 223 104 1149 42 41 143 73 229 105 10810 59 42 26 74 83 106 2811 83 43 49 75 245 107 6912 32 44 228 76 64 108 24413 20 45 176 77 37 109 17714 11 46 237 78 18 110 24015 139 47 66 79 81 111 22916 20 48 56 80 207 112 19317 32 49 238 81 209 113 24818 168 50 143 82 129 114 22819 246 51 26 83 18 115 19220 246 52 115 84 74 116 24821 18 53 230 85 242 117 3222 25 54 176 86 242 118 18723 83 55 239 87 20 119 2824 59 56 248 88 74 120 7425 101 57 177 89 217 121 8326 221 58 110 90 129 122 24527 181 59 47 91 26 123 11228 37 60 237 92 74 124 12629 224 61 178 93 242 125 19330 69 62 160 94 177 126 4631 23 63 246 95 250 127 15__________________________________________________________________________ rom number 3__________________________________________________________________________addresses 128 to 255addressvalue address value address value address value__________________________________________________________________________128 82 160 161 192 82 224 245129 237 161 224 193 235 225 26130 46 162 192 194 46 226 222131 14 163 82 195 47 227 208132 82 164 219 196 47 228 226133 196 165 83 197 234 229 218134 18 166 217 198 246 230 81135 121 167 85 199 127 231 72136 192 168 23 200 198 232 212137 85 169 28 201 191 233 83138 166 170 183 202 192 234 218139 35 171 82 203 208 235 46140 233 172 194 204 83 236 47141 99 173 18 205 218 237 210142 28 174 167 206 212 238 190143 149 175 82 207 82 239 47144 242 176 194 208 214 240 226145 224 177 18 209 234 241 190146 240 178 185 210 245 242 212147 35 179 85 211 26 243 190148 224 180 23 212 209 244 47149 35 181 20 213 208 245 190150 211 182 175 214 46 246 216151 235 183 64 215 32 247 226152 18 184 245 216 47 248 226153 69 185 46 217 226 249 0154 233 186 43 218 192 250 0155 179 187 66 219 216 251 25156 233 188 237 220 82 252 251157 242 189 218 221 214 253 127158 224 190 81 222 234 254 237159 35 191 72 223 245 255 192__________________________________________________________________________ rom number 4__________________________________________________________________________addresses 0 to 127addressvalue address value address value address value__________________________________________________________________________0 176 32 169 64 71 96 2461 49 33 20 65 100 97 1892 50 34 89 66 212 98 2403 179 35 43 67 148 99 1824 52 36 234 68 28 100 1925 181 37 20 69 71 101 476 182 38 82 70 180 102 2347 55 39 123 71 37 103 2458 56 40 91 72 173 104 269 185 41 250 73 248 105 13810 186 42 135 74 224 106 16011 59 43 246 75 223 107 24612 188 44 125 76 185 108 17613 61 45 50 77 38 109 16114 62 46 18 78 0 110 24615 174 47 50 79 42 111 17716 240 48 127 80 59 112 24717 225 49 75 81 192 113 22618 226 50 168 82 17 114 12419 243 51 246 83 89 115 13820 228 52 246 84 118 116 23921 245 53 18 85 100 117 18822 246 54 75 86 209 118 23823 231 55 245 87 121 119 17624 232 56 245 88 76 120 8325 249 57 26 89 241 121 3226 250 58 63 90 197 122 4727 235 59 104 91 246 123 23428 252 60 104 92 26 124 24529 237 61 208 93 95 125 2630 238 62 189 94 103 126 12031 255 63 117 95 173 127 247__________________________________________________________________________ rom number 4__________________________________________________________________________addresses 128 to 255addressvalue address value address value address value__________________________________________________________________________128 226 160 176 192 197 224 228129 168 161 85 193 242 225 44130 246 162 156 194 242 226 69131 26 163 85 195 28 227 85132 139 164 166 196 198 228 211133 241 165 160 197 184 229 26134 245 166 20 198 233 230 243135 184 167 202 199 177 231 83136 32 168 64 200 48 232 245137 255 169 241 201 192 233 82138 192 170 241 202 46 234 219139 83 171 115 203 110 235 83140 32 172 179 204 82 236 217141 163 173 98 205 196 237 46142 241 174 212 206 46 238 43143 149 175 146 207 84 239 82144 28 176 28 208 44 240 237145 170 177 179 209 102 241 81146 241 178 178 210 210 242 64147 162 179 83 211 18 243 64148 148 180 32 212 215 244 37149 28 181 47 213 64 245 216150 170 182 234 214 33 246 83151 143 183 245 215 65 247 252152 26 184 26 216 55 248 46153 136 185 179 217 214 249 41154 209 186 240 218 46 250 82155 226 187 226 219 48 251 237156 46 188 35 220 47 252 46157 12 189 210 221 226 253 16158 82 190 222 192 254 47159 237 191 18 223 211 255 226__________________________________________________________________________ rom number 5__________________________________________________________________________addresses 0 to 127addressvalue address value address value address value__________________________________________________________________________0 192 32 35 64 26 96 871 249 33 240 65 112 97 2172 164 34 232 66 175 98 813 176 35 20 67 246 99 724 153 36 59 68 26 100 2205 146 37 187 69 74 101 2266 131 38 208 70 85 102 1107 248 39 179 71 173 103 858 128 40 46 72 68 104 239 152 41 128 73 231 105 2810 136 42 185 74 46 106 23111 198 43 35 75 29 107 4712 143 44 233 76 82 108 23413 134 45 177 77 196 109 24614 191 46 56 78 176 110 1815 226 47 47 79 26 111 10316 146 48 227 80 87 112 21717 134 49 41 81 175 113 8118 171 50 227 82 245 114 7219 161 51 99 83 26 115 22220 140 52 111 84 97 116 22621 192 53 221 85 64 117 4622 199 54 177 86 37 118 823 34 55 113 87 85 119 8224 45 56 55 88 23 120 23725 35 57 123 89 28 121 4726 239 58 43 90 231 122 22027 176 59 192 91 46 123 22628 98 60 46 92 29 124 20929 35 61 110 93 82 125 8330 239 62 82 94 196 126 25231 178 63 196 95 26 127 219__________________________________________________________________________ rom number 5__________________________________________________________________________addresses 128 to 255addressvalue address value address value address value__________________________________________________________________________128 82 160 83 192 197 224 23129 230 161 101 193 242 225 20130 46 162 250 194 245 226 160131 14 163 43 195 245 227 67132 82 164 191 196 16 228 160133 237 165 154 197 242 229 84134 34 166 26 198 212 230 254135 0 167 172 199 180 231 83136 36 168 223 200 37 232 245137 0 169 191 201 180 233 64138 32 170 68 202 216 234 33139 255 171 198 203 226 235 82140 46 172 168 204 212 236 203141 111 173 246 205 18 237 212142 82 174 246 206 209 238 83143 196 175 18 207 105 239 252144 46 176 156 208 214 240 82145 16 177 219 209 43 241 189146 47 178 155 210 226 242 26147 26 179 20 211 38 243 240148 151 180 185 212 160 244 83149 216 181 83 213 83 245 252150 16 182 61 214 101 246 82151 219 183 68 215 83 247 185152 231 184 156 216 32 248 82153 243 185 241 217 20 249 189154 247 186 165 218 213 250 26155 230 187 147 219 17 251 237156 40 188 243 220 229 252 65157 16 189 164 221 83 253 71158 42 190 146 222 101 254 211159 59 191 26 223 85 255 44__________________________________________________________________________ rom number 6__________________________________________________________________________addresses 0 to 127addressvalue address value address value address value__________________________________________________________________________0 3 32 246 64 37 96 2421 46 33 26 65 82 97 2302 33 34 36 66 137 98 1313 180 35 206 67 210 99 184 209 36 192 68 129 100 975 85 37 32 69 20 101 856 174 38 0 70 75 102 1787 179 39 28 71 242 103 818 164 40 144 72 242 104 649 224 41 82 73 26 105 11810 244 42 36 74 63 106 14211 242 43 20 75 46 107 22612 180 44 63 76 79 108 8313 188 45 18 77 82 109 24514 189 46 144 78 196 110 8515 190 47 242 79 26 111 20916 191 48 20 80 83 112 8517 35 49 65 81 86 113 16618 224 50 46 82 76 114 17719 99 51 63 83 46 115 20920 116 52 47 84 77 116 23021 13 53 239 85 82 117 8422 192 54 248 86 196 118 25423 38 55 18 87 26 119 3424 80 56 58 88 91 120 1525 39 57 211 89 85 121 4426 234 58 231 90 250 122 127 245 59 113 91 81 123 22328 18 60 63 92 177 124 9929 31 61 85 93 85 125 3530 207 62 178 94 166 126 22431 246 63 64 95 238 127 125__________________________________________________________________________ rom number 6__________________________________________________________________________addresses 128 to 255addressvalue address value address value address value__________________________________________________________________________128 124 160 224 192 43 224 17129 81 161 126 193 227 225 248130 177 162 159 194 40 226 250131 221 163 127 195 4 227 234132 179 164 159 196 41 228 20133 82 165 192 197 240 229 224134 185 166 34 198 187 230 127135 35 167 60 199 234 231 224136 224 168 35 200 245 232 46137 226 169 238 201 245 233 11138 85 170 231 202 241 234 234139 209 171 178 203 246 235 28140 64 172 192 204 241 236 232141 32 173 208 205 246 237 126142 64 174 34 206 137 238 234143 0 175 32 207 185 239 127144 85 176 35 208 192 240 234145 173 177 231 209 44 241 125146 161 178 85 210 79 242 218147 248 179 166 211 82 243 46148 20 180 35 212 219 244 63149 61 181 224 213 82 245 82150 213 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48 60 80 85 112 6917 75 49 241 81 186 113 10518 107 50 46 82 180 114 16919 188 51 153 83 169 115 24620 189 52 218 84 147 116 23321 120 53 156 85 18 117 2622 13 54 241 86 217 118 12123 211 55 251 87 131 119 24124 137 56 188 88 244 120 24525 147 57 249 89 189 121 25126 26 58 157 90 162 122 13927 75 59 189 91 184 123 25128 20 60 42 92 175 124 18729 39 61 15 93 245 125 7030 248 62 241 94 245 126 9931 20 63 220 95 208 127 192__________________________________________________________________________ rom number 7__________________________________________________________________________addresses 128 to 255addressvalue address value address value address value__________________________________________________________________________128 67 160 123 192 251 224 111129 245 161 146 193 18 225 192130 85 162 220 194 196 226 163131 178 163 224 195 242 227 20132 179 164 69 196 180 228 225133 217 165 91 197 241 229 240134 224 166 147 198 118 230 43135 38 167 18 199 190 231 233136 171 168 217 200 218 232 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, resistors 352 , 353 , 358 , 379 , 380 , and 384 , transistor 357 , inverter elements 360 , 361 , 365 , 373 , 374 , 381 , 382 and 385 , nand gates 364 and 367 through 370 , nand gates 369 and 370 , flip flops 362 , 363 , 366 , 371 , and 372 , mos driver 367 , and diode 383 , connected as shown . reference to the intel corp . user &# 39 ; s manual for the mcs - 4 microcomputer set reveals that the microcomputer has an instruction cycle time of 10 . 8 microseconds . during this instruction cycle two clocks must each have active states eight times . these clock pulses are provided by the clock circuitry shown in fig6 . in the preferred embodiment of this invention , crystal 354 has a frequency of 5 . 185 mhz . this frequency is counted down by the divide by seven counter comprised of flip - flops 362 , 363 , and 366 . the frequency of the outputs of nand gates 369 and 370 are , therefore , one - seventh of 5 . 185 mhz . the inverted outputs of these nand gates furnish the two clocks required by the microcomputer set 100 . the values and types of the various enumerated components should be : referring now to fig7 there is shown a detailed schematic diagram of the port selector 103 that is used in the portable data entry apparatus of this invention . the circuitry is comprised of decoders 390 and 391 , inverter elements 392 through 395 , nor gate 396 , and diode 397 and is connected as shown . as shown , the inputs to decoder 390 are the control signals c0 , c1 , and c2 from the microcomputer set 100 and the signal cpurst from the output port 105 . the binary value of these inputs is decoded by decoder 390 , and depending on the value of the inputs , one and only one of decoder 390 &# 39 ; s outputs will be active at any one time . the active output is used to select the appropriate output port to which the microcomputer set will output information via the input / output lines of device 305 ( fig5 ). the inputs to decoder 391 are the control signals c1 , c2 , c3 , and nin from the microcomputer set . the decoder 391 decodes the binary value of these inputs , and one of the outputs nin01 , nin23 , nin45 , or nin67 will be active depending upon the value of the input . the active output is used to select the input port from which data will be entered into device 305 via the input / output lines shown in fig5 . in the preferred embodiment of the invention , the type of each element in the port selector circuitry is : referring now to fig8 there is shown the input port circuitry which is utilized in the preferred embodiment of this invention . as shown it is comprised of data selectors 400 through 403 . the data selectors are preferably 81l23 &# 39 ; s which are manufactured by national semiconductor corporation . referring now to fig9 there is shown the output port circuitry 105 of fig2 that is utilized in the portable data entry apparatus of this invention . it is comprised of storage devices 448 through 451 , inverter elements 452 through 465 , nand gates 366 thrugh 368 , nor gates 369 through 371 , and resistor 372 and is connected as shown . the data inputs to the output port 105 are the bidirectional input / output lines from device 305 as shown in fig5 . one of the other input signals enotφ through enot4 from the port selector 103 , selects a storage element ( 448 , 449 , 450 , or 451 ) into which data on the input / output lines is to be loaded . the data present at the output of the device selected has the same logical value as the input . the types of the devices utilized in the preferred embodiment of this invention for implementation of the output port 105 are : referring now to fig1 , there is shown the read - write circuitry 107 of fig2 which is utilized in the preferred embodiment of this invention . the circuitry is comprised of nand gates 500 through 503 , transistors 504 through 508 , resistors 509 through 535 , capacitors 538 through 544 , operational amplifiers 546 and 547 , comparators 549 through 551 , and diodes 552 through 554 , all connected as shown . the function of the circuitry shown in fig1 is to write digitized information onto tape and to read digitized information from tape upon command . data is written onto tape when the command write is a logical one , and while data from the tape is always available at the output of read - write circuitry 107 , it is utilized only upon command from the microcomputer set 100 . in the preferred embodiment of this invention the values and types of the components utilized in fig1 are : referring now to fig1 , there is shown the schematic diagram of the deck motion control 106 which is utilized in the portable data entry apparatus of this invention . it is comprised of transistors 1100 through 1120 , operational amplifiers 1125 and 1126 , resistors 1131 through 1168 , capacitors 1170 through 1176 , diodes 1177 through 1178 and potentiometers 1179 and 1180 and is connected as shown . in the preferred embodiment of this invention the values and types of the components shown in fig1 are : referring now to fig1 , there is shown the schematic diagram of the alarm clock circuitry 117 of fig2 which is utilized in the preferred embodiment of this invention . it is comprised of inverter elements 600 and 607 , nand gates 608 through 610 , operational amplifiers 111 through 614 , resistors 615 through 633 , capacitors 634 through 641 , diodes 642 through 645 , and flip flop 646 , all connected as shown . alarm circuitry 117 receives inputs from microcomputer set 100 ( fig5 ), and generates the signal msleep which is utilized to switch between the &# 34 ; awake &# 34 ; and &# 34 ; asleep &# 34 ; times . in the preferred embodiment of this invention , the values and types of the components utilized are : referring now to fig1 , there is shown the alarm 112 which is utilized in the preferred embodiment of this invention . the signal nalm , from output port 105 , when active signifies an alarm condition . this signal turns on transistor 752 which triggers timer 753 . the output of timer 753 then drives speaker 754 for a time , and this speaker can be heard by the operator of the portable data entry apparatus . in the preferred embodiment of this invention the values and types of the components of the alarm circuitry are : it should be observed that while an ne555n is the preferred type of device for timer 753 , any compatible monostable multivibrator may be used in place of it . referring now to fig1 , there is shown bit cell timer 108 that is used in the preferred embodiment of this invention . it is comprised of flip flops 800 and 806 , counters 807 and 808 , decoders 809 and 810 , exclusive or gates 811 through 813 , nand gates 814 through 821 , nor gates 822 through 825 , and inverter gates 826 through 830 . the function of the bit cell timer is to determine the binary value of the information read from the magnetic tape . in the preferred embodiment of this invention the various types of devices utilized are : while the foregoing schematic diagram illustrates the preferred exemplification of the bit cell timer , it should be evident to those skilled in the art of logic design that the above described circuitry could be implemented using a wide variety of devices as substitutes for those enumerated above . any equivalents of the above enumerated circuitry should , therefore , be so construed . referring now to fig1 , there is shown a schematic diagram of the emitter detector 118 used in the portable data entry apparatus of this invention . the function of the emitter detector circuitry is to detect the presence of information upon the tape and to give an indication to the mirocomputer set 100 via the input port circuitry when the digit is detected . the emitter detector circuitry is comprised of timers 760 and 761 , transistors 762 - 764 , resistors 765 - 773 , capacitors 774 - 778 , and diodes 779 - 784 . the values and types of components utilized are : referring now to fig1 , there is shown the detailed schematic diagram of the delay 113 circuitry which is utilized in the portable data entry apparatus of this invention . it is comprised of timer 850 , transistors 815 through 854 , resistors 855 through 864 , potentiometer 865 , and capacitors 866 through 868 . in the preferred embodiment of this invention the values and types of the components utilized in the delay circuitry of this invention are : referring now to fig1 , there is shown the segment selector 119 that is utilized to select the appropriate segment or segments of the display 109 of fig2 to be displayed . the circuitry is comprised of nand gates 880 through 887 , inverting elements 888 through 894 , storage device 895 , transistors 896 through 902 , resistors 903 through 911 , resistor packages 912 and 913 , capacitors 914 through 920 , and diodes 922 and is connected as shown . during the period of time that inverter 894 is a logical one , nand gates 880 through 886 are enabled and a logical one present on any of the input lines nda0 - nda6 from the microcomputer set will cause the respective transistors 896 through 902 to be forward biased , and voltage v ccs will be present at the collector of any forward biased transistor . the collectors of transistors 896 through 902 are connected directly to the segment inputs of display 109 ( fig2 ). during the period of time that the pulse nldstb is active , signals ndaφ through nda3 are loaded into storage device 895 and appear at the outputs of storage device 895 . these outputs are decoded by both the digit selector 120 and the keyboard switch and interrogation assembly 121 . referring still to fig1 , the values and types of the components in the preferred embodiment of this invention are : referring now to fig1 , there is shown the digit selector 120 that is utilized in a preferred embodiment of the portable data entry apparatus of this invention . it is comprised of transistors 922 through 933 , decoder 934 , zener diode 935 , and resistor packages 936 and 937 and is connected as shown . the binary value of inputs s1 - s4 is decoded by decoder 934 . when decoding occurs , one and only one of the outputs of the decoder 934 will be active , thereby providing a forward bias for one and only one of the transistors 922 through 933 . the collectors of transistors 922 through 933 are connected to the digit inputs of display 109 ( fig2 ) and are used by display to select the proper digit which is to be displayed . in the preferred embodiment of this invention the values and types of the components utilized are : referring now to fig1 , there is shown the schematic representaion of the keyboard switch and interrogation assembly 121 that is utilized in a preferred embodiment of this invention . it is comprised of decoder 938 , inverting elements 939 through 942 , keyboard input switch unit 943 , and diodes 944 and is connected as shown . periodically inputs s1 - s4 from the segment selector will be activated . during the activation , binary values of 0 - 9 will be assumed by the four inputs . if one of the switches from keyboard input switch unit 943 have been depressed , that fact will be detected during the scan of binary values 0 to binary value 4 . outputs kero0 - kero3 will be active and this value will be read by the microcomputer set 100 through the input ports . the values and types of the components utilized in fig1 are : referring now to fig2 , there is shown the high voltage power supply 110 of fig2 which is utilized in the preferred embodiment of this invention . it is comprised of nand gates 950 through 953 , transistors 954 through 956 , resistors 957 through 964 , capacitors 965 through 967 , diodes 968 through 970 , inductor 971 , and capacitor 990 , all connected as shown . the function of this circuitry is to convert the battery voltage to a high voltage which can be utilized by a display of the gas discharge or plasma type such as display 109 of fig2 . power supply 110 functions , therefore , as a power converter . fig2 b is a simplified schematic diagram of the high voltage supply 110 which is shown in fig2 . it is basically a four terminal device which has four output contact points 2000 , 2001 , 2002 , and 2003 . a d - c voltage source is connected between the first contact point 2000 and the third contact point 2002 . inductor 971 is connected between second contact point 2001 and third contact point 2002 . capacitor 990 is connected between third contact point 2002 and fourth ( output ) contact point 2003 . a diode 2004 is connected between second contact point 2001 and fourth ( output ) point 2003 , with the cathode of diode 2004 connected to second contact point 2001 . a switch 2005 is connected between first contact point 2000 and second contact point 2001 . the switch 2005 of fig2 b is comprised of transistors 955 and 956 of fig2 . oscillator 2007 periodically closes switch 2005 , and it is comprised of nand gates 950 through 953 , resistors 958 through 961 , and capacitor 965 in fig2 . the sensing circuit 2006 is connected between fourth ( output ) contact point 2003 and oscillator 2007 . when d - c power is supplied to the portable data entry apparatus , oscillator 2007 periodically closes the switch 2005 (&# 34 ; on &# 34 ; time -- fig2 a ), and energy storage begins in inductor 971 . when switch 2005 is open (&# 34 ; off &# 34 ; time -- fig2 a ), current flows through the loop comprised of inductor 971 , capacitor 990 , and diode 2004 . diode 2004 operates , therefore , as a free wheeling or flyback diode . in the preferred embodiment of this invention , the duty cycle of the output of the oscillator 2007 , i . e ., the ratio of the &# 34 ; off &# 34 ; time to the &# 34 ; on &# 34 ; time shown in fig2 b , is equal to the ratio of the input voltage to the output voltage and is adjusted for efficiency . during the time switch 2005 is open , current is extracted from capacitor 990 by inductor 971 . the voltage at fourth ( output ) contact 2003 begins to increase negatively during openings of switch 2005 . if this voltage were not controlled , it would approach - 400 volts in value . sensing circuit 2006 operates as a control device for the volage at the fourth ( output ) contact point 2003 and prevents the voltage at that point from significantly going more negatively than - 170 volts . sensing circuit 2006 is comprised of resistors 957 and 964 , capacitor 966 , and transistor 954 in fig2 . when the signal at fourth ( output ) contact point 2003 reaches approximately - 170 volts , sensing circuit 2006 detects this voltage . it then inhibits oscillator 2007 from making further closures of switch 2005 until the output voltage hv - 170 becomes sufficiently more positive than - 170 volts . sensing circuit 2006 detects this rise in output voltage and enables oscillator 2007 . sensing circuit 2006 functions , therefore , to stop power conversions by the power supply 110 when the output voltage is significantly more negative than - 170 volts and to permit power conversion when the output voltage is significantly more positive than - 170 volts . the signal hv - 170 ( fig2 ) is presented to display unit 109 ( fig2 ), and it is the voltage that is used to activate display 109 when a character is to be displayed . the various types and values of the components in the preferred embodiment of fig2 are : referring now to fig2 , there is shown the circuitry that is utilized in conjunction with the high voltage power supply 110 in the preferred embodiment of this invention . it is comprised of transistors 975 through 977 , zener diodes 978 and 979 , capacitors 986 through 989 , and diode 991 , all connected as shown . the function of the power - saving circuitry of fig2 is to maintain appropriate voltages on display 109 for optimum display performance . the values and types of the components of the powersaving circuitry of fig2 are : referring now to fig2 , there is shown a portion of the modem circuitry that is utilized in the portable data entry apparatus of this invention . it is comprised of transistors 1000 through 1005 , diodes 1006 through 1009 , resistors 1010 through 1020 , and capacitor 1021 . this circuitry is utilized to interface with a data access arrangement . the values and types of the components utilized in this portion of the modem circuitry are : referring now to fig2 , there is shown another portion of the modem circuitry that it utilized in the preferred embodiment of this invention . it is comprised of flip flops 1025 through 1027 , timer 1028 nand gates 1029 and 1030 , inverter elements 1031 through 1035 , transistors 1036 through 1038 , voltage controlled oscillator 1039 , operational amplifiers 1040 and 1041 , potentiometers 1042 , 1060 , and 1061 , capacitors 1062 through 1070 , and resistors 1043 through 1059 , all of which are connected as shown in the figure . the values and types of the components utilized in this portion of the modem circuitry are :