Note: Descriptions are shown in the official language in which they were submitted.
5 7~ ~
l Hierarchical Computer System For
Generatin~ Selective Output Si~nals
In Response To Received Input Signals
This invention relates to a hierarchical computer
system for receiving înput signals from a plurality of
signal sources and for generating selective output sig-
nals in response to received input signals.
The invention further relates to a specific signal
detecting system in a hierarchical terminal based com-
puter system.
The use of a main computer, that is connectedthrough a transmission channel Gr a transmission line
to a smaller unit consisting of a more or less intelli-
gent terminal unit, is well known in the computer art.
This terminal unit may in turn control a plurality of
intelligent or non-intelligent smaller units, for in-
stance conventional input/output devices.
Such a hierarchical computer system is described
in IBM Technical Disclosure Bulletin, Vol. 19~ No. 3,
August 1976, pp 1063 and 1069, where a main computer
(not shown) is connected through a transmission channel
to a system control unit. The system control unit is
further connected to output devices as well as to a
number of micro control units, each of which controlling
a number of input/output devices.
One way of using a main computer with a terminal
unit for entrance checking is shown in the V.S. Patent
3,913,071. According to that system the terminal unit
receives signals from a signal source, assembles the
~W9-7g-0~1 -Z-
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1 information about these siynals and transfers them to a
main computer. The main computer processes the data and
thereafter signals the answer to the terminal unit, which
then activates an output device, preferably a door lock-
ing mechanism.
One problem in connection with a hierarchical com-
puter system, that receives input signals, processes
these signals and as a result o the processing issues
output signals to output devices, resides in the diffi-
culty of distributing optimally the processing functionsof the various computers of the system in such a way
that the system user's wishes are met wi'ch and that the
various computers are neither overloaded nor underloaded.
In accordance with what is stated above the present
invention relates to a hierarchical three-level computer
system with a host computer, a terminal computer and a
number of micro computers. Each microcomputer is con-
nected to a signal source for receiving and optimal de-
coding of input signals. The terminal computer rec¢ives
input information from the micro computers, compares
this information with stored table data, which may be
selectively altered from a keyboard, communicates selec-
tively with a host computer and generates output signals
to output devices.
The invention further relates to a computer system
with a terminal computer, which is equipped with a
plurality of screen storages for storing displayable
tables containing condition information enabling the in-
put information from signal sources to produce output
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1 signals to output devices.
The invention further concerns the use of an up and
down counting apparatus, which is loaded with a constant,
within the signal receiving micro computer for signal
detection and signal processing~
The invention is preerably used in such applications,
where a magnetic card reader, which genera-tes an F2F (NRZI)
code, or an optical bar code reader is used as the signal
source.
The advantage of the computer system according to
this invention over prior art resides in the fact that
full use is made of the various computers on the dif-
ferent levels. The use of the up and down counting
apparatus within the micro computer makes it possible to
save computing time, which time may be used for assem-
bling data, error checking routines, etc. within amicro computer. The use of table memories in the ter-
minal computer enables checking the validity of the in-
put signals in order to create output signals at the
terminal computer without the need to activate the
host computer in each separate case. The inventionfurther enables updating the table data in th~ terminal
computer through the keyboard, which means that the
terminal computer can work independently without any
help from the host computer. Further the invention en-
ables a selective reduction of the freedom for the ter-
minal computer to influence table data, if the host
computer considers this freedom not to be given to the
terminal computer.
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l The use of adapter and connector circuits between
the various computex levels enables a deyree of indepen-
dence for the various computer levels, which may be
adapted to the area of application. This is especially
advantageous if the system is used in connection with
classified entrance checking.
The invention will be described in detail with re-
ference to the accompanying drawings.
Fi~. l is a schematic diagram of a hierarchical
computer system according to the present invention.
Fig. 2 discloses the constructing of the micro
computers in fig~
Fig. 3 is a timing diagram for the signal detection
in a micro computer according to fig. 2.
Referring to Fig. 1 a terminal computer 27 com-
prises a control unit 1, which is connected through a
memory channel 4 to a storage 2 and a read only memory
3 as well as through an input/ou~put channel 5 to a
plurality of input/out d~vices represented by a key~
board 8, a display 10, a number of micro computers 22
and a number of output devices 26. Moreover, the con-
trol unit l is connected through its input/output chan-
nel 5, an adapter ll, a line connection 13 and a trans-
mission channel 14 to a host computer 15~ The host
computer 15 is also connected through other transmission
channels 14 to other similar terminal computers 27.
The keyboard 8 is conn~cted through a keyboard con-
nection 7 and an adapter 6 to the input/output channel
5. Similarily the display lO is connected through a
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1 display interface 9 and the adapter 6 to the input/
output channel 5 and thus to the control unit 1~ Each
one of a number of signal sources 23 is connected to
a micro computer 22, which through a digital in adap-
ter 18 is connected through a digital channel 17, achannel interface 16 and the input/output channel 5 to
the control unit 1. Similarly the output devices 26
are connected through a digital out adapter 20, the
digital in/out channel 17, the channel interface 16 and
the input/output channel 5 to the control unit 1. The
control unit 1 can further communicate through the
input/output channel 5, the adapter 11 and a line
interface 12 with external modulators/demodulators for
transmission lines.
As to the function of the system in Fig. 1 the host
computer 15 initially loads control data through the
transmission channel 14, the line interface 13, the
adapter 11 and the control unit 1 into the control mod-
ules 2A, 2B, 2C, 2D and 2E of the storage 2. Alter
natively or as a complementory function certain control
data may also be loaded through the keyboard 8, the
keyboard interface 7, the adapter 6 and the control
unit 1 into the modules A, B, C, D and E of the stor-
age 2.
When the terminal computer 27 has been loaded with
control data it is ready to receive signals from the
signal sources 23 and to influence the output devices
26 according to these signals and with regard to the
stored control data. When a signal source 23 starts
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1 sending input signals to its associated micro computer
22, these input siynals are detected and decoded in the
micro computer and assembled to a message in the form of
e.g. a number of characters. The micro computer 22 then
calls the digital in adapter 18, which is controlled by
a digital in/out controller 19, in order to transmit
the message to the digital in adapter 18. From the
digital in adapter 18 the message is transmitted through
the channel interface 16 and the input/output channel 5
to the con~rol unit 1. The control unit 1 compares the
message with the stored control data in the storage
modules A, B, C, D and E in order to decide whether the
message is a valid message and whether this message is
to cause an activation of an output device 26. If that
is the case the control unit 1 sends a corresponding out-
put message through the in/out channel 5, the channel
connection 16, the digital output adapter 20, which is
as well controlled by the digital in/digital out control-
ler 19, to a chosen output device 26 that then is acted
upon.
The system according to Fig. 1 can operate in dif
ferent modes. In a first operating mode the terminal com-
puter 27 operates substantially independently when it is
once loaded from the host computer 15. The terminal
operator has access to the keyboard 8 and the display 10.
On the display 10 the operator can follow the influence
on the system from the incoming messages from the signal
sources 23 and the micro computers 22 to the control unit
1. Through the keyboard 8 the operator then may change
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1 or update the control data in the control modules A-E of
the storage 2.
In the second operating mode of the system the
operator cannot change the control data in the storage
2 through the keyboard 8 and the display 10. All control
data changes are made from the host computer 15 through
the communication channel 14. However, the operator is
able to communicate with the host computer and to receive
information from as well as deliver information to the
host computer 15 through the control unit 1.
A third mode of operation combines the operation
modes 1 and 2 in such a way that the operator is able to
update certain information in the control data of
storage 2.
Fig. 2 illustrates the micro computers 22 and the
signal sources 23. A micro computer 22 comprises a micro
control unit 35, an arithmetic logic unit 36, a micro
storage 37 and a number of gates 41 and 42. An internal
channel 43 interconnects the various units o~ the micro
computer. The micro control unit 35 i5 further connected
to the signal source 23 through a conductor 24, to the
digital in adaptex 18 through a conductor 33 for inp~t
signals and to the digital in adapter 18 through an out-
put conductor 31 for output signals. The gate 42 is
connected to the digital in adapter through an output
data channel 34, and the gate 41 is connected to thedigital in adapter 18 through an input address channel 32.
A number of micro computers 22 with associatPd signal
source 23 can be coupled in parallel to the digital in
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-
adapter through the data channel 34, the address channel
32 and the input and output control conductors 31 and 33.
The following is a description of the operation of
the micro computer 22 for receiving signals from ~he sig-
nal source 23 as well as decoding and assembling this sig-
nal data. Reference will be made to the timing diagram of
Fig. 3.
It is assumed that the signal source 23 issues sig-
nals, the form of which is shown on line A for the input
pulse in Fig. 3. This signal form is called a F2F code,
whereby a zero value for the signal during a time inter-
val is represented ~y a constant signal level, whereas a
l value is represented by a change in signal level during
a time interval.
The micro stor~ge 37 of the micro computer 22 com-
prises three main parts: a decoder 40, a data storage 38
and a register storage 39.
With reference to Fig~ 3 the input pulse changes its
level from a low value to a high value at time 10 on the
time line T. The micro control unit 35 recognizes this
level change which occurs on the conductor 24 from the
signal source 23.
The operations start one time interval earlier
at time T=O (not shown) when a pulse counter within the
micro computer 22 starts counting up from the value 0.
In Fig. 3 this pulse counter is shown on line B. At
time T=lO this pulse counter has reached a maximum v~lue.
Within the micro computer 22 this pulse counter is re-
presented by a register Rl in the register storage 39
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1 according to Fig. 2. The contents of the register Rl
will be coun~ed up continuously through the arithmetic
logic unit 36 in a conventional way. At time T=10, the
pulse counter having reached its maximum value, the
arithmetic logic unit 36 calculates a 3/4 value of the
pulse counter's maximum value. This 3~4 value is stored
- in another register, e.g. R2 within the register storage
39. At the same time this 3/4 value i5 also stored in
the pulse counter Rl. From this time 10 on the pulse
counter Rl starts counting do~l. At time T=16 the pulse
counter reaches the value zero. This time is used for
detecting the signal level of the input signals. From
Fig. 3 it is seen that the input signal has a high value
at time T16. This high value is stored in one more regis-
ter, e.g~ register R3 within the register storage 39.At time T16 also the contents of register R2 is returned
to the register Rl. Now the pulse counter Rl has again a
3/4 value of its maximum value. From this time on, the
pulse counter Rl starts counting up again until a level
change occurs in the input pulse, which will take place
at time T20. At this time the 3/4 value of the contents
of the pulse counter Rl will again be calculated in the
arithmetic logic unit 36. The new 3/4 value is stored
in the register R2. From this 3/4 value one more con-
stant K is subtracted, and the result is stored in Rl.The constant K corresponds to a given counting down time
for the pulse counter Rl; according to Fig. 3 the con-
stant K corresponds to for instance two timP units. This
means that the pulse counter Rl does not have to start its
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1 counting down at time T20 but at time T22. During the
time interval ~etween T20 and T22 the micro computer can
ex~cute other tasks. In other words it may process data,
which is shown on line E in Fig. 3. At time T22 the
pulse counter Rl starts counting down from a value which
is 3/4 of the maximum value reduced by K.
According to Fig. 3 the input pulse changes its level
from a low value to a high value at time 24. At time 26
a pulse counter Rl reaches the value zero~ At this time
a higher value is detected for the input pulse. The
micro control unit 35 now initiates a comparison in the
arithmetic logic unit 36 between the earlier stored in-
put pulse value from register R3 and the current input
pulse value. When the values are`equal, the current in-
15 put pulse has a value of 1. Fig. 3 shows that the input
pulse during the time interval between T20 and T30 has
the value 1. At time T26 the pulse counter Rl is re-
loaded with the 3/4 value from the register R2, where-
after the pulse counter Rl starts counting up.
At time T30 the input pulse changes its level from
high to low. The pulse counter Rl then stops at its
maximum value, at which time a new 3/4 value is calcu-
lated and the constant K subtracted. Between time T30
and T32 data is processed according to line E in Fig. 3.
From time T32 on, pulse counter Rl starts counting down,
which is illustrated on line D in Fig. 3. At time T36
the pulse counter Rl reaches zero level, at which time
the input pulse level is detected. In this case the
input pulse has a low value. The earlier detected input
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1 pulse level, which has been stored in R3, is compared
to the current level in arithmetic logic unit 36. In
this case the levels are not equal, which means that the
detected input signal has the value zero. It is seen in
Fig. 3 that the input signal has the value zero during
the time interval T30 to T40. At time T36 the value for
the latest input pulse level is reloaded in the register
R3, that is the value of a low input pulse signal. At
time T36 the input pulse counter R1 is also loaded with
the 3/4 value from the register R2, whereafter the pulse
counter Rl starts counting up. This is shown on line C
in Fig. 3. At time T40 the input pulse changes its
level, the pulse counter stops and the 3/4 value is cal-
culated and transferred to the register R2. The constant
X is subtracted and the result is stored in Rl. The data
processing occurs during the time interval T40 to T42
according to line E, whereafter the pulse counter counts
down according to line D and a new level detection is
carried out at time T46.
In this way the micro computer 22 is able to con-
tinuously detect the input pulses from the signal source
23. It should be noted that the counter value 3/4 of the
maximum value has been chosen in order to have the prob-
ability of this signal level detection as high as pO5-
sible when using the F2F code. This is clearly shown
at time 26 in Fig. 3.
It should further be noted that, if the time inter-
val between level changes for the input pulse increases
or decreases, then the detection point follows this
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~ 1S7S7(~
.
1 change due to the fact that the detection point is cal-
culated starting from the 3/4-value for the total value
of the pulse counter. However, the computing time of the
micro computer will always be the same owing to the con-
stant K.
According to Fig~ 3, line E represents the timeavailable for data computing within the micro computer.
During this ~ime period the micro computer assembles in-
put data from the signal source 23, calls the digital in
adapter 18, receives signals from digital in adapter 18
and transmits data on data channel 34 to the adapter.
A specific embodiment of the invention in the form
of a system for attendance and entrance checking will
now be described.
The system comprises an installation, where a number
of magnetic card readers are arranged at convenient places
within a building in order to register the attendance
time for the employees working in the building and to al-
low selective entrance to certain people through certain
watched doors. Each individual then has a personal
identity card in the form of a magnet batch ~ard, which
he or she puts into the magnetic card reader when pas-
sing this reader. The magnetic card reader reads the
identity number on the card, whereafter the system re-
cords the entrance time and the identity number and pos-
sibly opens a corresponding entrance door. The input of
a magnetic card may further light a signal lamp.
In connection with such a system for attendance
and entrance control a number of dif~erent alternatives
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. .
1 are possible. It may for i~stance be desirable that
certain magnetic cards can only be used when checking
the attendance, while other magnetic cards may be used
for getting entrance to locked areas. It can further
be desirable that the entrance to locked areas is
divided into selective classes, that the system has
certain routines regarding lost magnetic cards and
that the possibility exists to detect unvalid cards and
so on. In order to meet these requirements the system
is built according to what is called a classification
checkin~ system.
The above mentioned classification adapted system
works in such a way that according to Fig. 1 the main
computer 15 first of all sends a number of tables to
the memory 2 of the terminal unit 27. The very first
table, consisting of a magnetic card class table, is
stored in what is called a screen storage 2A within
the memory 2. ~n example of such a class table is
shown below (table 1).
Table 1
_
Signal source 1 2 3 4 5 6 7 8
Class 0 1 2 3 2 4 10 7
Output Device 1 4 5 6 7 8 0 3
Output Time 10 15 15 30 20 2 15
Message Host Computer 0 1 1 3 3 3 2 2
Message Terminal0 2 3 2 1 1 3 3
The first line of this table indicates the signal
source number, that is the number of the magnetic card
reader. It is supposed that there are eight ma~ne-tic
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1 card readers which in Fig. 1 are represented by the
signal sources 23. The second line shows the class
number. According to the example above all available
magnetic cards are divided into ten classes. Which
cards belonging to which classes is indicated in table
2 that will be explained later on.
The third line indicates the sequence number of
the output device. Accordingly it can be seen that the
first signal source or the first magnetic card reader
acts upon the first output device. It can further be
seen that the fourth signal source acts upon the sixth
output device. This action may be the opening of a
door, the lighting of a lamp or the closing of a con-
tact.
The fourth line tells us for how long time (seconds)
the output device is acted upon. Accordingly it can be
seen, for instance, that the third signal source is
acting upon the output device 5 during 15 seconds.
The ifth line gives the condition for the sending
of a message to the host computer, and the sixth line
gives the corresponding conditions for showing the
message on the terminal display. The message lines 5
and 6 are divided into four error classes. Error class
0 means; when a magnetic card is inserted into a mag-
netic card reader, that is into a signal source, nothingis to be reported even if an error occurs. If the error
class has the value of 1 only such errors are reported
that indicate the use of a card which earlier has been
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:: 7 ~757~
1 reported to be lost. Error class 2 means that both
lost cards and invalid cards are reported, i.e.also
errors due to the use o a card outside the card class
that according to line 2 of table 1 is allowed for the
corresponding magnetic card reader.
When the host computer 15 during an initiating
phase state is loading the table 1 into the screen
storage 2~, the host computer will further transmit
other table screens to the screen storages 2B, 2C, 2D
and 2E. These table screens comprise of a card class
index table in the form of a table 2, which is stored
in the screen storage 2B. The third table consists of
a specific card class table and is stored in the screen
storage 2C. The fourth table consists of a message
report to the host computer and is stored in the screen
storage 2D. The fifth table consists of error messages
for the terminal and is stored in the screen storage 2E.
The tables 1-5 are transferred from the host com-
puter to the terminal screen storages 2A-2E in such a
form that their information is easily available to an
operator working at the terminal keyboard 8 and its
display 10. This means that the table fields are e~uip-
ped with what is known in the art as attribute charac-
ters, which define the position of a field on the dis-
play. Accordingly it is easy for an operator to getaccess through the cursor of the keyboard and the dis-
play to any position or any field whatsoever within a
table. Such tables are also called screens and axe
very easy to use for the operator.
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.,
1 One example of a card ~lass index table is shown in
table 2 below.
Table 2
S2 CL00 00000-15000 CL06 10110-10150
CL01 10000-10100 CL07 10200-10300
CL02 10000-10500 CL08 11000-11500
CL03 10500-10999 CL09 12101-12200
CL04 12000-12600 CL10 12000-15000
CL05 13000-13999
In this example it is supposed that the total num-
ber of magnetic cards are 15000. The card class zero
comprises all these cards. The card class one com-
prises only one hundred cards, i.e. all magnetic cards
between the values of 10000-10100. The card class two
comprises 500 cards, defined by the card numbers be-
tween 10000 and 10500 and so on for the remaining card
classes.
Going back to table 1 it can be seen that for in-
stance the signal source number eight, i~e. the mag-
netic card reader number eight, accepts only the cardclass seven, i.e. magnetic cards with identity number
between 10000 and 10300, as valid cards. If such a
card is put into the signal source number eight, the
output device number three is acted upon during 15
seconds. If a card outside class seven is put into
the signal source number eight, this will be reported
as an error to the terminal display due to the error
code 3. However, this error is not reported to the
host computer owing to the error code 2 on line S of
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1 the table 1. If, however, a card that is invalid or a
card that has been reported "lost'l would be put into
the signal source 8, this fact too would be reported to
the host computer.
The third table is stored in the screen storage 2C
and is ~ listing of all valid magnetic cards yrouped
according to card class. To start with all cards are
considered invalid, but, depending on which system is
used, the host computer or the terminal operator may
~ive validity to the various cards. In such a way a
validity table 3 can be set. Below is an example of
table 3 for card class 4.
Table 3
S3 04 12345-A12346-B12350-C12368-B
12370-B12375-~12376-B12379-A
12390-B12392-B12394-B12396-B
12398-A12400-A12405-A12410-C
12420-A12430-A12440-B12450-B
12500-A12510-A12520-A12600-B
According to table 2 it is seen that card class 4
comprises cards with identity numbers 12000 and 12600,
corresponding to the numbers in table 2.
Each card number in the above table 3 has been
given a further note A, B or C The letter A means a
valid card, the input of which into a magnetic card
reader always is to be recorded. The letter B means
a card which is not to be recorded, and the letter C
means a card which has been reported "lost". It is
also possible to use the letter D for invalid cards
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.
1 Accordingly an identity number for a card in table 3 can
be changed lnto invalid by attaching the letter D in-
stead of an earlier letter A-C.
The fourth table is a listing of error messages for
5 the main computer. An example of table 4 is shown below.
Table 4
S4 Message 1 Message 7
Message 2 Message 8
Message 3 Messaye 9
Message 4
Message 5
Message 6
A message in the above table consists of five charac-
ters for the identity card number, four characters for
the time in hours and minutes and one character for in-
dicating the error time. Going back to table 1 it can
be seen that for instance for signal source number one
no message will ever be input into table 4 due to the
fact that the message to the main computer has the error
code number 0. It can further be seen that from the
signal source 2 an erroneous message can only be input
inio table 4 if somebody has tried to use a magnetic
card which has been reported as a lost card. From the
signal source 4, however, all erroneous inputs of mag-
netic cards are reported to the table 4.
Table 5 is an error table regarding messages tothe terminal.
SW9-79-001 -19-
5 ~ û
1 Table 5
. .
S5 Error 1 Error 6
Error 2 Error 7
Error 3 Error 8
Error 4 Error 9
Error 5 Error 10
The error message has the same form as the messages
of table 4. Thus, a message in table 5 comprises notes
about identity number, time and type of error. Besides
the error types mentioned in accordance with table 4,
table 5 may also include further error types, i.e. the
host computer has not loaded correct tables into the
screen storages 2A-2E, if the message table 4 or the
error table 5 is full and so on.
When the system is used for attendance control it
is necessary that a time indication be recorded in con-
nection with the input of a magnetic card into a mag-
netic card reader. This time indication is generated in
such a way that the host computer in connection with, the
loading of the screen tables also sends an initial time
indication to the terminal 27. Thereafter this initial
time is updated every second from a day time clock in
the terminal, which delivers an impulse every second.
This time clock is conveniently provided in the storage
2 of the terminal 27.
According to fig. 1 the generation of input signals
to output devices 26, depending upon input signals from
signal sources 23, will now be described.
The operation starts when a person passing a mag-
netic card reader puts his/her magne~ic card into the
SW9-79-001 -20-
7 5 7 0
1 reader. According to fig. 2 this means that a magnetic
card is inserted into a signal source 23. The signal
source then starts sending signals to the micro control
unit 35 of the micro computer 22 over the line 24 as
described previously. This signal transmission results
in zeroes and ones being recorded in the micro computer
as described in connection with fig. 3 and fig. 2. The
zeroes and ones that have been read are preferably
loaded into a register R4 within the register memory 39.
At this time the micro computer 22 also reads and re
cords start characters, end characters, checks the parity
and so on. This mean~ that the micro computer 22 in-
dependently reads a messagP from a magnetic card and
checks its signal validity. All this data computing
takes place during the time indicated on line E in fig.
3 for data computing.
It should be noted that the assembling of input data
from a read magnetic card in a signal source 23 is handled
completely within the micro computer 22 before the ter-
minal 27 i5 called through digital in adapter 18. This
means that if an error occurs when a magnetic card is
read, the terminal 27 will not be called. Instead the
micro computer 22 neglects such an erroneous reading of
a magnetic card. The individual then has to try once
again to put hisjher magnetic card into the magnetic
card reader, which may lead to the recording in the micro-
computer 22 of a valid reading.
When the micro computer 22 records a valid reading
of the contents of a magnetic card ~rom a signal source
SW9-79-001 -21-
1 ~.S7570
123, it calls a terminal 27 through the line 33 -to the
digital in adapter 18. The terminal 27 answers by
initiating, through digital in adapter 18, a service out
signal on line 31 as well as starting an address search
on the address channel 32. When the digital in adapter
18 finds the called micro computer 22 through the
addressing on the address channel 32, the selected micro
computer 22 signals through the signal line 33 that the
correct micro computer 22 has been found.
10The micro computer 22 then transfers the message
read from the magnetic card, which message has been
temporarily stored in the micro store 37, throu~h the
output ga-te 42 and the data channel 34 to the digital
in adapter 18. In fig. 1 it is seen that the message
is further transferred from the digital in adapter 18
through the channel 17 and the channel interface 16 as
well as through the input/output channel 5 to the
control unit 1. In the control unit 1 the input message
is compared with the information of table 1, 2 and ~
within the screen storages 2A, 2B and 2C. It is supposed
that the message comes from a signal source number 6 and
has an identity card value of 12370. From table 2
it is seen that the value of this identity card belongs
to the class number 4. From table 3 it is seen that this
identity card is a B~card, which means that it is valid
and that the time is to be recorded. From table 1 it
is seen that the signal source 6 accepts the influence on
the output device 8 under the condition that the identity
card belongs to class 4. This is in accordance with the
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1 identity card number 12370. Accordingly, the control
unit 1 issues a signal through the channel interface
16 and ~he channel 17 as well as the ~igital o~t adap-
ter 20 to the output device 26 that is represented by
the output device 8. The activation of output device 8
may represent the opening of a locked door or the
lighting of a signal lamp. The identity number 12370
of the magne-tic card and the time of its input into
the signal source 23 are further stored by the control
unit 1 in a further table, a result table within the
storage 2.
If, however, a magnetic card having the identity
number 12371 had been inserted into the maynetic card
reader corresponding to the signal source 6j the terminal
27 would not have accepted this card as a valid magnetic
card, due to the fact that the table 3 does not contain
the identity card number 12371. The control unit 1 then
feeds this message having identity card number 12371 into
the error table 5. At the same time a buzzing sound
reaches the operator from the control unit 1 through
the keyboard 8 indicating that an error has been re-
corded. The operator then calls the table 5 by the key-
board 8, and that table then appears on the display 10.
If no earlier errors have occurred, only the error number
1 of table number 5 has shown up. Now the operator can
correct the error either through inputting the identity
number 12371 as a valid number to the table 3, if the
operator is authorized to do that, or he may make the
inquery to the host computer~
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1S757~
1 Then suppose that a magnetic card having the identi-
ty card value 12350 thereafter is inserted into the mag-
netic card reader 5. This card is read in the same way
as earlier, and the message is transmitted to the con-
S trol device 1. From table 3 it is seen tha~ identity
number 12350 has a character C and is classified as a
'lost' card. This means that an individual is trying to
use a lost card with the magnetic card reader number 6.
This is not allowed according to the system, and an
error code of error class 3 is to be recorded. From
the table 1 it is seen that regarding the signal source
6 an error code 3 should be reported to the host com-
puter as well as to the terminal display. This error
message is sent input as the message number 1 to the
table 4 within the screen storage 2D and as error number
2 to the error table 5 within the screen storage 2E.
Thereafter, the control unit 1 signals, in the same way
as earlier, an error through the keyboard 8 ~o the op-
erator of the terminal 27. Then the operator calls table
5 through the keyboard 8 to be displayed on the screen
10. Provided that the earlier error has not been
corrected by the operator or the host computer, then
two errors will be displayed on the screen 10, that is
error 1 regarding the identity card 12371 and error 2
regarding the identity card 12350. The operator is then
able to take appropriate steps.
While the system is working according to the above
specification, result messages are continually recorded
in the result table within the storage 2 as well as
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1 error messages in the screen table 2D for a host cornputer
and in 2E for the terminal. At appropriate times these
tables may be transferred to the host computer 15 for
updating or computing.
According to what has been stated above a hierarchi-
cal computer system has been described, where a first
computer 22 is working on a base lev~l in order to as-
semble input data, an intermediate computer 27 is working
on an intermediate level in order to compute data and
possibly completely independently control output units
in conformity to input data from the first computer, and
a host computer 15 is selectively supervising the whole
system on an upper level.
It is thu~ seen that the system according to the
invention may be used for other purposes than attendance
and entrance control. The signal sources 23 of fig. 1,
for instance, may consist of optical readers that read
an optical bar code. Such a bar code may consist of
marks that are prin-ted on pleces of material passiny the
optical signal source. Then the system is able to record
the passing pieces of material and take measures accord-
ing to the classification on which the tables within the
screen storages 2A-2E are based.
It is to be noted that an important part of the in~
vention concept resides in the possibility to control
the independent operation of the computers on the dif-
ferent levels.
According to what is stated above the specific use
of an up/down-counter with a fixed available time for
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1 data computing makes it possible for the microcomputer
22 to work more or less independently. If one embodi-
ment requires that the independence of the micro com-
puter is extremely reduced, it is posslble to send every
detected input signal bit direct to the terminal computer
27. If, however, a very high degree of independence for
- the micro computer is desired, it is possible to store
some simple condition data in the micro memory 37 in-
stead of storing it in the screen storages 2A-2C of the
terminal 27. The micro computer may then partly direct
control output devices 26.
In the same way the terminal computer 27 may oper-
ate on an extremely low independence level, if part of
the condition tables are stored in the host computer 15
lS and no changes are allowed from the keyboard 8. On a
level of extremely high independence all condition tables
of the screen storages 2A-2E may be updated and partly
initiated from the keyboard 8. Then the host computer
15 has a mainly statistical purpose.
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