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Claims  |
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We claim:
1. In a method of processing data including a recurring characteristic
mark, the improvement comprising in combination the steps of:
storing said data at storage locations;
establishing a directory of specific locations of stored data including
said characteristic mark;
processing said stored data; and
controlling said processing with the aid of said directory.
2. A method as claimed in claim 1, wherein:
said establishment of a directory includes the step of noting specific
locations at which data including said recurring characteristic mark are
stored.
3. A method as claimed in claim 1, wherein:
said establishment of a directory includes the steps of providing a sample
of said characteristic mark, comparing said data including said recurring
characteristic mark prior to said storage serially with said sample to
detect said recurring characteristic mark, and noting specific locations
at which data including said recurring characteristic mark are stored.
4. In a method of processing data including a recurring characteristic
mark, the improvement comprising in combination the steps of:
storing said data and recurring characteristic mark at storage locations;
establishing a directory of specific locations at which said recurring
characteristic mark is stored;
processing said stored data and recurring characteristic mark; and
controlling said processing with the aid of said directory.
5. A method as claimed in claim 4, wherein:
said establishment of a directory includes the step of noting specific
locations at which said recurring characteristic mark is stored.
6. A method as claimed in claim 4, wherein:
said establishment of a directory includes the steps of providing a sample
of said characteristic mark, comparing said data including said recurring
characteristic mark prior to said storage serially with said sample to
detect said recurring characteristic mark, and noting specific locations
at which said recurring characteristic mark is stored.
7. In a method of processing data quanta characterized by delimiter marks,
comprising in combination the steps of:
storing said data quanta at storage locations;
establishing a directory of specific locations of stored data including
said delimiter marks;
retrieving said stored data quanta from said storage locations; and
identifying said data quanta with the aid of said directory.
8. A method as claimed in claim 7, wherein:
said establishment of a directory includes the step of noting specific
locations at which data including said delimiter marks are stored.
9. A method as claimed in claim 7, wherein:
said establishment of a directory includes the steps of providing a sample
of said delimiter marks, comparing said data including said delimiter
marks prior to said storage serially with said sample to detect said
delimiter marks, and noting specific locations at which data including
said delimiter marks are stored.
10. In a method of processing data quanta characterized by delimiter marks,
comprising in combination the steps of:
storing said data quanta and delimiter marks at storage locations;
establishing a directory of specific locations at which said delimiter
marks are stored;
retrieving said stored data quanta and delimiter marks from said storage
locations; and
identifying said data quanta with the aid of said directory.
11. A method as claimed in claim 10, wherein:
said establishment of a directory includes the step of noting specific
locations at which said delimiter marks are stored.
12. A method as claimed in claim 10, wherein:
said establishment of a directory includes the steps of providing a sample
of said delimiter marks, comparing said data including said delimiter
marks prior to said storage serially with said sample to detect said
delimiter marks, and noting specific locations at which said delimiter
marks are stored.
13. In a method of processing data including a recurring executive mark,
the improvement comprising in combination the steps of:
storing said data at storage locations;
establishing a directory of specific locations of stored data including
said recurring executive mark;
processing said stored data; and
controlling said processing with the aid of said directory.
14. A method as claimed in claim 13, wherein:
said establishment of a directory includes the step of noting specific
locations at which data including said recurring executive mark are
stored.
15. A method as claimed in claim 13, wherein:
said establishment of a directory includes the steps of providing a sample
of said recurring executive mark, comparing said data including said
recurring executive mark prior to said storage serially with said sample
to detect said recurring executive mark, and noting specific locations at
which data including said recurring executive mark are stored.
16. In a method of processing data including a recurring executive mark,
the improvement comprising in combination the steps of:
storing said data and recurring executive mark at storage locations;
establishing a directory of specific locations at which said recurring
executive mark is stored;
processing said stored data; and
controlling said processing with the aid of said directory.
17. A method as claimed in claim 16, wherein:
said establishment of a directory includes the step of noting specific
locations at which said recurring executive mark is stored.
18. A method as claimed in claim 16, wherein:
said establishment of a directory includes the steps of providing a sample
of said recurring executive mark, comparing said data including said
recurring executive mark prior to said storage serially with said sample
to detect said recurring executive mark, and noting specific locations at
which said recurring executive mark is stored.
19. In a method of processing data including a recurring error, the
improvement comprising in combination the steps of:
storing said data including said recurring error at storage locations;
establishing a directory of specific locations at which said recurring
error is stored;
processing said stored data; and
eliminating said recurring error with the aid of said directory.
20. A method as claimed in claim 19, wherein:
said establishment of a directory includes the step of noting specific
locations at which said recurring error is stored.
21. A method as claimed in claim 19, wherein:
said establishment of a directory includes the steps of providing a sample
of said recurring error, comparing said data including said recurring
error prior to said storage serially with said sample to detect said
recurring error, and noting specific locations at which said recurring
error is stored.
22. In apparatus for processing data including a recurring characteristic
mark, the improvement comprising in combination:
first means including storage locations for storing said data;
second means operatively associated with said first means for establishing
a directory of specific locations of data stored in said first means
including said characteristic mark;
third means connected to said first means for processing said stored data;
and
fourth means connected to said second and third means for controlling said
processing with the aid of said directory.
23. Apparatus as claimed in claim 22, wherein:
said second means include means for noting specific locations at which data
including said recurring characteristic mark are stored in said first
means.
24. Apparatus as claimed in claim 22, wherein:
said second means include means for providing a sample of said recurring
characteristic mark, means connected to said sample providing means for
comparing said data including said recurring characteristic mark serially
with said sample to detect said recurring characteristic mark, and means
for noting specific locations at which data including said recurring
characteristic mark are stored in said first means.
25. Apparatus as claimed in claim 22, wherein:
said apparatus include a repository of said data including said recurring
characteristic mark;
said apparatus further includes means for transferring said data including
said recurring characteristic mark from said repository to said first
means for storing said data; and
said second means include means for providing a sample of said
characteristic mark, means connected to said sample providing means for
comparing said data including said recurring characteristic mark during
said transfer serially with said sample to detect said recurring
characteristic mark, and means for noting specific locations at which data
including said recurring characteristic mark is stored in said first
means.
26. In apparatus for processing data including a recurring characteristic
mark, the improvement comprising in combination:
first means including storage locations for storing said data and recurring
characteristic mark;
second means operatively associated with said first means for establishing
a directory of specific locations at which said recurring characteristic
mark is stored;
third means connected to said first means for processing said stored data;
and
fourth means connected to said second and third means for controlling said
processing with the aid of said directory.
27. Apparatus as claimed in claim 26, wherein:
said second means include means for noting specific locations at which said
recurring characteristic mark is stored in said first means.
28. Apparatus as claimed in claim 26, wherein:
said second means include means for providing a sample of said recurring
characteristic mark, means connected to said sample providing means for
comparing said data including said recurring characteristic mark serially
with said sample to detect said recurring characteristic mark, and means
for noting specific locations at which said recurring characteristic mark
is stored in said first means.
29. Apparatus as claimed in claim 26, wherein:
said apparatus include a repository of said data including said recurring
characteristic mark;
said apparatus further include means for transferring said data including
said recurring characteristic mark from said repository to said first
means for storing said data; and
said second means include means for providing a sample of said
characteristic mark, means connected to said sample providing means for
comparing said data including said recurring characteristic mark during
said transfer serially with said sample to detect said recurring
characteristic mark, and means for noting specific locations at which said
recurring characteristic mark is stored in said first means.
30. In apparatus for processing data including a recurring error, the
improvement comprising in combination:
first means including storage locations for storing said data including
said recurring error;
second means operatively associated with said first means for establishing
a directory of specific locations at which said recurring error is stored;
third means connected to said first and second means for eliminating said
recurring error with the aid of said directory.
31. Apparatus as claimed in claim 30, wherein:
said second means include means for noting specific locations at which said
recurring error is stored.
32. Apparatus as claimed in claim 30, wherein:
said second means include means for providing a sample of said recurring
error, means connected to said sample providing means for comparing said
data including said recurring error serially with said sample to detect
said recurring error, and means for noting specific locations at which
said recurring error is stored.
33. Apparatus as claimed in claim 30, wherein:
said apparatus includes a repository of said data including said recurring
error;
said apparatus further includes means for transferring said data including
said recurring error from said repository to said first means for storing
said data;
said second means include means for providing a sample of said recurring
error, means connected to said sample providing means for comparing said
data including said recurring error during said transfer serially with
said sample to detect said recurring error, and means for noting specific
locations at which said recurring error is stored. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention relates to data processing and, more specifically, to
the processing of data including a recurring characteristic mark or error
which during further processing is to be acted on or eliminated.
2. Description of the Prior Art
Despite the rapid advance of electronic data processing and computer
technology in recent years, there persists a need for a more rapid
recognition of recurring characteristic marks or errors. For instance, a
rapid recognition of delimiter marks is required in many instances where
this is necessary to an identification of word or line lengths. Similarly,
a rapid recognition of shift codes is required where data or its display
is to be shifted during data processing. A rapid recognition of recurring
errors is also required in error elimination routines.
By way of example, and not by way of limitation, reference may be had to
computer output microfilm (COM) equipment. Most computer installations
have many applications for which there is a very large printout to be used
for reference purposes. Such printouts are bulky, take large storage space
and are difficult to access. By the use of COM equipment, wherein data is
displayed on a cathode ray tube (CRT) the screen of which is exposed to
microfilm, a microfilm copy of the output either as a roll or as a
microfiche is produced. The speed of recording is many times faster than
printing and additional microfilm copies may be made at very low cost.
On the other hand, the attainable or potential rapid speed of recording
requires a very rapid recognition of record marks which delimit each line,
for a rapid line-by-line display of the output. By way of further example,
a rapid recognition of shift marks is required for frequent shifts in the
display between lower and upper case representation.
A similar need exists in applications wherein a recurring error is to be
detected and rapidly eliminated.
So far the emphasis in the area under consideration has been on the
improvement of programing or software. In brief, programs and software
were perfected to effect a character-by-character search of processed data
to detect characteristic marks therein. Upon detection of each mark, the
particular data shifting process had to be interrupted so that the
detected mark could be acted upon. The result was not only an extensive
complication of the computer program, but also a significant reduction of
the overall data processing speed because of the time required to effect
the various subroutines and because of the delays brought about by the
latter frequent interruptions.
SUMMARY OF THE INVENTION
It is a general object of this invention to overcome the above mentioned
disadvantages.
It is a germane object of this invention to reduce the volume of software
in data processing systems. It is a further germane object of this
invention to provide novel hardware for data processing systems.
It is a further germane object of this invention to increase the speed of
data processing.
It is also an object of this invention to provide improved computer output
microfilm equipment.
It is also an object of this invention to provide improved apparatus and
methods of processing data including a recurring characteristic mark.
It is a further object of this invention to provide improved methods and
apparatus for processing data including a recurring error.
Other objects will become apparent in the further course of this
disclosure.
From one aspect thereof, the subject invention resides in a method of
processing data including a recurring characteristic mark and, more
specifically, resides in the improvement comprising in combination the
steps of storing the data at storage locations, establishing a directory
of specific locations of stored data including the characteristic mark,
processing the stored data, and controlling the processing with the aid of
the established directory.
From a related aspect thereof, the subject invention resides in apparatus
for processing data including a recurring characteristic mark and, more
specifically, resides in the improvement comprising, in combination, first
means including storage locations for storing the data, second means
operatively associated with the first means for establishing a directory
of specific locations of data stored in the first means including the
characteristic mark, third means connected to the first means for
processing the stored data, and fourth means connected to the second and
third means for controlling the processing with the aid of the established
directory.
From another aspect thereof, the subject invention resides in a method of
processing data including a recurring characteristic mark and, more
specifically, resides in the improvement comprising in combination the
steps of storing the data and recurring characteristic mark at storage
locations, establishing a directory of specific locations at which the
recurring characteristic mark is stored, processing the stored data and
recurring characteristic mark, and controlling the processing with the aid
of the established directory.
From a related aspect thereof, the subject invention resides in apparatus
for processing data including a recurring characteristic mark and, more
specifically, resides in the improvement comprising, in combination, first
means including storage locations for storing the data and recurring
characteristic mark, second means operatively associated with the first
means for establishing a directory of specific locations at which said
recurring characteristic mark is stored, third means connected to the
first means for processing the stored data, and fourth means connected to
the second and third means for controlling the processing with the aid of
the established directory.
From another aspect thereof, the subject invention resides in a method of
processing data quanta characterized by delimiter marks and, more
specifically, resides in the improvement comprising in combination the
steps of storing the data quanta at storage locations, establishing a
directory of specific locations of stored data quanta including the
delimiter marks, retrieving the stored data quanta from the storage
locations, and identifying the data quanta with the aid of the established
directory.
From another aspect thereof, the subject invention resides in a method of
processing data quanta characterized by delimiter marks and, more
specifically, resides in the improvement comprising in combination the
steps of storing the data quanta and delimiter marks at storage locations,
establishing a directory of specific locations at which the delimiter
marks are stored, retrieving the stored data quanta and delimiter marks
from the storage locations, and identifying the data quanta with the aid
of the established directory.
From another aspect thereof, the subject invention resides in a method of
processing data including a recurring executive mark and, more
specifically, resides in the improvement comprising in combination the
steps of storing the data at storage locations, establishing a directory
of specific locations of stored data including the recurring executive
mark, processing the stored data, and controlling the processing with the
aid of the established directory.
From another aspect thereof, the subject invention resides in a method of
processing data including a recurring executive mark and, more
specifically, resides in the improvement comprising in combination the
steps of storing the data and recurring executive mark at storage
locations, establishing a directory of specific locations at which the
recurring executive mark is stored, processing the stored data, and
controlling the processing with the aid of the established directory.
From yet another aspect thereof, the subject invention resides in a method
of processing data including a recurring error and, more specifically,
resides in the improvement comprising in combination the steps of storing
the data including the recurring error at storage locations, establishing
a directory of specific locations at which the recurring error is stored,
processing the stored data, and eliminating the recurring error with the
aid of the established directory.
From a related aspect thereof, the subject invention resides in apparatus
for processing data including a recurring error and, more specifically,
resides in the improvement comprising, in combination, first means
including storage locations for storing the data including the recurring
error, second means operatively associated with the first means for
establishing a directory of specific locations at which the recurring
error is stored, third means connected to the first and second means for
eliminating the recurring error with the aid of the established directory.
BRIEF DESCRIPTION OF THE DRAWINGS
The subject invention and its aspects and objects will become more readily
apparent from the following detailed description of preferred embodiments
thereof, illustrated by way of example in the accompanying drawings, in
which like reference numerals designate like or functionally equivalent
parts, and in which:
FIG. 1 is a block diagram of data processing equipment in accordance with a
preferred embodiment of the subject invention; and
FIG. 2 is a functional block diagram of the data processing equipment shown
in FIG. 1, in accordance with a further preferred embodiment of the
subject invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
The data processing equipment 10 shown in FIG. 1 is shown with a repository
of data, such as a magnetic tape 12 or other data storage facility. A
length of magnetic tape 13 or another data recording medium is
symbolically shown in FIG. 1 as containing quanta 14 of recorded data
including a recurring characteristic mark 15.
Data reproduced from the tape 12 is simultaneously applied to a data
transfer logic 16 and to a comparison logic 17. The data transfer logic
may be of a conventional type providing and applying the reproduced data
to a data storage facility or memory 18 via a data bus 19, and for
providing at an output 21 also the addresses of the stored data. The data
processing equipment 10 further includes a central processing unit (CPU)
for controlling the operation of the equipment. The CPU may be of a
conventional type, including a primary memory for holding instructions to
be executed and data to be used, an arithmetic unit, and a control unit
for operating the system as directed by the instructions.
The data processing equipment 10 further includes a register facility 24
for providing and storing a sample of the characteristic mark or error to
be detected.
The comparison logic 17 may also be of a conventional type for comparing
the data including the recurring characteristic mark or error during
transfer from the tape 12 to the data transfer logic 16 serially with the
sample in the register facility 24 to detect the recurring characteristic
mark or error.
Each time a characteristic mark or an error corresponding to the sample in
the register facility 24 has been detected, the comparison logic 17 issues
a comparison acknowledgment signal via a line 26 to a directory register
facility 27. The facility 27 has an input connected via a line 28 to the
address output 21 of the data transfer logic 16. The directory facility 27
thus receives the addresses provided by the data transfer logic 16 and, in
response to each comparison acknowledgment signal received from the
comparison logic 17 via the line 26, stores the address of the particular
data which has matched the sample at 24.
For instance, if the sample at 24 is a recurring characteristic mark, then
the directory register facility 27 would store the address of each such
characteristic mark upon its detection by the comparison logic 17, until
there has been established at 27 a directory of specific locations of data
stored in the memory 18 including the particular specific mark.
On the other hand, if the sample at 24 is a sample of a recurring error,
then the register facility 27 stores the address received via line 28 of
each error detected by the comparison logic 17 and signaled via line 26.
The register facility 27 proceeds in this fashion as the comparison logic
17 serially compares the data transferred from the tape 16, until the
register facility 27 contains a directory of specific locations at which
the recurring error corresponding to the saple at 24 is stored in the
memory 18.
In practice, the data or characters corresponding to the sample at 24 may
or may not be stored in the memory 18. For instance, if the sample at 24
corresponds to a recurring characteristic mark, then that mark may itself
be stored in the memory 18 and the directory facility 27 would then
provide and store a directory of the specific locations or addresses of
that stored recurring mark in the memory 18. On the other hand, the
recurring characteristic mark, upon its detection by the comparison logic
17, may be deleted in the data transfer logic 16 and would in that case
not be stored in the memory 18. The directory facility 27 would then
provide a directory of specific locations or addresses of data stored in
the memory 18 and pertaining to the recurring characteristic mark.
For instance, if the recurring characteristic mark is a line delimiter mark
which signifies the end of each line to be displayed by the CRT of a COM,
then it would in principle suffice for the directory facility 27 to
provide a directory of storage locations or addresses containing the end
of a line. Such a directory at 27 would then be equivalent to a directory
of storage locations or addresses of delimiter marks in the memory 18
itself.
A delimiter or other characteristic mark may be associated with a data
quantum comprised of a predetermined number of bits. These data quanta
may, for instance, be words, bytes, or lines.
The hardware shown in FIG. 1 also includes a directory status facility or
logic 31 connected to the directory 27 and to the bus 19 in order to
inform the central processing unit 23 of the status of the directory 27.
In particular, the directory status logic 31 enables the central
processing unit 23 to inform itself whether there are addresses in the
directory 27 at a particular time. If so, the central processing unit 23
would interrogate the directory 27 and obtain all directory information
therefrom, until the directory status logic 31 would inform the central
processing unit 23 that there is no more valid directory information
stored at 27.
In a typical operation, the contents of the directory 27 are transferred to
the memory portion of the central processing unit 23 for easier access.
The central processing unit 23 then is able to control the transfer or
further processing of information from the memory 18. Of course, whenever
the directory status logic 31 indicates to the central processing unit 23
that no or no more directory information is stored at 27, the central
processing unit 23 is free to institute or carry out another operating
cycle.
By way of example, in the case of computer output microfilm display
information reproduced from the tape 12 and transferred to the memory 18,
the central processing unit 23 may cause such stored information to be
transferred from the memory 18 via bus 19 to a data output facility 32 for
display by a cathode ray tube 33 or other display facility which will
permit the establishment of a computer output microfilm record on
photographic film 34 or another appropriate pictorial information
recording medium. Alternatively, or concurrently, the data output facility
32 may apply the information retrieved from the memory 18 to a data
printer 35 for printout.
In either case, it is important for the data output facility 32 to
determine when the CRT 33 or printer 35 has to switch in its display or
printout from one line to the next. This phase of operation generally is
handled with the aid of record or line delimiter marks which signify the
end of each line to be displayed or printed out. Prior-art equipment and
methodology were encumbered by a bottleneck at this juncture. In
particular, the transfer of data from the memory 18 to the display or
printout unit was impeded by the necessity of having to perform a
character-by-character search for the specific tape code, such as a record
mark. This required a considerable expansion of the software and thus
significantly increased the expense of the program as well as the time
consumption of its preparation and performance. It also significantly
limited the efficiency of the hardware participating in the transfer
function.
By solving the problem in the manner herein disclosed, the subject
invention has provided a solution capable of relatively efficient hardware
implementation with corresponding relief of the software, as desired in
particular practical applications.
Of course, software may be made use of whenever desired in a given
application, but such use would still preserve the relief of the software
from the above mentioned character-by-character search during transfer of
the data from the memory 18.
As further shown in FIG. 1, a translator 36, connected to the bus 19, may
be employed for translating the data received from the memory 18 prior to
their application to a data output or other facility operating in a
different language or format. In that case, the principles of the subject
invention may advantageously be employed to recognize characteristic marks
in the data facilitating the operation of the translator 36. In this
connection and also in a general sense, the term "executive mark" has been
coined and is used herein to designate, for instance, an execution code
which may modify the meaning of subsequent data, a shift code in the
latter sense or a shift mark in the sense of an instruction that will
cause the display or printout facility 33 or 35 to shift between upper and
lower case display or printout. In addition or alternatively, the
executive mark within the broad contemplation of the subject invention may
also include a record mark or line delimiter mark of the type already
described above, or any other mark causing execution of some predetermined
function.
For instance, the equipment as shown in FIG. 1 may include an error
elimination facility 38 connected to the data bus 19 for straining out
errors, in a manner known per se, from data retrieved from the memory 18
prior to its application to display or printout equipment or prior to its
further processing. In this respect it is known that many forms of data or
data formats are apt to include errors of a recurring type, such as shift
codes when no shifting is desired or characters that are forbidden in a
given type of information or format. Of course, the error elimination
facility 38 within the broad contemplation of the subject invention need
not be taken literally but may also extend in its operation to equipment
which eliminates recurring characters or marks that are not necessarily
errors in the strict sense. For instance, if executive codes that are
useful in one phase of the data processing operation are no longer needed
in a subsequent phase, they may be eliminated at 38 as if they were
errors. In that case, the facility 24 would again provide a sample of the
character to be eliminated and the comparison logic 17 would cooperate
with the facility 27 to establish a directory of that character so as to
enable the central processing unit 23 to control the transfer of data from
the memory 18 and the elimination thereof at 38 appropriately prior to the
execution of the next data processing or display phase.
As in the case of executive marks, the directory 27, by noting the
locations in the memory 18 at which the particular marks, errors or other
characters to be eliminated are stored, and by making such information
available to the central processing unit 23 or to another processing
facility, obviates a character-by-character software search during the
retrieval of data from the memory 18.
Attention may now be directed to the block diagram of FIG. 2 wherein like
reference numerals as among FIGS. 1 and 2 designate like or functionally
equivalent parts and wherein a further preferred embodiment of the subject
invention is shown.
In particular, the disclosure of FIG. 2 concentrates on the comparison
logic 17, sample storage facility 24, directory 27, directory status logic
31 and related elements, without repeating a showing of such elements as
the memory 18 and components 32, 33, 35, 36 and 38 shown and described in
connection with FIG. 1.
According to FIG. 2, a Recorder Tape Code Comparison or RTCC facility
includes the comparison logic 17 in the form of an A = B comparator 41
which, for instance, may be a magnitude comparator of the type 74LS85 as
described, for instance, on pages 202 to 207 of THE TTL DATA BOOK FOR
DESIGN ENGINEERS, CC-411 (1973), by Texas Instruments Incorporated.
The RTCC also includes a sample register facility 24 including registers 42
which, for example, may be 4 by 4 register files with three-state output
of the type 74LS670 described, for instance, on pages S-332 to S-337 of
the Supplement (CC-416, 1974) of the above mentioned TTL DATA BOOK. The
sample storage facility 24 further includes multiplexers 43 and 44
conventionally available for cooperation with and selection of any of the
registers 42 in the same integrated circuit.
Through the slave control of the computer ("slave" referring to the
reception of information from the CPU I/O bus 19), one or more of the
registers 42 are loaded with the tape byte or character to be searched
for. The registers 42 will be selected in this respect by the multiplexer
receiving a load signal through an input 45 and an address through an
address line 46, in addition to the sample bytes or characters via a line
47. Conventional bus interfacing equipment (not shown) may be employed
between the bus 19 and the RTTC, as desired.
In this manner, one or more of the registers 42 are provided with a sample
of the executive code, error or other character, typically of a recurring
type, to be indexed in the directory 27. In this respect, it should be
noted that more than one sample mark or character may be stored in the
register facility 24 for selective indexing in the directory 27.
The samples are typically provided by the computer in response to one or
more instructions. The samples may be verified or tested via an output
line 51 tied to a tri-state data bus 52.
The tri-state data bus 52 is connectible to the CPU I/O bus 19 via a buffer
or gating circuit 53 switchable by the slave control via an output enable
or OE input.
The address information applied via the line 46 to the multiplexer 43 is
also applied via a line 53 to a stack sequence control 54 in order to
provide in a line 55 Tape Code Comparison or TCC signals for selecting the
appropriate RTCC register 42 via a line 56 and the output multiplexer 44
connected thereto. By way of example, the stack sequence control 54 may
comprise Dual J-K negative edge-triggered flip-flop-elements of the type
74LS112 as shown, for instance, on pages 81, 130 and 131 of the above
mentioned TTL DATA BOOK.
The sample character thus provided is applied via an output line 58 to the
A-input of the comparator 41. Simultaneously, data transferred from the
tape 12 to the memory 18 (see FIG. 1) is also applied via lines 61 and 62
to the B-input of the comparator 51 which is enabled by a compare or CMPR
signal applied by the stack sequence control 54 via a line 64 to the
enable or EN input of the comparator.
Each time a data character transferred to the memory 18 matches the sample
in the register facility 24, the comparator 41 assumes the condition A = B
and issues a match or MTCH signal via line 26 to a write control 65 which,
by way of example may comprise a J-K flip-flop element of the above
mentioned type 74LS112 having the match signal applied to its J-input and
a stack enable signal applied via a line 66 to its clear input in order to
provide a stack write or STKW pulse at its Q output and line 67. The stack
enable or STEN pulse is provided by the directory status logic 31 in a
manner more fully described in the further course of this disclosure.
The start of the tape read cycle with respect to the tape 12 is indicated
by the tape Go signal TGO which will cause a reset logic 69 to reset stack
counters CTR 1 to CTR 4. By way of example, these stack counters may
comprise programmable binary counters of the type DM8556 shown, for
instance, on pages 3-72 to 3-75 of the TTL DATA BOOK by National
Semiconductor Corporation (February 1976).
The stack counters CTR 1 to CTR 4 are controlled by a stack control select
and increment logic 71 which may comprise a Dual Decoder (2-line input to
4-output) of the type 74LS155 shown, for instance, on pages 313 to 316 of
the above mentioned TTL DATA BOOK by Texas Instruments.
An enable pulse provided by the slave control is applied to the enable or
EN input of the stack control 71. The above mentioned Tape Code Comparison
or TCC signal, provided by the stack sequence control 54 is also applied
via a line 72 to the A and B inputs of the stack control 71.
The above mentioned stack write or STKW signal is also applied via the line
67 to the A.sub.IN input of the stack control 71 in response to the above
mentioned match (MTCH) and stack enable (STEN) pulses.
The stack control 71 selects the appropriate counter CTR and increments
same. In the preferred embodiment shown in FIG. 2, four registers 42 and
four stack counters CTR 1-4 are shown. This enables the use of four read
and write memories or RAM's at 74 in the directory 27. By way of example,
these RAM's may be Fully Decoded 256 .times. 4 Static N-Channel RAM
elements of the type Am9101D shown, for instance, on pages 118 and 119 of
the Product Catalog entitled "Outstanding Products" by Advanced Micro
Devices, Inc.
The selected stack counter CTR is output into a tri-state bus 75 which
selects the RAM address in the directory 74 to be loaded in case of a
successful compare at 41. By way of example, the stack counters CTR may be
8-bit counters with only the six least significant bits being used to
address the RAM in the directory 74.
The two most significant RAM address bits are then provided by the same TCC
bits that selected the register 42 in the RTCC via line 56 and the stack
counter CTR 1 to CTR 4 via line 72 and stack control 71.
The hardware shown in FIG. 2 includes a bus address register 76 which
stores recorder tape bus addresses or RTBA. This is in accord with an
advantageous feature of the illustrated preferred embodiment of the
invention which employs bus addresses to index the desired executive mark
or other character. The bus address register 76 is controlled by a load
pulse from the slave control via an LD input and by a tape increment or
TINC pulse from the master control via an INC input. By way of example,
the address register 76 may be a programmable binary counter of the above
mentioned type DM8556.
Whenever a match occurs as signified by the MTCH signal, the stack write or
STKW signal, acting via line 67 on the stack counter 71 and RAM directory
74 will load all the bits of the recorder tape bus address (RTBA) into the
RAM directory 74 at the selected RAM address.
The trailing edge of the stack write or STKW pulse increments the selected
stack counter CTR 1 to CTR 4 to point to the next stack location in the
RAM directory. The stack sequence control 54 will then update the TCC bits
to output the second register 42 in the RTCC, to select the stack counter
CTR 2, and to move the RAM address to correspond to the first word of the
second Code Compare Stack (CCSTK) in the RAM directory 74. The entire
sequence for selecting a register 42 in the RTCC, a stack counter CTR 1 to
CTR 4, a RAM address, and testing equality of the sample to the COM tape
data occurs identically for each of the four stacks CCSTK. After the
fourth stack has been tested, the stack sequence control is reset via a
line 81 and the code compare cycle for that tape byte is complete.
In summary, each time a match of a tape byte with a sample occurs, the
recorder tape bus address (RTBA) is written into a selected RAM address
section assigned in the directory 74. At the same time, that RAM address
provided by the stack counter facility is loaded into a register file 83
in an Empty Detect section of the directory status logic 31. To this end,
the stack write or STKW signal acts via line 67 not only on the RAM
directory 74 but also on a load or LD input of the register file 83.
By way of example, the register file 83 may be a 4 .times. 4 register file
of the above mentioned type 74LS670. In particular, all bits of the
selected stack counter are loaded via a line 85 and a data or D input into
the register file 83. The TCC signal from the stack sequence control 54 is
applied to the select input of the register file 83. The Q output of the
register file 83, in turn, is applied to the B-input of a comparator 87
which may be of the same type as the comparator 41, and which also
receives an enable signal through an enable or EN input. The A-input of
the comparator 87 receives the same information as the D-input of the
register file 83 via line 85. The same applies to a full check logic 89
which, for | | |
