| Company / developer | Don Nelson, Dick Pick, TRW |
|---|---|
| Programmed in | Assembly language |
| Initial release | 1965 (GIRLS), 1973 (Reality Operating System) |
| Marketing target | Business data processing |
| Available language(s) | English |
| Available programming languages(s) | Data/BASIC (BASIC-like), PROC procedure language, ENGLISH |
| Supported platforms | Linux, AIX, Windows Server (2000 and up) |
| Kernel type | Monolithic (or none for operating environment implementations) |
| Default user interface | Text-based |
| License | ? |
The Pick operating system (often called just "the Pick system" or simply "Pick") is a demand-paged, multiuser, virtual memory, time-sharing operating system based around a unique "multivalued" database. Pick is used primarily for business data processing. Though its popularity is diminishing, its capabilities were far ahead of their time and there is still a strong enthusiastic user community.
The term "Pick system" has also come to be used as the general name of all operating environments which employ this multivalued database and have some implementation of Pick/BASIC and ENGLISH/Access queries. Although Pick started on a variety of minicomputers, the system and its various implementations eventually spread to a large assortment of microcomputers, personal computers and mainframe computers and is still in use today.
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The Pick database is a 'hash-file' data management system. A hash-file system is a collection of dynamic associative arrays which are organized altogether and linked and controlled using associative files as a database management system. Being hash-file oriented, Pick provides efficiency in data access time. Originally, all data structures in Pick were hash-files (at the lowest level) meaning records are stored as associated couplets of a primary key to a set of values. Today a Pick system can also natively access host files in Windows or Unix in any format.
A Pick database is divided into one or more accounts, master dictionaries, dictionaries, files and sub-files, each of which is a hash-table oriented file. These files contain records made up of fields, sub-fields and sub-sub-fields. In Pick, records are called items, fields are called attributes, and sub-fields are called values or sub-values (hence the present-day label "multivalued database"). All elements are variable-length, with field and values marked off by special delimiters, so that any file, record, or field may contain any number of entries of the lower level of entity. As a result, a Pick item (record) can be one complete entity (one entire invoice, purchase order, sales order, etc.), or is like a file on most conventional systems. Entities that are stored as 'files' in other common-place systems (i.e. source programs and text documents) must be stored as records within files on Pick.
The file hierarchy is roughly equivalent to the common Unix-like hierarchy of directories, sub-directories, and files. The master dictionary is similar to a directory in that it stores pointers to other dictionaries, files and executable programs. The master dictionary also contain the command-line language.
All files (accounts, dictionaries, files, sub-files) are organized identically as are all records. This uniformity is exploited throughout the system, both by system functions, and by the system administration commands. For example, the 'find' command will find and report the occurrence of a word or phrase in a file, and can operate on any account, dictionary, file or sub-file.
Each record must have a unique, primary key which determines where in a file that record is stored. To retrieve a record, its key is hashed and the resultant value specifies which of a set of discrete "buckets" (called "groups") to look in for the record. (Within a bucket, records are scanned sequentially.) Therefore, most records (i.e. a complete document) can be read-up using one single disk-read operation. This same method is used to write the record back to its correct "bucket".
In its initial implementation, Pick records were limited to 32K bytes in total (when a 10MB hard disk cost US$5000), although this limit was removed in the 1980s. Files can retain an unlimited number of records, but retrieval efficiency is determined by the number of records relative to the number of buckets allocated to the file. Each file may be initially allocated as many buckets as required, although changing this extent later may (for some filetypes) require the file to be quiescent. All modern multi-value databases have a special file-type which changes extent dynamically as the file is used. These use a technique called linear hashing, whose cost is proportional to the change in file size, not (as in typical hashed files) the file size itself. All files start as a contiguous group of disk pages, and grow by linking additional "overflow" pages from unused disk space.
Initial Pick implementations had no index structures as they were not deemed necessary. Around 1990, a B-tree indexing feature was added. This feature makes secondary key look-ups operate much like keyed inquiries of any other database system: requiring at least two disk reads (a key read then a data-record read).
Files include a "dictionary" fork, and the items in the dictionary fork serve as definitions for the names and structure of the items in the data fork. The dictionary is optional, the system does not use the contents of the dictionary to ensure the integrity of the file as some other DBMS file-systems do; rather it is used only for the reporting tool. A Pick database has no data typing since all data is stored as characters, including numbers (which are stored as character decimal digits). Data integrity, rather than being controlled by the system, is controlled by the applications and the discipline of the programmers. But, because a logical document in Pick is not fragmented (as it would be in SQL) intra-record integrity is automatic.
In contrast to many SQL database systems, Pick allows for multiple, pre-computed field aliases. For example, a date field may have an alias definition for the format 12 Oct 1999, and another alias formatting that same date field like 10/12/99. File cross-connects or joins are handled as a synonym definition of the foreign key. A customer's data, such as name and address, are 'joined' from the customer file into the invoice file via a synonym definition of customer number in the invoice dictionary.
Pick record structure favors a "denormalized" decomposition, where all of the data for an entity is stored in a single record, obviating the need to perform joins. Managing large, sparse data sets in this way can result in efficient use of storage space.
Pick was originally implemented as the Generalized Information Retrieval Language System (GIRLS) on an IBM System/360 in 1965 by Don Nelson and Dick Pick at TRW for use by the U.S. Army to control the inventory of Cheyenne helicopter parts. Pick was subsequently commercially released in 1973 by Microdata Corporation (and their British distributor CMC) as the Reality Operating System now supplied by Northgate Information Solutions.
Originally on the Microdata implementation, and subsequently implemented on all Pick systems, a BASIC-like language called Data/BASIC with numerous syntax extensions for smart terminal interface and database operations was the primary programming language for applications. A PROC procedure language was provided for executing scripts. A SQL-style language called ENGLISH allowed database retrieval and reporting, but not updates (although later, the English command "REFORMAT" allowed updates on a batch basis). ENGLISH did not fully allow manipulating the 3-dimensional multivalued structure of data records. Nor did it directly provide common relational capabilities such as joins. This was because powerful data dictionary redefinitions for a field allowed joins via the execution of a calculated lookup in another file. The system included a spooler. A simple text editor for file-system records was provided, but the editor was only suitable for system maintenance, and could not lock records, so most applications were written with the other tools such as Batch, RPL, or the BASIC language so as to ensure data validation and allow record locking.
Dick Pick founded Pick & Associates, later renamed Pick Systems, then Raining Data and as of 2011[update] TigerLogic. He licensed "Pick" to a large variety of manufacturers and vendors who have produced different "flavors" of Pick. The database flavors sold by TigerLogic is now known as D3, mvBase, and mvEnterprise. Those previously sold by IBM under the "U2" umbrella are known as UniData and UniVerse. Rocket Software purchased IBM's U2 line in 2010.
Dick Pick died of stroke complications in October 1994.
Pick Systems often became tangled in licensing litigation, and devoted relatively little effort to marketing and improving its software. Subsequent ports of Pick to other platforms generally offered the same tools and capabilities for many years, usually with relatively minor improvements and simply renamed (for example, Data/BASIC became Pick/BASIC and ENGLISH became ACCESS). Licensees often developed proprietary variations and enhancements (for example, Microdata created their own input processor called ScreenPro).
What most characterizes Pick is the design and features of the database and the associated retrieval language. The Pick database was licensed to roughly three dozen licensees between 1978 and 1984, some of which are included in this list. Application-compatible implementations evolved into derivatives and also inspired similar systems, of which a few examples are:
Ultimate took this concept further with the DEC LSI/11 family of products by implementing a co-processor in hardware (bit-slice, firmware driven). Instead of a single processor with a WCS microcode enhanced instruction set this configuration used two independent but cooperating CPU's. The LSI11 CPU executed the monitor functions and the co-processor executed the Pick assembler instruction set. The efficiencies of this approach resulted in a 2X performance improvement.
The co-processor concept was used again to create a 5X, 7x and dual-7x versions for Honeywell Level 6 systems. Dual ported memory with private busses to the co-processors were used to increase performance of the LSI11 and Level 6 systems.
Another version used a DEC LSI-11 for the IOP and a 7X board. Ultimate enjoyed moderate success during the 1980s, and even included an implementation running as a layer on top of DEC VAX systems, the 750, 780, 785 and later the MicroVAX. Ultimate also had versions of the Ultimate Operating System running on IBM 370 series systems (under VM and native) and also the 9370 series computers. Ultimate was renamed Allerion, Inc., before liquidation of its assets. Most assets were acquired by Groupe Bull, and consisted of mostly maintaining extant hardware. Bull had its own problems and in approximately 1994 the US maintenance operation was sold to Wang.
Through the implementations above, and others, Pick-like systems became available as database/programming/emulation environments running under many variants of Unix and Microsoft Windows.
Over the years, many important and widely used applications have been written using Pick or one of the derivative implementations. In general, the end users of these applications are unaware of the underlying Pick implementation.
The Pick OS invites comparison with MUMPS, which evolved into Caché. Similarities include:
Content relating to dates before 1987 being verified against paper.[4]
