Pick Terminology and Concepts

The Pick System uses terms to define itself that are unique in the data processing world. Most of these terms are defined the first time they are mentioned, and a glossary of these and other Pick terms is found among the appendices.
ACCOUNTS AND FILES

Accounts are collections of logically related files, much like departments within a company. Each department has its own set of file cabinets. The name of the account is entered at the "LOGON PLEASE:" message to gain access to the system.

Files are collections of logically related items, much as a file cabinet contains file folders made up of similar types of information. For example, one file cabinet may hold file folders which contain information about your customers, while another cabinet may hold the folders for your suppliers. In the Pick System, the number of items that may be put into a file is only limited by the capacity of the disk.

PICK/BASIC programs, each of which is considered an item, are stored in a file commonly called BP. Note that BP (short for "Basic Programs") is used as a convention only; as with all files, the filename is free-form.

The Pick System gains much of its elegance from the fact that it has only one file structure available. It is known as a random access file structure because records physically reside in the file in random order. The Pick System is excellent for developing on-line, interactive application systems, since accessing data from files is very fast and independent of the size of the file.

An item is a collection of logically related attributes or fields. (Other computer systems typically call this a "record. ") For example, an item in the CUSTOMER-FILE might contain the name and address for a customer. All the items in the same file are typically formatted in a similar manner. For example, the first attribute in each item might be the customer's name, the second attribute might be the address, and so on.

The method by which Pick manages items is unique. Quite simply, any item in the Pick System is a collection, or string, of characters. Pick uses the ASCII1 coding scheme for representing characters. This character set represents 256 unique characters. Since the upper- and lowercase alphabet, numbers, punctuation, and control characters barely use up the first 128 characters, there are plenty of unused characters available for other purposes. Recognizing this fact, the Pick System uses the last four positions in the ASCII coding scheme, numbered 252 through 255, as special characters to be used by the file system. (Computers generally begin counting at zero, which explains why the last four characters are 252 through 255, rather than 253 through 256.)

Since the Pick System treats each item as a string of characters, there is no concept of "type" of fields. Other systems store data differently depending on the type of the data. The primary "types" of data on other systems are numeric (binary, floating-point decimal, Comp-l, Comp-3, packed decimal, etc.) and character fields, used for storing names and other string-type data.
Item-IDs