Apple Pascal
Encyclopedia
Apple Pascal was a language and operating system based on the UCSD Pascal
system.
Apple Pascal refers to an operating system
for the Apple II
family of computers released in August 1979 between the Apple DOS
3.2 and 3.3 versions. The system was included as part of a software/hardware package adding support for the Pascal
language to the Apple II. It added a number of features that would later be incorporated into the 3.3 version, as well as others that would not be seen again until the introduction of ProDOS
.
The biggest changes were to the disk format and file storage methods, as Apple Pascal was designed to take advantage of 140K
5.25" floppy disks. Instead of dividing the disk into 256-byte sectors as with DOS 3.2, Apple Pascal divided it into "blocks" of 512 bytes each, each block thus contained two sectors. This made for a different method for saving and retrieving files. Under Apple DOS, files were saved to any available sector that the OS could find, regardless of location. This caused larger files to become fragmented and slowed down access to the disk when loading and saving. Apple Pascal attempted to rectify this by saving only to consecutive blocks on the disk.
Drawbacks included the new limitations on the naming of files. While Apple DOS allowed filenames up to thirty characters long and any ASCII
character could be used, Apple Pascal dropped the length to fifteen characters and allowed only letters, numbers and periods to be used. This was done to create a cleaner look to the disk's catalog, or file listing, as shorter filenames would minimize the "wrap-around"
on the screen. As most Apple displays at the time were only 40 characters wide, the filename limitations were not seen as that great a drawback.
The consecutive file saving method also created some problems. Deleted filespace could not be used if it was not at the "end" of the disk (after the most recently-saved file). A utility called Krunch was included in the package to "clean up" the disk by moving files until they were all consecutively stored again.
The advantages though, were significant, aside from just the increase in disk access speed. Apple Pascal increased the number of supported file types from the original eight by introducing a two-byte code to indicate type. A timestamp feature was also added, indicating the date and time of a file's creation or last modification. This data would then be shown on a line with the filename by the CATalog command. Previously only a file's name, basic type, and size would be shown. Strangely enough, the timestamp feature was not made a part of the later DOS 3.3.
Disks could also be named for the first time. Under Apple DOS, disks could only be given a volume number, but Apple Pascal disk volume names could be up to seven characters in length.
The Apple Pascal software package also included disk maintenance utilities, the Pascal compiler (set to the UCSD
standard), and a decently-featured assembler to complement the Apple II's built-in "monitor" assembler.
The biggest problem with the Apple Pascal system was that the operating system was too big to fit on one floppy disk. This meant that on a system with only floppy disk drive, constant swapping of disks was needed in order to do anything. A system needed at least two and preferably three drives in order to use the operating system properly.
UCSD Pascal
UCSD Pascal was a Pascal programming language system that ran on the UCSD p-System, a portable, highly machine-independent operating system. UCSD Pascal was first released in 1978...
system.
Apple Pascal refers to an operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
for the Apple II
Apple II
The Apple II is an 8-bit home computer, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer and introduced in 1977...
family of computers released in August 1979 between the Apple DOS
Apple DOS
Apple DOS refers to operating systems for the Apple II series of microcomputers from late 1978 through early 1983. Apple DOS had three major releases: DOS 3.1, DOS 3.2, and DOS 3.3; each one of these three releases was followed by a second, minor "bug-fix" release, but only in the case of Apple DOS...
3.2 and 3.3 versions. The system was included as part of a software/hardware package adding support for the Pascal
Pascal (programming language)
Pascal is an influential imperative and procedural programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.A derivative known as Object Pascal...
language to the Apple II. It added a number of features that would later be incorporated into the 3.3 version, as well as others that would not be seen again until the introduction of ProDOS
ProDOS
ProDOS was the name of two similar operating systems for the Apple II series of personal computers. The original ProDOS, renamed ProDOS 8 in version 1.2, was the last official operating system usable by all Apple II series computers, and was distributed from 1983 to 1993...
.
The biggest changes were to the disk format and file storage methods, as Apple Pascal was designed to take advantage of 140K
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
5.25" floppy disks. Instead of dividing the disk into 256-byte sectors as with DOS 3.2, Apple Pascal divided it into "blocks" of 512 bytes each, each block thus contained two sectors. This made for a different method for saving and retrieving files. Under Apple DOS, files were saved to any available sector that the OS could find, regardless of location. This caused larger files to become fragmented and slowed down access to the disk when loading and saving. Apple Pascal attempted to rectify this by saving only to consecutive blocks on the disk.
Drawbacks included the new limitations on the naming of files. While Apple DOS allowed filenames up to thirty characters long and any ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
character could be used, Apple Pascal dropped the length to fifteen characters and allowed only letters, numbers and periods to be used. This was done to create a cleaner look to the disk's catalog, or file listing, as shorter filenames would minimize the "wrap-around"
Word wrap
In text display, line wrap is the feature of continuing on a new line when a line is full, such that each line fits in the viewable window, allowing text to be read from top to bottom without any horizontal scrolling....
on the screen. As most Apple displays at the time were only 40 characters wide, the filename limitations were not seen as that great a drawback.
The consecutive file saving method also created some problems. Deleted filespace could not be used if it was not at the "end" of the disk (after the most recently-saved file). A utility called Krunch was included in the package to "clean up" the disk by moving files until they were all consecutively stored again.
The advantages though, were significant, aside from just the increase in disk access speed. Apple Pascal increased the number of supported file types from the original eight by introducing a two-byte code to indicate type. A timestamp feature was also added, indicating the date and time of a file's creation or last modification. This data would then be shown on a line with the filename by the CATalog command. Previously only a file's name, basic type, and size would be shown. Strangely enough, the timestamp feature was not made a part of the later DOS 3.3.
Disks could also be named for the first time. Under Apple DOS, disks could only be given a volume number, but Apple Pascal disk volume names could be up to seven characters in length.
The Apple Pascal software package also included disk maintenance utilities, the Pascal compiler (set to the UCSD
UCSD Pascal
UCSD Pascal was a Pascal programming language system that ran on the UCSD p-System, a portable, highly machine-independent operating system. UCSD Pascal was first released in 1978...
standard), and a decently-featured assembler to complement the Apple II's built-in "monitor" assembler.
The biggest problem with the Apple Pascal system was that the operating system was too big to fit on one floppy disk. This meant that on a system with only floppy disk drive, constant swapping of disks was needed in order to do anything. A system needed at least two and preferably three drives in order to use the operating system properly.