The KERNAL is Commodore's name for the ROM-resident operating system core in its 8-bit home computers; from the original PET of 1977, via the extended, but strongly related, versions used in its successors; the VIC-20, C64, Plus/4, C16, and C128. The Commodore 8-bit machines' KERNAL consisted of the low-level, close to the hardware, OS routines (in contrast to the BASIC interpreter routines, also located in ROM), and was user callable via a jump table whose central (oldest) part, for reasons of backwards compatibility, remained largely identical throughout the whole 8-bit series. The Kernal rom occupies the last 8K of the 8-bit CPUs 64K address space (X'F000'-X'FFFF'). Commodore is the commonly used name for Commodore International, a West Chester, Pennsylvania based electronics company who was a vital player in the home/personal computer field in the 1980s. ... Read-only memory (ROM) is used as a storage medium in computers. ... In computing, an operating system (aka, OS) is the system software responsible for the direct control and management of hardware and basic system operations. ... 8-bit refers to the number of bits used in the data bus of a computer. ... TRS-80 Color Computer II The home computer is a consumer-friendly word for the second generation of microcomputers (the technical term that was previously used), entering the market in 1977 and becoming common during the 1980s. ... The PET (Personal Electronic Transactor) was a home-/personal computer produced by Commodore starting in the late 1970s. ... For the album by Ash, see 1977 (album). ... Commodore BASIC is the dialect of BASIC used in Commodore Internationals 8-bit home computer line, stretching from the PET of 1977 to the C128 of 1985. ... In computer science, a jump table is a list of the addresses of a set of routines which can be selected by number. ...

Example of use

A simple, still characteristic, example of applying the KERNAL is given by the following 6502 assembly language subroutine (written in ca65 assembler format/syntax): The MOS Technology 6502 is an 8-bit microprocessor designed by MOS Technology in 1975. ... Assembly language commonly called assembly or asm, is a human-readable notation for the machine language that a specific computer architecture uses. ...

 MSG: .ASCIIZ "Hello, world!" LDX #$F3 ; store length of string as two's complement value in x register @LP: LDA MSG-$F3,X ; load character JSR $FFD2 ; call CHROUT in order to output char to current output device (e.g., screen) INX ; next character BNE @LP ; loop back to load new char until whole string done, and then ... RTS ; ... return from the subroutine 

This code stub employs the CHROUT routine, found at address $FFD2 (65490), to send a text string to the default output device (e.g., the display screen). A hello world program is a computer program that prints out Hello, world! on a display device. ... In mathematics and computer science, hexadecimal, or simply hex, is a numeral system with a radix or base of 16 usually written using the symbols 0–9 and A–F or a–f. ...

Acronym or misspelling?

According to early Commodore 'myth' and reported by writer/programmer Jim Butterfield among others, the word KERNAL is an acronym (or maybe more likely, a backronym) standing for Keyboard Entry Read, Network, And Link, which in fact makes good sense considering its role. There's also, however, a theory that the word originated as a misspelling of the word "kernel"^[1] by some unknown Commodore employee. Misspelling or not, Berkeley Softworks later used it when naming the core routines of its GUI OS for 8-bit home computers: the GEOS KERNAL. Jim Butterfield is a Toronto-based author and computer programmer famous for his work with Commodore microcomputers. ... A backronym or bacronym is a type of acronym that is formed to match the letters of a word already in use. ... In computer engineering the kernel is the core of an operating system. ... GEOS (Graphic Environment Operating System) was an operating system from Berkeley Softworks (later Geoworks). ...

The (completely different) OS core in the 16/32-bit Commodore Amiga series was called the Amiga ROM Kernel, i.e. using the correct spelling of kernel. The Amiga is a family of home/personal computers originally developed by Amiga Corporation as an advanced game console. ... AmigaOS is the default native operating system of the Amiga and AmigaOne personal computers. ...

Notes

1. ^ The kernel is the most fundamental part of a program, typically an operating system, that resides in memory at all times and provides the basic services. It is the part of the operating system that is closest to the machine and may activate the hardware directly or interface to another software layer that drives the hardware