Small-C is both a subset of the

C programming language ''The C Programming Language'' (sometimes termed ''K&R'', after its authors' initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well as ...

, suitable for resource-limited

microcomputer A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (P ...

s and

embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...

s, and an implementation of that subset. Originally valuable as an early

compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that ...

for microcomputer systems available during the late 1970s and early 1980s, the implementation has also been useful as an example simple enough for teaching purposes. The original compiler, written in Small-C for the

Intel 8080 The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compati ...

by Ron Cain, appeared in the May 1980 issue of '' Dr. Dobb's Journal of Computer Calisthenics & Orthodontia''. James E. Hendrix improved and extended the original compiler, and wrote ''The Small-C Handbook''. Ron

bootstrapped In general, bootstrapping usually refers to a self-starting process that is supposed to continue or grow without external input. Etymology Tall boots may have a tab, loop or handle at the top known as a bootstrap, allowing one to use fingers ...

Small-C on the

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PDP 11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...

/45

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

system with an account provided by John Bass for Small C development. The provided

source code In computing, source code, or simply code, is any collection of code, with or without comment (computer programming), comments, written using a human-readable programming language, usually as plain text. The source code of a Computer program, p ...

was released with management permission into the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

. Small-C was important for tiny computers in a manner somewhat analogous to the importance of GCC for larger computers. Just like its

counterparts, the compiler generates

assembler code In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence be ...

, which then must be translated to

machine code In computer programming, machine code is any low-level programming language, consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Each instruction causes the CPU to perform a ver ...

by an available assembler. Small-C is a retargetable compiler. Porting Small-C requires only that the back-end code generator and the library to operating system interface calls be rewritten for the target processor.

Language subset

"In May of 1980 Dr. Dobb's Journal ran an article entitled "A Small C Compiler for the 8080s" in which Ron Cain presented a small compiler for a subset of the C language. The most interesting feature of the compiler besides its small size was the language in which it was written—the one it compiled. It was a self-compiler! (Although this is commonplace today, it was a fairly novel idea at the time.) With a simple, one-pass algorithm, his compiler generated assembly language for the 8080 processor. Being small, however, it had its limitations. It recognized only characters, integers, and single dimension arrays of either type. The only loop controlling device was the while statement. There were no Boolean operators, so the bitwise logical operators & (AND) and , (OR) were used instead. But even with these limitations, it was a very capable language and a delight to use, especially compared to assembly language. Recognizing the need for improvements, Ron encouraged me to produce a second version, and in December 1982 it also appeared in Dr. Dobb's Journal. The new compiler augmented Small C with (1) code optimizing, (2) data initializing, (3) conditional compiling, (4) the extern storage class, (5) the for, do/while, switch, and goto statements, (6) combination assignment operators, (7) Boolean operators, (8) the one's complement operator, (9) block local variables, and (10) various other features. Then in 1984 Ernest Payne and I developed and published a CP/M compatible run-time library for the compiler. It consisted of over 80 functions and included most of those in the UNIX C Standard I/O Library—the ones that pertained to the CP/M environment. This became version 2.1 and the subject of The Small C Handbook.

References

Notes

* Ron Cain, "A Small C Compiler for the 8080's", '' Dr. Dobb's Journal'', April–May 1980, pp. 5–19 * James E. Hendrix, ''The Small-C Handbook'', Reston 1984, * James E. Hendrix, ''A Small C Compiler: Language, Usage, Theory, and Design'', M & T Books 1988, * James E. Hendrix, ''Small C Compiler'', M & T Books 1990,

External links

Comments by Ron Cain on creation of Small-CNative compiler for the BBC ComputerDr. Dobb's Small-C Resource CDROM iso-image download
{{Authority control C programming language family 1980 software C (programming language) compilers CP/M software

Language subset

See also

Small-C variants

References

Notes

External links