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High-level language computer architecture
A high-level language computer architecture (HLLCA) is a computer architecture designed to be targeted by a specific high-level programming language (HLL), rather than the architecture being dictated by hardware considerations. It is accordingly also termed language-directed computer design, coined in McKeeman (1967) and primarily used in the 1960s and 1970s. HLLCAs were popular in the 1960s and 1970s, but largely disappeared in the 1980s. This followed the dramatic failure of the Intel 432 (1981) and the emergence of optimizing compilers and reduced instruction set computer (RISC) architectures and RISC-like complex instruction set computer (CISC) architectures, and the later development of just-in-time compilation (JIT) for HLLs. A detailed survey and critique can be found in Ditzel & Patterson (1980).
HLLCAs date almost to the beginning of HLLs, in the Burroughs large systems (1961), which were designed for ALGOL 60 (1960), one of the first HLLs. The best known HLLCAs may be the Lisp machines of the 1970s and 1980s, for the language Lisp (1959). At present the most popular HLLCAs are Java processors, for the language Java (1995), and these are a qualified success, being used for certain applications. A recent architecture in this vein is the Heterogeneous System Architecture (2012), which HSA Intermediate Layer (HSAIL) provides instruction set support for HLL features such as exceptions and virtual functions; this uses JIT to ensure performance.
There are a wide variety of systems under this heading. The most extreme example is a Directly Executed Language (DEL), where the instruction set architecture (ISA) of the computer equals the instructions of the HLL, and the source code is directly executable with minimal processing. In extreme cases, the only compiling needed is tokenizing the source code and feeding the tokens directly to the processor; this is found in stack-oriented programming languages running on a stack machine. For more conventional languages, the HLL statements are grouped into instruction + arguments, and infix order is transformed to prefix or postfix order. DELs are typically only hypothetical, though they were advocated in the 1970s.
In less extreme examples, the source code is first parsed to bytecode, which is then the machine code that is passed to the processor. In these cases, the system typically lacks an assembler, as the compiler is deemed sufficient, though in some cases (such as Java), assemblers are used to produce legal bytecode which would not be output by the compiler. This approach was found in the Pascal MicroEngine (1979), and is currently used by Java processors.
More loosely, a HLLCA may simply be a general-purpose computer architecture with some features specifically to support a given HLL or several HLLs. This was found in Lisp machines from the 1970s onward, which augmented general-purpose processors with operations specifically designed to support Lisp.
The Burroughs Large Systems (1961) were the first HLLCA, designed to support ALGOL (1959), one of the earliest HLLs. This was referred to at the time as "language-directed design." The Burroughs Medium Systems (1966) were designed to support COBOL for business applications. The Burroughs Small Systems (mid-1970s, designed from late 1960s) were designed to support multiple HLLs by a writable control store. These were all mainframes.
The Wang 2200 (1973) series were designed with a BASIC interpreter in micro-code.
The Pascal MicroEngine (1979) was designed for the UCSD Pascal form of Pascal, and used p-code (Pascal compiler bytecode) as its machine code. This was influential on the later development of Java and Java machines.
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High-level language computer architecture AI simulator
(@High-level language computer architecture_simulator)
High-level language computer architecture
A high-level language computer architecture (HLLCA) is a computer architecture designed to be targeted by a specific high-level programming language (HLL), rather than the architecture being dictated by hardware considerations. It is accordingly also termed language-directed computer design, coined in McKeeman (1967) and primarily used in the 1960s and 1970s. HLLCAs were popular in the 1960s and 1970s, but largely disappeared in the 1980s. This followed the dramatic failure of the Intel 432 (1981) and the emergence of optimizing compilers and reduced instruction set computer (RISC) architectures and RISC-like complex instruction set computer (CISC) architectures, and the later development of just-in-time compilation (JIT) for HLLs. A detailed survey and critique can be found in Ditzel & Patterson (1980).
HLLCAs date almost to the beginning of HLLs, in the Burroughs large systems (1961), which were designed for ALGOL 60 (1960), one of the first HLLs. The best known HLLCAs may be the Lisp machines of the 1970s and 1980s, for the language Lisp (1959). At present the most popular HLLCAs are Java processors, for the language Java (1995), and these are a qualified success, being used for certain applications. A recent architecture in this vein is the Heterogeneous System Architecture (2012), which HSA Intermediate Layer (HSAIL) provides instruction set support for HLL features such as exceptions and virtual functions; this uses JIT to ensure performance.
There are a wide variety of systems under this heading. The most extreme example is a Directly Executed Language (DEL), where the instruction set architecture (ISA) of the computer equals the instructions of the HLL, and the source code is directly executable with minimal processing. In extreme cases, the only compiling needed is tokenizing the source code and feeding the tokens directly to the processor; this is found in stack-oriented programming languages running on a stack machine. For more conventional languages, the HLL statements are grouped into instruction + arguments, and infix order is transformed to prefix or postfix order. DELs are typically only hypothetical, though they were advocated in the 1970s.
In less extreme examples, the source code is first parsed to bytecode, which is then the machine code that is passed to the processor. In these cases, the system typically lacks an assembler, as the compiler is deemed sufficient, though in some cases (such as Java), assemblers are used to produce legal bytecode which would not be output by the compiler. This approach was found in the Pascal MicroEngine (1979), and is currently used by Java processors.
More loosely, a HLLCA may simply be a general-purpose computer architecture with some features specifically to support a given HLL or several HLLs. This was found in Lisp machines from the 1970s onward, which augmented general-purpose processors with operations specifically designed to support Lisp.
The Burroughs Large Systems (1961) were the first HLLCA, designed to support ALGOL (1959), one of the earliest HLLs. This was referred to at the time as "language-directed design." The Burroughs Medium Systems (1966) were designed to support COBOL for business applications. The Burroughs Small Systems (mid-1970s, designed from late 1960s) were designed to support multiple HLLs by a writable control store. These were all mainframes.
The Wang 2200 (1973) series were designed with a BASIC interpreter in micro-code.
The Pascal MicroEngine (1979) was designed for the UCSD Pascal form of Pascal, and used p-code (Pascal compiler bytecode) as its machine code. This was influential on the later development of Java and Java machines.