The Symbolic Optimal Assembly Program (SOAP) is an assembler for the IBM 650 Magnetic Drum Data-Processing Machine, an early computer first used in 1954. It was developed by Stan Poley at the IBM Thomas J. Watson Research Center. [1] SOAP is called "Optimal" (or "Optimum") because it attempts to store generated instructions on the storage drum to minimize the access time from one instruction to the next. SOAP is a multi-pass assembler, that is, it processes the source program more than once in order to generate the object program.
The first version of SOAP was succeeded by SOAP II in 1957, [2] which supported additional hardware features such as index registers and magnetic core memory, then SOAP IIA in 1958, [3] SOAP 2L, SOAP 2L Tape, SOAP 4000, and SOAP 42 in 1961. [4] SOAP was used as a backend to the FOR TRANSIT compiler in 1957. [1]
Donald Knuth independently produced versions named SOAP III in 1958 [5] and SUPERSOAP in 1959 [6] at Case Institute of Technology, now part of Case Western Reserve University in Cleveland, Ohio. The US National Bureau of Standards, under the direction of Herbert Howe, also wrote a version of SOAP, called ISOPAR, said to significantly improve optimization. [7]
The IBM 650 uses a magnetic drum as main storage. The drum holds up to 4,000 words and rotates at 12,500 revolutions per minute (RPM), 4.8 msec per rotation, or average access time of 2.4 msec. "If you placed your instructions sequentially onto the drum, you would have to wait for a complete rotation of the drum before the CPU could obtain the next instruction. Since many instructions on the 650 could execute in around 3 milliseconds, you would try to optimize your code by placing the instructions on the drum in such a way that it would not take the drum a full revolution to access your next instruction." [8] Each instruction contains the address of the next instruction to execute; instead of a sequential array of instructions the memory appears to be a linked list. SOAP optimizes by placing instructions to be executed sequentially in locations around the drum such that the next instruction is available as soon as possible after the current instruction finishes. This optimization was said to make the assembled programs "run as much as six or seven times faster." [1]
SOAP II supports the following pseudo-operations (assembly directives): [2]
OP | Name | Description |
---|---|---|
HED | Heading | Separates programs, possibly written separately, which are being assembled together. It can specify a character to be appended to symbol names in this section to avoid naming conflicts. |
REL | Relocatable Library Program | Defines the start of a relocatable library program being assembled ahead of the main program. It specifies the amounts by which assembled addresses should be relocated. |
RBR | Relocatable Block Reservation | Reserves a range of drum locations as "erasable blocks within the routine," to avoid using a number of cards to specify a data area. |
REQ | Relocatable Equivalence | Equates a symbol to the address of a relocatable subroutine, and optionally specifies a relocation amount. |
BLR | Block Reservation | Marks a range of drum addresses as unavailable for assignment by SOAP. |
BLA | Block Availability | Marks a range of drum addresses as available for assignment. |
REG | Regional Specification | Defines a range of drum addresses as a "region", identified by a one-character region id. Locations within the region are specified as <region id>nnnn where nnnn is a number from 1 to the number of locations specified for the region. |
ALF | Alphabetic Data | Specifies up to five alphabetic characters to be assembled at the specified location. |
PAT | Punch Assembly Table | Tells SOAP to punch a deck of fifty Type Y cards listing used and available drum locations at any point during assembly. This table can be examined manually and fed back into SOAP on a subsequent assembly to restore "the availability status which existed at some point of a prior assembly." |
BOP | Beginning of Program | Indicates the start of a new program to be assembled separately from previous programs in the same card deck. |
EQU | Equivalence | Equates a symbol to an absolute, regional, or symbolic value. |
SYN | Synonym | Equates a symbol to an absolute drum address. The address is marked unavailable for assignment |
Each source card can contain up to ten characters of comments in columns 63–72. For longer comments, up to thirty characters may be entered on a Comments Card (Type 1, '1' in column 41) in columns 43–72
In computer programming, assembly language, often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported.
In computing, a linker or link editor is a computer system program that takes one or more object files and combines them into a single executable file, library file, or another "object" file.
Random access is the ability to access an arbitrary element of a sequence in equal time or any datum from a population of addressable elements roughly as easily and efficiently as any other, no matter how many elements may be in the set. In computer science it is typically contrasted to sequential access which requires data to be retrieved in the order it was stored.
The IBM 650 Magnetic Drum Data-Processing Machine is an early digital computer produced by IBM in the mid-1950s. It was the first mass-produced computer in the world. Almost 2,000 systems were produced, the last in 1962, and it was the first computer to make a meaningful profit. The first one was installed in late 1954 and it was the most popular computer of the 1950s.
Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory.
In computer science, program optimization, code optimization, or software optimization is the process of modifying a software system to make some aspect of it work more efficiently or use fewer resources. In general, a computer program may be optimized so that it executes more rapidly, or to make it capable of operating with less memory storage or other resources, or draw less power.
The IBM 1130 Computing System, introduced in 1965, was IBM's least expensive computer at that time. A binary 16-bit machine, it was marketed to price-sensitive, computing-intensive technical markets, like education and engineering, succeeding the decimal IBM 1620 in that market segment. Typical installations included a 1 megabyte disk drive that stored the operating system, compilers and object programs, with program source generated and maintained on punched cards. Fortran was the most common programming language used, but several others, including APL, were available.
Addressing modes are an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing modes that are defined in a given instruction set architecture define how the machine language instructions in that architecture identify the operand(s) of each instruction. An addressing mode specifies how to calculate the effective memory address of an operand by using information held in registers and/or constants contained within a machine instruction or elsewhere.
The IBM 305 RAMAC was the first commercial computer that used a moving-head hard disk drive for secondary storage. The system was publicly announced on September 14, 1956, with test units already installed at the U.S. Navy and at private corporations. RAMAC stood for "Random Access Method of Accounting and Control", as its design was motivated by the need for real-time accounting in business.
The DEUCE was one of the earliest British commercially available computers, built by English Electric from 1955. It was the production version of the Pilot ACE, itself a cut-down version of Alan Turing's ACE.
The Bendix G-15 is a computer introduced in 1956 by the Bendix Corporation, Computer Division, Los Angeles, California. It is about 5 by 3 by 3 feet and weighs about 966 pounds (438 kg). The G-15 has a drum memory of 2,160 29-bit words, along with 20 words used for special purposes and rapid-access storage. The base system, without peripherals, cost $49,500. A working model cost around $60,000. It could also be rented for $1,485 per month. It was meant for scientific and industrial markets. The series was gradually discontinued when Control Data Corporation took over the Bendix computer division in 1963.
Autocoder is any of a group of assemblers for a number of IBM computers of the 1950s and 1960s. The first Autocoders appear to have been the earliest assemblers to provide a macro facility.
In the history of computing, optimum programming, or optimum coding is the practice of arranging a computer program's instructions in memory so as to minimize the time the machine spends waiting for instructions. It is of historical interest mainly due to the design of many early digital computers.
An instruction set simulator (ISS) is a simulation model, usually coded in a high-level programming language, which mimics the behavior of a mainframe or microprocessor by "reading" instructions and maintaining internal variables which represent the processor's registers.
The IBM Basic assembly language and successors is a series of assembly languages and assemblers made for the IBM System/360 mainframe system and its successors through the IBM Z.
In computing, a compiler is a computer program that transforms source code written in a programming language or computer language, into another computer language. The most common reason for transforming source code is to create an executable program.
Control tables are tables that control the control flow or play a major part in program control. There are no rigid rules about the structure or content of a control table—its qualifying attribute is its ability to direct control flow in some way through "execution" by a processor or interpreter. The design of such tables is sometimes referred to as table-driven design. In some cases, control tables can be specific implementations of finite-state-machine-based automata-based programming. If there are several hierarchical levels of control table they may behave in a manner equivalent to UML state machines
A hot spot in computer science is most usually defined as a region of a computer program where a high proportion of executed instructions occur or where most time is spent during the program's execution.
FOR TRANSIT is a subset of the FORTRAN programming language for the IBM 650 Magnetic Drum Data-Processing Machine, developed by a group led by Bob Bemer. FORTRAN, the first high-level programming language, was developed for the IBM 704 in 1957, at the same time IBM wanted to provide something similar for customers of the older, less powerful, but popular 650—eventually over 2000 650s were sold.
The Gamma 3 was an early electronic vacuum-tube computer. It was designed by Compagnie des Machines Bull in Paris, France and released in 1952.