The IBM 700/7000 series is a series of large-scale (mainframe) computer systems that were made by IBM through the 1950s and early 1960s. The series includes several different, incompatible processor architectures. The 700s use vacuum-tube logic and were made obsolete by the introduction of the transistorized 7000s. The 7000s, in turn, were eventually replaced with System/360, which was announced in 1964. However the 360/65, the first 360 powerful enough to replace 7000s, did not become available until November 1965. Early problems with OS/360 and the high cost of converting software kept many 7000s in service for years afterward.
The 700 class machines use vacuum tubes; the 7000 class machines are transistorized. All machines (like most other computers of the time) use magnetic-core memory; except for early 701 and 702 models, which initially used Williams tube CRT memory and were later converted to magnetic-core memory.
Software compatibility issues
Early computers were sold without software. As operating systems began to emerge, having four different mainframe architectures plus the IBM 1400 midline architectures became a major problem for IBM since it meant at least four different programming efforts were required.
The System/360 combines the best features of the 7000 and 1400 series architectures into a single design both for commercial computing and for scientific and engineering computing. However, its architecture is not compatible with those of the 7000 and 1400 series, so some 360 models have optional features that allow them to emulate the 1400 and 7000 instruction sets in microcode. One of the selling points of the System/370, the successor of the 360 introduced in mid-1970, was improved 1400/7000 series emulation, which could be done under operating system control rather than shutting down and restarting in emulation mode as was required for emulation of 7040/44, 7070/72/74, 7080 and 7090/94 on all of the 360s except the 360/85.
Peripherals
While the architectures differ, the machines in the same class use the same electronics technologies and generally use the same peripherals. Tape drives generally[lower-alpha 1] use 7-track format, with the IBM 727 for vacuum tube machines and the 729 for transistor machines. Both the vacuum tube and most transistor models use the same card readers, card punches, and line printers that were introduced with the 701. These units, the IBM 711, 721, and 716, are based on IBM accounting machine technology and even include plugboard control panels. They are relatively slow and it was common for 7000 series installations to include an IBM 1401, with its much faster peripherals, to do card-to-tape and tape-to-line-printer operations off-line. Three later machines, the 7010, the 7040 and the 7044, adopted peripherals from the midline IBM 1400 series. Some of the technology for the 7030 was used in data channels and peripheral devices on other 7000 series computers, e.g., 7340 Hypertape.
Known as the Defense Calculator while in development in the IBM Poughkeepsie Laboratory, this machine was formally unveiled April 7, 1953 as the IBM 701 Electronic Data Processing Machine.
To expand the memory from 2048 to 4096 words, a 33rd instruction was added that uses the most-significant bit of its address field to select the bank. (This instruction was probably created using the "No OP" instruction, which appears to have been the only instruction with unused bits, as it originally ignored its address field. However, documentation on this new instruction is not currently available.)
2,048 or 4,096 – 36-bit binary words with six-bit characters
Later scientific architecture (704/709/7090/7094)
IBM 7090's at NASA's Project Mercury, 1962
IBM's 36-bit scientific architecture was used for a variety of computation-intensive applications. First machines were the vacuum-tube 704 and 709, followed by the transistorized 7090, 7094, 7094-II, and the lower-cost 7040 and 7044. The ultimate model was the Direct Coupled System (DCS) consisting of a 7094 linked to a 7044 that handled input and output operations.
Single-precision floating-point numbers have a magnitude sign, an 8-bit excess-128 exponent and a 27-bit magnitude
Double-precision floating-point numbers, introduced on the 7094, have a magnitude sign, a 17-bit excess-65536 exponent, and a 54-bit magnitude
Alphameric characters are 6-bit BCD, packed six to a word.
Instruction format
The basic instruction format is a three-bit prefix, fifteen-bit decrement, three-bit tag, and fifteen-bit address. The prefix field specifies the class of instruction. The decrement field often contains an immediate operand to modify the results of the operation, or is used to further define the instruction type. The three bits of the tag specify three (seven in the 7094) index registers, the contents of which are subtracted from the address to produce an effective address. The address field either contains an address or an immediate operand.
The accumulator (and multiplier-quotient) registers operate in sign/magnitude format. The accumulator has two overflow bits, labelled Q and P. Logical instructions clear or ignore S and Q; the Add and Carry Logical (ACL) instruction does an end-around carry from bit P to bit 35.
The Index registers operate using two's complement format and when used to modify an instruction address are subtracted from the address in the instruction. On machines with three index registers, if the tag has two or three bits set (i.e. selected multiple registers) then their values are ORed together before being subtracted. The IBM 7094, with seven index registers, powers up in multiple tag mode for compatibility with earlier machines, so that programs that used this trick could continue to be used; the Leave Multiple Tag Mode (LMTM) instruction turns that mode off, so that the tag specifies which of the index registers to use, and the Enter Multiple Tag Mode (EMTM) instruction turns it back on.
The Sense Indicators permit interaction with the operator via panel switches and lights.
Memory
704: 4,096 or 8,192 or 32,768 – 36-bit binary words with six-bit characters
709, 7090, 7094, 7094 II, 7040, 7044: 32,768 – 36-bit binary words with six-bit characters
Input/output
The 709/7090 series use Data Synchronizer Channels for high-speed input/output, such as tape and disk. The basic 7-bit[lower-alpha 2] DSCs, e.g., 7607, execute their own simple programs from the computer memory that controls the transfer of data between memory and the I/O devices; the more advanced 9-bit[lower-alpha 3] 7909 supports more sophisticated channel programs. Because the unit record equipment on the 709x was so slow, punched card I/O and high-speed printing were often performed by transferring magnetic tapes to and from an off-line IBM 1401. Later, the data channels were used to connect a 7090 to a 7040 or a 7094 to a 7044 to form the IBM 7094/7044 Direct Coupled System (DCS). In that configuration, the 7044, which could use faster 1400 series peripherals, primarily handled I/O.
FORTRAN assembly program
The FORTRAN Assembly Program (FAP) is an assembler for the 709, 7090, and 7094, originally written at the Western Data Processing Center by David E. Ferguson and Donald P. Moore for the 709.[1] It runs under IBM's Fortran Monitor System (FMS) and IBSYS operating systems. An earlier assembler was SHARE Compiler-Assembler-Translator (SCAT) under SHARE Operating System (SOS). Macros were added to FAP by Bell Laboratories (BE-FAP), and the final 7090/7094 assembler was Macro Assembly Program (IBMAP), under IBSYS/IBJOB. SCAT, FAP and MAP were mutually incompatible.
Its pseudo-operation BSS, used to reserve memory, is the origin of the common name of the "BSS section", still used in many assembly languages today for designating reserved memory address ranges of the type not having to be saved in the executable image.
Commercial architecture (702/705/7080)
IBM 702IBM 7080
The IBM 702 and IBM 705 are similar, and the 705 can run many 702 programs without modification, but they are not completely compatible.
The IBM 7080 is a transistorized version of the 705, with various improvements. For backward compatibility it can be run in 705 I[2] mode, 705 II[3] mode, 705 III[4] mode, or full 7080 mode.
Data format
Data is represented by a variable-length string of characters terminated by a Record mark.
Instruction format
Five characters: one character opcode and four character address – OAAAA
Registers
702
two Accumulators (A & B) – 512 characters
705
one Accumulator – 256 characters
14 auxiliary storage units – 16 characters
one auxiliary storage unit – 32 characters
7080
one Accumulator – 256 characters
30 auxiliary storage units – 512 characters
32 communication storage units – 8 characters
Memory
702
2,000 to 10,000 characters in Williams tubes (in increments of 2,000 characters)
Character cycle rate – 23 microseconds
705 (models I, II, or III)
20,000 or 40,000 or 80,000 characters of core memory
Character cycle rate – 17 microseconds or 9.8 microseconds
7080
80,000 or 160,000 characters of Core memory
Character cycle rate – 2.18 microseconds
Input/output
The 705 and the basic 7080 use channels with a 7-bit[lower-alpha 2] interface. The 7080 can be equipped with 7908 data channels to attach faster devices using a 9-bit[lower-alpha 3] interface.
1400 series architecture (7010)
IBM 7010 system: console (in front), disc drives and processing modules (left), tape storage, punch card reader and printer (right)
The 700/7000 commercial architecture inspired the very successful IBM 1400 series of mid-sized business computers. In turn, IBM later introduced a mainframe version of the IBM 1410 called the IBM 7010.
Data format
Data is represented by a variable length string of characters terminated by a word mark.
Instruction format
Variable length: 1, 2, 6, 7, 11, or 12 characters.
Registers
Fifteen five-character fields in fixed locations in low memory can be treated as index registers, whose values can be added to the address specified in an instruction. Also, certain internal registers that would today be invisible, such as the addresses of the characters being currently processed, are exposed to the programmer; in particular, the B address register is often used for subroutine linkage.
The IBM 7070, IBM 7072, and IBM 7074 are decimal, fixed-word-length machines. They use a ten-digit word like the smaller and older IBM 650, but are not instruction set compatible with the 650.
The 707x uses channels with a 7-bit[lower-alpha 2] interface. The 7070 and 7074 can be equipped with 7907 data channels to attach faster devices using a 9-bit[lower-alpha 3] interface.
The IBM 7700 Data Acquisition System is not a member of the IBM 7000 series, despite its number and its announcement date of December 2, 1963.
Performance
All of the 700 and 7000 series machines predate standard performance measurement tools such as the Whetstone (1972), Dhrystone (1984), LINPACK (1979), or Livermore loops (1986) benchmarks.
In the table below, the Gibson and Knight measurements report speed, where higher numbers are better; the TRIDIA measurement reports time, where lower numbers are better.
IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the computer market with the 7000 series and the later System/360, followed by the System/370. Current mainframe computers in IBM's line of business computers are developments of the basic design of the System/360.
The IBM 704 is the model name of a large digital mainframe computer introduced by IBM in 1954. It was the first mass-produced computer with hardware for floating-point arithmetic. The IBM 704 Manual of operation states:
The type 704 Electronic Data-Processing Machine is a large-scale, high-speed electronic calculator controlled by an internally stored program of the single address type.
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.
The IBM 7090 is a second-generation transistorized version of the earlier IBM 709 vacuum tube mainframe computer that was designed for "large-scale scientific and technological applications". The 7090 is the fourth member of the IBM 700/7000 series scientific computers. The first 7090 installation was in December 1959. In 1960, a typical system sold for $2.9 million or could be rented for $63,500 a month.
The IBM 7030, also known as Stretch, was IBM's first transistorized supercomputer. It was the fastest computer in the world from 1961 until the first CDC 6600 became operational in 1964.
The IBM 709 is a computer system that was initially announced by IBM in January 1957 and first installed during August 1958. The 709 was an improved version of its predecessor, the IBM 704, and was the third of the IBM 700/7000 series of scientific computers. The improvements included overlapped input/output, indirect addressing, and three "convert" instructions which provided support for decimal arithmetic, leading zero suppression, and several other operations. The 709 had 32,768 words of 36-bit magnetic core memory and could execute 42,000 add or subtract instructions per second. It could multiply two 36-bit integers at a rate of 5000 per second.
An index register in a computer's CPU is a processor register used for pointing to operand addresses during the run of a program. It is useful for stepping through strings and arrays. It can also be used for holding loop iterations and counters. In some architectures it is used for read/writing blocks of memory. Depending on the architecture it may be a dedicated index register or a general-purpose register. Some instruction sets allow more than one index register to be used; in that case additional instruction fields may specify which index registers to use.
In computer architecture, 36-bit integers, memory addresses, or other data units are those that are 36 bits wide. Also, 36-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers, address buses, or data buses of that size. 36-bit computers were popular in the early mainframe computer era from the 1950s through the early 1970s.
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.
IBM 7070 is a decimal-architecture intermediate data-processing system that was introduced by IBM in 1958. It was part of the IBM 700/7000 series, and was based on discrete transistors rather than the vacuum tubes of the 1950s. It was the company's first transistorized stored-program computer.
The IBM 7080 was a variable word length BCD transistor computer in the IBM 700/7000 series commercial architecture line, introduced in August 1961, that provided an upgrade path from the vacuum-tube IBM 705 computer.
A decimal computer is a computer that can represent numbers and addresses in decimal and that provides instructions to operate on those numbers and addresses directly in decimal, without conversion to a pure binary representation. Some also had a variable wordlength, which enabled operations on numbers with a large number of digits.
Input/Output Control System (IOCS) is any of several packages on early IBM entry-level and mainframe computers that provided low level access to records on peripheral equipment. IOCS provides functionality similar to 1960s packages from other vendors, e.g., File Control Processor (FCP) in RCA 3301 Realcom Operating System, GEFRC in GECOS, and to the later Record Management Services (RMS) in DEC VAX/VMS
The IBM 711 was a punched card reader used as a peripheral device for IBM mainframe vacuum tube computers and early transistorized computers. Announced on May 21, 1952, it was first shipped with the IBM 701. Later IBM computers that used it were the IBM 704, the IBM 709, and the transistorized IBM 7090 and 7094.
The IBM System/360 Model 65 is a member of the IBM System/360 family of computers. It was announced April 1965, and replaced two models, the Model 60 and Model 62, announced one year prior but never shipped. It was discontinued in March 1974.
The IBM System/360 Model 85 is a high-end member of the System/360 family of computers, with many advanced features, and was announced in January 1968 and first shipped in December 1969. IBM built only about 30 360/85 systems because of "a recession in progress".
The IBM System/370 Model 165 were jointly announced June 30, 1970 as "designed for ... the Seventies." That same day IBM announced the 370/195. They were the first three models of the IBM System/370 line of computers.
The IBM System/370 Model 168 and Model 158 were both announced on August 2, 1972. Prior 370 systems had not "offered virtual storage capability, which was to be a hallmark of the 370 line," and some said that the 168 and 158 were the first "real 370" products. By contrast, "in 1972, the System/370 Advanced Function was released and had new Address Relocation Hardware and now supported four new operating systems ."
In addition to the drums used as main memory by IBM, e.g., IBM 305, IBM 650, IBM offered drum devices as secondary storage for the 700/7000 series and System/360 series of computers.
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