IBM 1130

Developer	IBM Boca Raton
Manufacturer	IBM
Type	minicomputer
Release date	1965 (1965)
Introductory price	~$1,000 per month rental, equivalent to about $9,300 in 2022
Discontinued	early 1980s[1]
Units shipped	10,000 est.[1]
Operating system	Disk Monitor 2 (DM2)
CPU	16-bit, word addressed, 15-bit address space
Memory	magnetic core
Storage	IBM 2310 disk drive
Removable storage	IBM 2515 single disk cartridge
Display	IBM 1627 Calcomp Plotter, IBM 2250, optional
Input	punched card, paper tape, console
Connectivity	IBM Synchronous Communication Adaptor (SCA)
Dimensions	desk-size: width 58.5 in, depth 29 in, height 44.125 in[2]
Mass	660 lb[2]
Marketing target	small engineering companies, schools
Backward compatibility	via Fortran
Predecessor	IBM 1620, IBM 650
Successor	IBM Series/1 IBM System/7
Related	IBM 1800 process control system
Website	ibm1130.org

The IBM 1130 Computing System, introduced in 1965,^[3] 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.

IBM 1130 console

The 1130 was also used as an intelligent front-end for attaching an IBM 2250 Graphics Display Unit, or as remote job entry (RJE) workstation, connected to a System/360 mainframe.

IBM 1130 with peripherals, including paper tape reader punch, IBM 1442 card reader/punch (rear) and IBM 1627 Calcomp plotter.

Description

A double width SLT card from an IBM 1130. The square metal cans contain the hybrid circuits.

The total production run of the 1130 has been estimated at 10,000.^[4] The 1130 holds a place in computing history because it (and its non-IBM clones) gave many people their first direct interaction with a computer. Its price-performance ratio was good and it notably included inexpensive, removable disk storage, with reliable, easy-to-use software that could be in several high-level languages. The low price (from around $32,000 or $41,000 with disk drive)^[3] and well-balanced feature set enabled interactive "open shop" program development.

The IBM 1130 uses the same electronics packaging, called Solid Logic Technology (SLT), used in System/360. It has a 16-bit binary architecture, as do later minicomputers like the PDP-11 and Data General Nova.

The address space is 15 bits, limiting the 1130 to 32,768 16-bit words (65,536 bytes) of memory. The 1130 uses magnetic-core memory, which the processor addresses on word boundaries, using direct, indirect, and indexed addressing modes.

Software

To maximize speed and conserve space, the operating system and compilers are written entirely in assembly language and employ techniques that are rare today, including intermixing code and data as well as self-modifying code.

Much user programming is done in Fortran. The 1130 Fortran compiler can run on a machine with only 4,096 words of core—though the compiled program might not fit on such a machine. In this multi-pass compiler, each "phase" processes the entire source program and takes it another step toward machine code. For example, the first phase reads the source statements into memory, discards comment lines, removes spaces except in text literals, concatenates continuation lines and identifies labels. The compiler is available in a disk-resident version as well as on 8-channel punched paper tape or punched cards.

The most widely used operating system for the 1130 is the Disk Monitor System Version 2 (DM2) introduced in 1967. DM2 is a single-task batch-oriented system. It requires a system with at least 4 KB of core memory and one integrated 2310 disk drive for system residence. The Supervisor is tiny by modern standards, containing assorted system details such as first-level interrupt routines, called Interrupt Level Subroutines, plus the disk driver and routines to load the interpreter of job control commands and the card reader driver. Device drivers for other I/O devices required by a job are incorporated as part of the loading of that job, which might also include the replacement of the basic disk driver by a more advanced driver. During the execution of a job, only a resident monitor, called the Skeleton Supervisor, resides in memory. This Supervisor requires just 1020 bytes, so a task's first available memory starts with address /01FE (hexadecimal) or word 510. When the job ends or is aborted, the supervisor loads the Monitor Control Record Analyzer (MCRA) to read the job control for the next. While the job is running, the Supervisor is inactive. Aside from device drivers and interrupt processing all CPU time is entirely devoted to the job's activities. Other programs distributed as part of the operating system are a core dump utility, DUMP, and the Disk Utility Program, DUP.

A Card/Paper Tape Programming System was available to support systems without disk.

There is a hierarchy of device drivers: those with names ending in Z are for Fortran, such as DISKZ, while assembler programmers might use DISK0, and DISK1 was even faster at reading multiple disk sectors. But DISKZ starts its sector addressing with the first available unused sector, while the others start with sector zero of the disk, making it possible for a programmer unfamiliar with disk organization to inadvertently overwrite the bootstrap loader.

Other programming languages available on the 1130 include

• APL,^[12]
• BASIC,
• COBOL,^{[note 1]}
• FORTH,
• PL/I (in the form of the SL/1 interpreter),^{[note 2]} and
• RPG.^{[note 3]}

There is even a French language ALGOL compiler, in which for example "Debut ...Fin;" take the place of "Begin ... End;". All its messages are in French, so "Bonne compilation" is the goal.

Eastern Michigan University developed a Fortran IV compiler for the 1130, known as Fortran-EMU, as an alternative to the Fortran IV (subset) compiler provided by IBM. It adds many Fortran Iv features not supported by the IBM compiler, including the LOGICAL data type, six-letter variable names, and enhanced diagnostics. The Fortran-EMU compiler was distributed as a deck of punched cards in a disk image file format with all the remaining system area deleted, to prevent copying other modules that would normally reside on the same disk, such as the assembler or compilers.

Oklahoma State University developed an ALGOL 68 compiler, written in ANSI Fortran 1966.^[13][14][15]

A FOCAL interpreter was developed at the University of Michigan.

IBM also distributed a large library of programs, both IBM-supported (Type I and II) and unsupported (Type III and IV).

Since the 1130 was aimed primarily at the scientific market, scientific and engineering programs predominated:

• Scientific Subroutine Package
• Draw and Plot Subroutines
• Electric Power System Load Flow Program
• Multiple Regression
• Calculation of Electrical Distribution System Fault Currents
• Pipe Analysis
• COGO coordinate geometry
• Continuous System Modeling (CSMP)
• Linear Programming Mathematical optimization Subroutine System
• Structural Engineering System Solver (STRESS)
• Statistical System^[16]

The 1130 also occupied a niche as a data processing machine for smaller organizations:

• 1130 Commercial Subroutine Package
• Student Information System
• CPM/PERT

There is also special-purpose software:

• Remote Job Entry (RJE)^[17]
• Typesetting^[18]

Job control

Batch operation of the 1130 is directed by control records in the primary input stream (card or paper tape reader). There are two types of control records, monitor control records and supervisor control records.^[19]

Operating procedure

Punched card containing a self-loading 1130 program that would copy the deck of cards placed after it in the input hopper.

The enduring memories of the IBM 1130 may have resulted from its need for continual human intervention. It was usually occupied running "jobs" specified by a deck of punched cards. The human operator would load jobs into the card reader and separate them back into jobs for return, perhaps along with printed output, to the submitter. The operator would also have to watch the 1130 for evidence of a malfunctioning or stalled job and intervene by pressing the INT REQ key on the keyboard to skip ahead to the start of the next job.^[20]

Marking the start of a job was a punched card that started with // JOB. Any card that started with // was a command to the Supervisor and could not be used as user program or data. Other commands included // DUP to execute the Disk Utility Program (to delete files or add the file in the temporary area to the file collection) and // XEQ to execute a named program from disk. If a user program tried to read a command card, the standard card reader routine would signal end-of-input to the program and save that card's content for the Supervisor.

Initial Program Load (IPL)

Unlike the IBM 360, where a booting device can be selected from the system console, an IBM 1130 can only be "booted" (IPL'd: Initial Program Load) from an external device: a card reader or a paper tape reader.^[21][22]

The bootstrap procedure reads one card from the card reader. The boot card contains binary code^[23] to read the contents of sector zero of the disk drive, which in turn handles the "operation complete" interrupt from the disk drive and performs additional disk reads to prepare the 1130 for the first punched-card job. The whole process takes about a second to complete.

Recovery procedures

When the IBM 1130 is started, the Supervisor is still in memory and probably intact, as core memory retains its state without power. If the operator concludes that a user program has stalled, the Supervisor can sense a key press to abort the program and skip ahead to the next // card. The Supervisor is not protected against modification by a badly written job, a case that might require that the operator reboot the 1130. Nor was there protection against writing to disk. If the copy of the system software on disk is modified, it can be restored by reloading it from about 4000 binary-coded punched cards (approximately two boxes).

Disk organization

IBM 2315 disk cartridge

2315 compatible disk cartridge.(dimensions 1 3/8 x 15 in.)

The IBM 2310 disk drive stores sectors of 320 words (640 bytes) plus a one-word sector address. A cylinder consists of two tracks on the top and bottom surfaces of the 2315, or of one platter on the 1316 disk pack used in the 2311. Each disk cylinder contains eight sectors. A sector is logically divided by the monitor into sixteen disk blocks of 20 words (40 bytes) each. The disk block is the unit of allocation for files.

The system distinguishes between system cartridges, which contain the monitor and utilities along with user data, and nonsystem cartridges, which contain user data only. All cartridges contain information on cylinder 0, including the defective cylinder table, cartridge id, and a bootstrap program (bootstrap code). On nonsystem cartridges, the bootstrap simply prints an error message and waits if an attempt is made to boot from this cartridge. On a system cartridge this is the cold-start program, followed by a communications area and the resident monitor in sectors one and two. Sectors three through five contain the System Location Equivalence Table (SLET)—a directory of all phases of all monitor programs. Other control information fills out the first track.

The system area is present on system cartridges. It contains the Disk Monitor program, and optionally the FORTRAN compiler, the Assembler, and a core image buffer used for linking relocatable programs. It also contains the user file directories— Fixed Location Equivalence Table (FLET), and Location Equivalence Table (LET),

Following the system area, the cartridge contains up to three logical subdivisions: the fixed area, the user area, and working storage. Both the fixed area and user area store non-temporary programs and data. The fixed area size is defined by DUP, and stores data, and programs in core image format only. It is not repacked when files are deleted. The user area stores data and programs in any format. The boundary between the user area and working storage "floats"— the user area expands as files are added and contracts as it is repacked to reclaim space from deleted files. If a file needs to be modified, the usual process is to use // DUP commands to delete it, which moves any subsequent files back to close the gap, and then give that name to the temporary file as the new version of the file. Rarely modified files thus migrate towards the start of the disk as new files or new versions are appended, and frequently modified files are stored towards the end of the disk.

Working storage starts after the last file in the user area and occupies all the remaining space on the cartridge. It may contain one temporary file created by the system or the user, such as the output of a compiler or an application program. This file is subject to possible deletion at the end of the current job, unless saved to the fixed area or the user area.

All disk files are contiguous disk blocks, thus there is no fragmentation. A program can use and modify named files, but can not expand them beyond their created size. A program which creates more than one file must have all but one pre-allocated by a DUP.

With limited disk space, program source files are normally kept as decks of cards. Users having larger requirements may have a disk of their own containing the operating system, but only their files, and would have to replace the "pool" system disk with theirs and restart the system when their programs are to be run. A system with a second disk drive that can be devoted entirely to one user's code and data provides some relief.

A disk pack or cartridge is initialized for use on the 1130 by the Disk Pack Initialization Routine (DIPR). This routine scans the disk, and writes sector addresses on all cylinders, flags defective sectors, and writes a cartridge id on cylinder zero. DIPR is a Standalone program, which is loaded from cards or paper tape, and accepts the cartridge id from the system console.^[19]

Disk Utility Program (DUP)

The Disk Utility Program (DUP) provides commands for transferring programs, subroutines and data. It is invoked by the job control // DUP card, followed by one or more control cards:^[24]

Other commands, mainly for use by the system administrator, define or expand the Fixed Area, delete the FORTRAN compiler and/or Assembler from the system, and restore correct sector addresses to Working Storage if they have been modified.

The operands have to be placed into fixed columns.The source device code goes in columns 13 and 14, the destination device in columns 17 and 18. These device codes are:

• UA – User Area
• FX – The fixed area (no "extents" as per the 360; just contiguous space)
• WS – Working Storage
• CD – Punched Card/Principal Input device (could be PT: Paper Tape)
• PR – Printer

Optionally, a program name may be coded in columns 21 thru 25, and a count field in 27 thru 30. The interpretation of these fields depends on the DUP function requested.

Programs can be converted to a faster-loading format with the STORECI command, which invokes Core Image Builder (DM2's counterpart to the 360's Linkage Editor). Alternatively, a program can go through this process each time it is to be run, and for infrequently used programs this is preferred in order to conserve disk space.

The following control card instructs DUP to take the current contents of working storage and move it to the user area naming it PROGM. DUP knows the size of the file in working storage. The size of the user area will be increased by the size of the file, and the size of working storage will be decreased correspondingly.

IBM 1130 DUP control card example

Peripheral devices

IBM 1132 line printer

IBM 1442 card reader/punch

IBM 1627 drum plotter.

Disk memory is used to store the operating system, object code, and data, but source code is kept on punched cards.

The basic 1130 came with an IBM 2310 voice-coil actuated disk drive, called "Ramkit", from IBM's General Products Division in San Jose.^[7]: 497 Their pizza-box-sized IBM 2315 single platter cartridges holds 512,000 words or 1,024,000 bytes (less than a 3.5" HD floppy's 1.44MB or even the 5.25" HD floppy's 1.2MB). Transfer rate is 35,000 words per second (70 KB/sec) using cycle stealing.^[25]

The IBM 1053 console typewriter uses an IBM Selectric mechanism, which means one could change the typeface or character set by replacing a hollow, golf-ball sized type element. There is a special type element available for APL, a powerful array-oriented programming language using a special symbolic notation. A row of 16 toggle switches on the console typewriter can be individually tested from within programs, using the special Fortran statement IF (SENSE SWITCH i), for example.

Other available peripherals included:

• Printers – the IBM 1132^{[note 4]} and IBM 1403^{[note 5][26]} line printers
• Punched-card – the IBM 1442 card reader/punch and the IBM 2501 card reader
• Paper tape – the IBM 1055 paper tape punch, the IBM 1054 paper tape reader, and the IBM 1134 paper tape reader
• Disk – the IBM 2311 Disk Drive
• Magnetic tape – From 1968, IBM 2415 Magnetic tape data storage drives were available as an RPQ.^[27]
• Graphics – IBM 2250 Graphic Display Unit.
• Color Pen Plotter – IBM 1627 drum plotter.
• Optical Mark Reader – IBM 1231 Optical Mark Page Reader ^[28]
• Communications – Synchronous Communications Adapter (SCA). The IBM 1130 MTCA, for Multiple Terminal Control Adapter, announced in 1970^[29] allowed up to four 2741 terminals to be connected to an IBM 1130, for use with APL.

To simplify the design of peripheral devices, these rely on the processor. The card reader has no memory buffers, but instead gives the CPU a level-zero (highest priority) interrupt after each individual column of the card has been read. If the CPU does not respond and store the twelve bits of data before another such interrupt indicates that the next column has been read, data will be lost. Similarly, the 1132 printer relies on software in the 1130. When a letter such as A comes into position, the CPU has to analyze a buffered line of text and assemble an array of bits that will indicate to the 1132 which print positions should be printed with A. If the CPU can not respond before the A rotates out of position, print speed could be severely degraded.

Other peripherals accept text in a device-specific code convenient for its hardware. The CPU has to translate it to or from the EBCDIC code in which the CPU processes the text.

Instruction set overview

Instructions have short (one-word) and long (two-word) formats. Most computational, load, and store instructions reference one register (usually ACC) and a memory location. The memory location is identified, in the short format, by an 8-bit signed displacement from either the current address or one of the index registers; or in the long format, by a full 15-bit address, which can be indexed and specify indirection. Memory is addressed in units of words.

The 1130 supports only single-precision and double-precision binary data natively (16 and 32 bits) stored in big-endian format. Standard- and extended-precision floating-point (32 and 48 bits) and decimal data are supported through the use of subroutines.

Conditional transfers are based on (a) the current contents of the accumulator, or (b) the carry and overflow indicators set by a preceding operation. Transfers can be by skip (which assumed that the next instruction was short) or by branch. A skip occurs if any of the specified tests are true. A branch occurs if none of the specified tests were true.

Main Registers:
IAR = Instruction Address Register
ACC = Accumulator
EXT = Extension Register
XRx = Index Registers: x = 1,2,3
      Implemented as memory words 1,2,3, not as hardware registers.

Condition tests:
Z  Accumulator zero
-  Accumulator negative
+  Accumulator positive
E  Accumulator even
C  Carry indicator off
O  Overflow indicator off

1130 Instruction Set Mnemonics:
LD   = Load ACC                   STO  = Store ACC
LDD  = Load Double (ACC & EXT)    STD  = Store Double (ACC & EXT)
LDX  = Load Index                 STX  = Store Index
LDS  = Load Status                STS  = Store Status
A    = Add ACC                    AD   = Add Double
S    = Subtract ACC               SD   = Subtract Double
M    = Multiply                   D    = Divide
AND  = Boolean AND                OR   = Boolean OR
XOR  = Boolean Exclusive OR
SLA  = Shift Left ACC             SLT  = Shift Left ACC & EXT
SLCA = Shift Left and Count ACC   SLC  = Shift Left and Count ACC & EXT
SRA  = Shift Right ACC            SRT  = Shift Right ACC & EXT
RTE  = Rotate Right ACC & EXT
BSC  = Branch or Skip on Condition (Modifier dependent)
       i.e. BP BNP BN BNN BZ BNZ BC BO BOD
BOSC - Branch Out or Skip Conditionally (alternate for BSC with bit 9 set)
       Exits current interrupt level.
BSI  = Branch and Store IAR
MDX  = Modify Index and Skip (Increment IAR one if a sign change or becomes zero)
WAIT = Halt                       NOP  = No Operation (alternate for SLA 0)
XIO  = Execute I/O

1800 Additional Instruction Mnemonics:
CMP  = Compare ACC                DCM  = Double Compare ACC & EXT

Equivalent Mnemonics
The disk assembler introduced several mnemonics equivalent to existing
instructions intended to make the programmer's intent clearer:
SKP - Skip on condition, equivalent to a short BSC
B   - Branch unconditionally, equivalent to BSC with no conditions specified
BP  - Branch Accumulator Positive, equivalent to BSC specifying '+' condition
BNP - Branch Accumulator not Positive
BN  - Branch Accumulator Negative
BNN - Branch Accumulator not Negative
BZ  - Branch Accumulator Zero
BNZ - Branch Accumulator not Zero
BC  - Branch on Carry
BO  - Branch on Overflow
BOD - Branch Accumulator Odd
MDM - Modify Memory, equivalent to unindexed long-format MDX
XCH - Exchange Accumulator and Extension, equivalent to RTE 16

Short instruction format (one 16 bit word):
                       1
Bits    0...45678......5
        OP---FTTDisp----

OP    is Operation
F     is format 0 = Short
TT    is Tag
Disp  is Displacement

Long instruction format (two 16 bit words):
                       1               1
Bits    0...456789.....50..............5
        OP---FTTIMod----Address---------

OP    is Operation
F     is format 1 = Long
TT    is Tag
I     is Indirect bit
Mod   is Modifier

Effective Address Calculation (EA):
          F = 0            | F = 1, I = 0     | F = 1, I = 1
          Direct Addressing| Direct Addressing| Indirect Addressing
-------------------------------------------------------------------
TT = 00 | EA = Displ + IAR | EA = Add         | EA = C/Add
TT = 01 | EA = Displ + XR1 | EA = Add + XR1   | EA = C/Add + XR1
TT = 10 | EA = Displ + XR2 | EA = Add + XR2   | EA = C/Add + XR2
TT = 11 | EA = Displ + XR3 | EA = Add + XR3   | EA = C/Add + XR3
-------------------------------------------------------------------
    Disp = Contents of displacement field
     Add = Contents of address field of instruction
       C = Contents of location specified by Add or Add + XR

Reserved memory

The lowest addresses of core memory have uses dictated either by the hardware or by convention:

Programming

SIMPL: DC     *-*    This is the entry point, filled with a zero initially.
       (whatever the routine does)
       B    I SIMPL  Return by an Indirect branch, to the address found in location SIMPL.
       END    SIMPL  Instructs the assembler that the source for routine SIMPLE is complete.

       BSI  L SIMPL  Call SIMPL. L (Long) is needed if SIMPL is more than -128 or +127 words away.

      DC       *-*            A word into which BSI stores the return address.
      B    L   SIMPL          Branch to the start of the library function.

SIMPL STX   1  RCVR1+1        Save the caller's value of XR1 at a nearby location.
      LDX  I1  *-*            The linkage loader changes the address word to point to the transfer vector.

      STX   1  RETN+1         Store XR1 to prepare to use it as a return address.
RCVR1 LDX  L1  *-*            SIMPL's first instruction modified this address.  Now,
*                              restore the original value of XR1.
RETN  B    L   *-*            This instruction was modified two instructions ago; return.

  BSI L  SIMPL
  DC     X      The address of X, on which SIMPL is to operate

  LD  I1 0      Load the value of the first parameter (offset 0) into the accumulator

  LD  L  X      Load the value of X into the accumulator

   M = 3*IOR(I,J) + 5

  BSI  L IOR    Two-word jump to the start of the IOR function.
  DC     I      A one-word in-line parameter: The address of I.
  DC     J      A one-word in-line parameter: The address of J.

  LD   L I      Load accumulator with I (two-word instruction)
  OR   L J      OR accumulator with J   (two-word instruction)

Programming examples

The examples can be executed on the IBM 1130 emulator available at IBM 1130.org.

 // JOB
 // ASM
 *LIST
                     * LCARD.ASM - LIST A DECK OF CARDS TO LINE PRINTER
                     *
                     * PROGRAM
                     *    NEW PAGE ON PRINTER
                     * A  READ A CARD
                     *    CONVERT FORMAT
                     *    PRINT A LINE ON PRINTER
                     *    GOTO A
                     *
                     START LIBF    PRNT1    GOTO NEW PAGE ON 1132
                           DC      /3100    PRINTER CHANNEL 1-NEW PAGE
                     *
                     NEXTC LIBF    CARD0    READ FROM 1442 CARD READER
                           DC      /1000    CONTROL TO READ
                           DC      CBUFF    STORE 80 COLUMNS
                     CINP  LIBF    CARD0
                           DC      0
                           B       CINP     LOOP UNTIL CARD IS READ
                     *
                           LIBF    ZIPCO    CONVERT CARD TO PRINTER
                           DC      /1100    UNPACKED IN, PACKED OUT
                           DC      CBUFF+1  INPUT BUFFER
                           DC      PBUFF+1  OUTPUT BUFFER
                           DC      80       CHARACTER COUNT
                           CALL    HLEBC    HOLLERITH TO EBCDIC
                     *
                           LIBF    PRNT1    PRINT 80 CHARACTERS
                           DC      /2000    CONTROL CODE TO PRINT
                           DC      PBUFF    PRINT BUFFER
                           DC      PERR     PRINT ERROR
                     POUT  LIBF    PRNT1    CHECK FOR PRINT COMPLETE
                           DC      0
                           B       POUT     LOOP UNTIL COMPLETE
                     *
                           B       NEXTC    READ NEXT CARD
                     *
                     * DATA
                     *
                     CBUFF DC      80       80 COLUMNS PER CARD
                           BSS     80
                     *
                     PBUFF DC      40       40 WORDS 80 CHARACTERS
                           BSS     40
                     *
                     PERR  DC      0
                           B    I  PERR     THIS RETURNS TO THE
                     *                       PRINTER ERROR HANDLER
                     *                       WHICH WILL TERMINATE THE PROGRAM
                     *
                           END     START    PROGRAM ENTRY POINT
 // XEQ
 TEST DATA 1
 HELLO WORLD
 TEST DATA 2

Competing systems

In the same year as the 1130's introduction, Digital Equipment Corporation introduced the smaller, cheaper, and better-selling 12-bit PDP-8, recognized as the first successful minicomputer.

Influence of the 1130

• Brian Utley was the 1130s project manager during its development and introduction. Brian said at the third 11/30 party that before IBM Marketing named the 1130 it was known as the Small Engineering Computer System or SECS.^[35] The initial architecture was 18 bits but was changed to 16 bits due to the influence of the System/360 development. The full dialogue of his 2005 presentation is available at IBM1130.org.
• Notable software designer Grady Booch got his first exposure to programming on an IBM 1130:^[36]

... I pounded the doors at the local IBM sales office until a salesman took pity on me. After we chatted for a while, he handed me a Fortran [manual]. I'm sure he gave it to me thinking, "I'll never hear from this kid again." I returned the following week saying, "This is really cool. I've read the whole thing and have written a small program. Where can I find a computer?" The fellow, to my delight, found me programming time on an IBM 1130 on weekends and late-evening hours. That was my first programming experience, and I must thank that anonymous IBM salesman for launching my career. Thank you, IBM.

• LISP guru Guy Steele wrote a LISP interpreter for the IBM 1130 when he was in high school (Boston Latin School, which had an IBM 1130 for student use).^[37][38] His code and documentation for LISP 1.6, along with a summary of current work in getting it to run under simulation, is available at IBM1130.org.
• Chuck Moore wanted to call his new language "Fourth" but the IBM 1130 operating system was limited to five-character names, so it wound up being called FORTH.^[39]
• Dan Bricklin, creator of the VisiCalc program, got his start in programming when he learned and used the IBM 1130 as part of the National Science Foundation Computer/Math Summer Project for high school students, given at the University of Pennsylvania in 1966.^[40]
• An IBM 1130 with 8 kilowords of core was used for the world's first full-time Search for Extraterrestrial Intelligence research at The Ohio State University Radio Observatory. This equipment detected the Wow! signal.^[41]
• Charles Goldfarb, the father of SGML, describes a job installing a typesetting system based on an IBM 1130 that "eventually changed my career", driving him towards generic markup:^[42]

The system was an IBM 1130 computer, a machine the size of a desk with 8 KB of main memory, a 512 KB disk drive, a Teletype CX paper tape reader and BRPE paper tape punch, and a Photon 713 photomechanical typesetter. The assignment was my first experience with managing a machine-readable document database: I learned to roll the punched paper tape carefully so that it could be stored neatly in cylindrical waste paper baskets.
In the meantime, though I didn't know about it, the roots of generalized markup were being planted. Historically, electronic manuscripts contained control codes or macros that caused the document to be formatted in a particular way ("specific coding"). In contrast, generic coding, which began in the late 1960s, uses descriptive tags (for example, "heading", rather than "format-17").

• Alan Kay used the IBM 1130 in early GUI work for his Ph.D. thesis in 1969.^[43]
• Hutchinson Central Technical High School ("Hutch Tech") in Buffalo, NY used the IBM 1130 in the nation's first four-year high school computer science curriculum in 1969. Robert Santuci was the computer science program head and taught classes in programming and inductive logic.^[44]
• An engineer from IBM was hired by Signetics and incorporated a number of architectural features from the IBM 1130 into the Signetics 2650 single-chip processor.^[45]

1130s today

Out of an estimated 10,000 systems produced, the following are known to exist as of 2024:

• ACONIT in Grenoble, France has a complete 1130 system.^[46]
• The Computer History Museum (Mountain View, California) has an 1130 system.^[47]
• COSECANS (Basel, Switzerland).^[48]
• The National Museum of Computing (TNMOC) (Bletchley Park, United Kingdom) has a complete 1130 system.^[49][1]
• The University of Stuttgart (Germany) has a functional 1130 system.^[50]
• Carl Claunch is currently restoring an 1130 system.^[51]

Apocrypha

Speculation on why the product was given the number 1130 centered on the following possibilities:

• That, since the 1130 was a small scientific machine, the number was chosen by multiplying 360 (as in IBM 360) by π.
• That 11:30 was the time of day that product planners reached an impasse regarding what to call the product.
• That the 1130 was IBM's 11th Computer Design, and it had 30 instructions.

Others have speculated that the existence of the IBM 1130 explains why no computer designated "11/30" ever appeared in the PDP-11 family of machines.^[52]

See also

• IBM mainframe
• List of IBM products

Notes

References

External links

Wikimedia Commons has media related to IBM 1130.

• IBM Archive: IBM 1130 press releases, chronology, photos, facts folder.
• IBM 1130.org Norm Aleks and Brian Knittel site which has significant information about the 1130 and a downloadable simulator that supports the DMS R2V12 and APL environments.
• www.ibm1130.net is Howard Shubs' site dedicated to the 1130.
• Arnold Reinhold's personal account of the 1130. Text from here has been incorporated into this article with permission
• A set of PDFs made up of scanned IBM 1130 manuals
• Kym Farnik's page on Retro Computing specifically the 1130
• A discussion about the (then) Angle Park computing centre which was equipped with IBM 1130's
• Bob Rosenbloom's IBM 1130 Photos
• IBM 1130 material at Columbia University, Computing History site.
• A Flickr collection of detail photos taken by Peter Vaughan of an IBM 1130 at The National Museum of Computing