GE 235 System Manual

@En235

SYSTEM

MANUAL

COMPUTER DEPARTMENT

GENERAL ELECTRIC COMPANY

In the construction of the equipment described, General Electric reserves the right to reasons of improved performance and operational flexibility.

modify the design for

TITLE SECTION INTRODUCTION

PROGRAMMING AIDS SYSTEM CONTROL OF INPUT-OUTPUT PERIPHERAL DEVICES CENTRAL PROCESSDR GE-235 PUNCHED CARD EQUIPMENT GE-235 HIGH-SPEED PRINTER GE-2 35 MAGNETIC TAPE SUBSYSTEM GE-235 MASS RANDOM ACCESS DATA STORAGE GE-235 PERFORATED TAPE EQUIPMENT

GE-235 12-POCKET DOCUMENT HANDLER GE-2 35 DATANET- 15 DATA TRANSMISSION SUBSYSTEM GE-2 35 CUSTOM DIGITAL INPUT/OUTPUT EQUIPMENT

G-235 SYSTEM INSTALLATION DATA

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PAGE

1 1

ALPHABETIC LIST OF GE-235 GAP INSTRUCTIONS REPRESENTATION OF GE-235 CHARACTERS INDEX

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2-14

17-20

The GE-235 is the fastest, most versatile memberof the GE-200 Series of information processing

systems (GE-215, 225, and 235). Like the other members of this family, the GE-235

complemented by a full range of powerful programmingtools. Together, the equipment and programming tools provide an integrated system adaptable to a wide variety of business, scientific, and engineering applications.

The basic design philosophy

oftheGE-235 system is the same as that of the GE-215 and 225, which have proved themselves fast, accurate, reliable, and economical in widely divergent fields. This design similarity makes the

GE-235upwardcompatiblewith

the GE-215 and 225 in respect to logic, programming, and coding. As a result, mostprograms and applications originally designed for the other members of the family can immediately be processed on a GE-235 having the same system configuration. Only in the relatively few programs containing timing loops, minor changes may

necessary.

GE-235 INFORMATION PROCESSING SYSTEM

The basic system comprises a central processor with a six-microsecond core memory, card or

pe~forated tape input andoutput, electric typewriter input and output, and an operator's control con-

sole. The system configuration can readily be expanded to fit increasing information processing

needs. Equipment available includes:

Magnetic core memory

Card readers Card punch

400 or 1000 cards per minute

100 or 300 cards per minute

4096-, 8192-, or 16,384-word capacity

Perforated tape reader Perforated tape punch Magnetic tape handlers

15,000/41,600 characters per second (at 200/555.5 bits per inch)

Mass random access data storage

34.4 million numeric digits per unit

High-speed printers

per minute,

Document handler

Data communication controllers

Floating point arithmetic capability (through the Auxiliary Arithmetic Unit)

An outstanding feature

system, allowing great flexibility in system configuration. Some typical system configurations for various applications are shown on the following pages.

Programming aids available for the GE-235 include:

on/off line

250 or 1000 characters per second

110 characters per second

read and write 15,000 characters per second (at 200 bits per inch)

(MRADS)

900 alphanumeric lines per minute, on line, or 900 alphanumeric lines

reads and sorts 1200 documents per minute, on or off line

that up to ten input-output devices may be operated concurrently within the

18.8 million alphanumeric characters or up to

GECOM be used with:

COBOL-type statements (specific, simplified English language statements) ALGOL-type statements (algebraic expressions) TABSOL (structured decision tables) GECOM Report Writer (for programming business reports)

FORTRAN

ZOOM

WIZ

GAP

the general compiler, an all purpose, problem-oriented language program that may

a scientific compiler

a macroassembly system

a highly competent, one-pass algebraic compiler

a fast, compact, machine-oriented assembler

I- 2

Standard report generators, sort/merge routines, BRIDGE (an ope rating system), GE-235/~~~ (a major network analysis technique),

Thus, the GE-235 provides economical solution of data processing and scientificproblems, and for potential growth in desired areas. The characteristics and capabilities of this new member of the GE-200 Series are fully described in this manual. However, detailedinformationfor operating and programming the system

in separate manuals on these subjects.

all

andother specializedprograms and routines are also available.

the tools for effective management decision-making, for fast and

I-

CENTRALPROCESSOR

CARD READER

HIGH-SPEED PRINTER

CARD PUNCH

SYSTEM CONFIGURATION FOR ENGINEERING CALCULATIONS OR REPORT GENERATION

HIGH- SPEED PRINTER

CARD PUNCH

fl"=-,

CENTRAL PROCESSOR

AND AUXILIARY

ARITHMETIC UNIT

MAGNETIC TAPE

UNIT

C..

CARDREADER

---my

(1000

CPM)

SYSTEM CONFIGURATION FOR SCIENTIFIC CALCULATIONS OR DATA RETRIEVAL AND REDUCTION

MAGNETIC TAPE UNIT

T+.

+*q!Fi

_C--

CARD PUNCH

---

PERFORATEDTAPE

HIGH-SPEED * PRINTER

DATANET-

--2

-!u7*-

z7-;

-~-'

-T

CENTRAL PROCESSOR

'v:-???

CARD READER

-1

DATA COMMUNICATIONS SYSTEMS

SYSTEM CONFIGURATION FOR BUSINESS OR MANUFACTURING

HIGH-SPEED

PRINTER

MAGNETIC TAPE UNIT

CARD PUNCH

CENTRAL PROCESSOR

DOCUMENTHANDLER

SYSTEM CONFIGURATION FOR BANKING

CARD READER

PROGRAMMING AIDS

The General Electric Computer Department has developed a large library of programming aids to help the programmer communicate with the GE-235 and simplify the task of producing useful results from the computer. generators and special programs designed to enhance the use of the GE-235 information processing system.

This section describes some of the available programming tools: compilers,

GECOM,

The General Compiler (GECOM) System introduces a fresh, versatile approach to computer communication. This exclusive General Electric product makes available in one package both proved and newly developed programming techniques. GECOM accepts many languages, so problem statements may be written in familiar terminology. The source languages available to the General Compiler are broad and comprehensive.

GECOM will process English language sentences (COBOL-type statements), algebraic expressions (ALGOL-type statements), structured decision tables ation. combination of the language features for any specificprogram run. Because the machine coding

derived directly from the logic of the problem statement, program check-out on the GE-235 may be

done at the logic level.

Because GECOM problems are written in familiar languages, they can be more easily read and understood. approach allows the user to accommodate the more important common coding languages and still

incorporate later changes conveniently. Several distinct advantages over manual programming

methods can be realized.

GECOM automatically produces a documented record of the program it produces. A permanent

record of the program, in its original source language form and with a detailed listing of its transformation to machine instructions,

THE

The user may select only that portion of the system applicable to his needs, using any

GENERAL COMPILER

(TABSOL), and a language for report gener-

In addition, program format provides a high degree of standardization. The selected

available for reference, revision, or augmentation.

Because plans call for implementing GECOM on the General Electric family of general-purpose computers, programming conversion costs are reduced as installationsoutgrow their present com-

puter equipment.

Using familiar language sharply reduces personnel training time and expense. Manual coding eliminated and debugging cut to a minimum. ~hus, a machine program may be produced quickly and efficiently.

COBOL came into being as a result of a conference on Data Systems Languages sponsored by the U. S. Department of Defense. Computer manufacturers and users developed the language called COBOL languages.

computers. The language first available with the General Compiler

(Common Business griented Language) to achieve standardization of data processing

COBO~

reduces progra&ing effort and achieves a more effective utilization of

based primarily on COBOL,

which satisfies the needs of the broadest spectrum of data processing applications. COBOL is so close to English syntax that it can easily be read and understood by management, systems, and accounting personnel. As a result, close coordination between management and computer application is both practical and efficient.

COBOL

well suited to creating and processing information contained in data files.

In contrast, ALGOL provides an excellent means for expressing the mathematics and logic associated with scientific applications.

ALGOL was developed by an international group prompted by a growing interest in a standardized notation for numerical methods for computers.

ALGOL

(ALGOrithmic Language) has proved to be far superior to any of its predecessors and has enjoyed the first widespread acceptance and respect accorded a computer language. ALGOL notations are gaining acceptance internationally in numerical methods, text-books and university classes.

TABSOL, the language of decision making, resulted from a need for a language that could solve an unwieldy number of sequential decisions, without involving extensive data file processing or pro-

found mathematics.

CEHERAL~

C~.,",,.

.1...,.

ELECTIIC

1.7.

.0,",1.

A.110..

OENERAL COMPILER SENTENCE FORM

,3,,.,,,,

SAMPLE TABSOL TABLE

TABSOL depicts, by means of tables, the relationships of logical decisions that are written in terms

of the conditions to be satisifedandthe subsequent action to be taken. The

vides a readable, understandable table of decisions.

TABSOL structure pro-

TABSOL encompasses both scientific and business applications.

ALGOL-type statements within the framework of the table, thus providing an even more efficient

method for stating the logic of complex information systems.

The GECOM Report Writer ming of business reports. Readily understandable program documentation and ease of preparation of new and revised report

In brief, the Report Writer performs any or all of the following functions:

Prints report headings once at the beginning of the report

Prints report footings once at the end of the report Maintains page control by line count and or skip to a new page at specified line printings Maintains line spacing on the page Prints page headings at the top of each report page

Prints page footings at the bottom of each report page Numbers pages Issues detail or body lines of the report

an extension to the General Compiler that simplifies the program-

are realized by use of this tool.

GECOM accepts COBOL and

Accumulates detail field values conditionally or unconditionally to one or more levels of total

Counts detail lines and/or detail conditions to one or more levels of total

Detects control breaks at one or more levels so as to: a. Control the tabulation procedure

b. Issue logical control totals

c. Issue logical control headings

Edits data fields for reporting (for example, comma, decimal point, and dollar-sign insertion and zero suppression)

The COBOL-61 to GECOM Translator converts programs described in COBOL-61 language into language acceptable to GECOM. The source language of the basic compiler is based in part on COBOL-60. The translator enablesGECOM toprovide for additional functions defined in COBOL-61 specifications.

FORTRAN FORTRAN

Using this compiler with the GE-235, a source program written in the language of FORTRAN

scientific compiler, will produce an assembled program ready for use.

FORTRAN II Compiler With Card Input-Output

This compiler will compile a FORTRAN I1 source program on a GE-235 system with a minimum input-output configuration. The full FORTRAN language (magnetic tape operations, for example, are omitted).

ZOOM

Simplicity and flexibility of coding are principal features of the macroassembler called ZOOM (in some respects a compiler). The simplicity of ZOOM coding is illustrated by the fact that the programmer writes algebraic expressions with such ordinary symbols as the plus, minus, and equal signs. Since they are easily read, the expressions are easily and quickly checked for errors.

ZOOM translates these algebraic expressions into near optimum GAP coding. To the programmer who has a working knowledge of GAP, programs and produces near optimum object programs. Input of GAP coding and ZOOM statements; output can be punched cards, magnetic tape, or printer

listings.

Compiler

II,

not implemented in this compiler

ZOOM allows for more condensed and readable symbolic

punched cards with combinations

Engineers and other users of the GE-235 who are not primarily programmers will find the WIZ

System a simple, easy-to-use algebraic compiler. The compiler translates source programs

written in the simple WIZ language, usingordinary mathematical symbols, into GE-235 object pro-

grams ready to run. WIZ produces GE-235 instructions on cards at a rate of 500 to 700 instructions per minute. WIZ makes iteasyfor the user to perform either simple or complex calculations and print the results in edited form.

WIZ works with both floating point and fixed point numbers and handles typical algebraic and

trigonometric problems quickly and easily. Modification I permits use of paper tape as well as

punched cards. Use of the optional

time of the object program.

AAU with the WIZ System significantly decreases the run

GAP, THE GENERAL ASSEMBLY PROGRAM

The General Assembly Program allows the programmer to write instructions for the GE-235 computer in symbolic notation rather than in the absolute code of the computer. Mnemonic codes for each instruction are carefully chosen to provide significance to the user. Memory addresses may be

assigned by using decimal notation or by using symbolic notation chosen for maximum convenience to the particular program or programmer. To extend the use of the General Assembly Program the programmer can call on various subroutines (described below) as required by the

program. The General Assembly Program also provides facility for assembling of programs in

either absolute or relocatable form.

A wide range of assembler (pseudo) operations are available as follows: ALF BSS The BSS DDC DEC

EJT

END

EQO

EQU FDC

LOC This operation performs the same function as the ORG operation but the contents are

LST

The ALF

This This is used to enter a single-word decimal constant in the object program.

This operation causes the printer to slew the GAP listing paper to the top of the following

page.

The END Performs the same function as the EQU operation but the operand is assumed to be an

octal number.

Used to over-rule the normal memory assignment performed by the assembly program.

This scale

number.

assumed to be in octal form. This pseudo-operation may be used to start the listing again after it has been suppressed

by the NLS.

used to enter an alphanumeric constant in the program.

used to reserve a block of memory storage.

used to enter a double-word decimal constant in the object program.

(~nd of Program) indicates the end of the program to be assembled.

used to enter a floatingpointdecimal constant in the object program. If no binary

specified, determines the binary scale and yields a normalized floating point

MAL

NAL

This pseudo-operation can be used to specify from on one card.

A/N

This pseudo-instruction causes any the 2's complement form.

constant or group of constants to be assembled in

to 9 words of alphanumeric constants

NAM

Permits a program name to be printed at the top of each page of the GAP listing.

NLS OC T ORG PAL

REM

SBR

SEQ

TCD

ZXX

Suppresses listing of the object program during assembly. The OCT converts up to seven octal digits into a binary equivalent. ORG (Origin) This pseudo-operation can be used to specify from

used to indicate the location of the first instruction of the program.

to 9 words of alphanumeric constants

on one card. The last word generated will have the sign set to terminate a print line. The pseudo-operation PLD will cause the assembly program to punch loader cards. When

the PLD pseudo-operation is encountered, all cards from that point to the end of the assembly will be punched in loader format.

The REM programmer's remarks immediately following are not processed by the assembly

but they do appear on the final program listing.

This pseudo-operation

used to call a specified subroutine master tape during assembly.

Checks the sequence number of each card against the sequence number of the previous card.

Generates an instruction that transfers control to the location specified in the operand field, at execution time; however, does not indicate end of assembly.

The ZXX pseudo-operation is used to set the operation bits of the assembled instruction to any desired configuration. The operand can be decimal or symbolic, and indexing

optional. In use, a Z is placed in column 8 with the two octal digits (XX) desired as an

and

operation code in columns

10.

SAMPLE GAP CODING

SUBROUTINES, SERVICE ROUTINES AND BRIDGE II

Subroutines

Subroutines are designed to handle, manipulate, move, or sort information within the computer memory. Some of the important routines accomplish the following:

Conversion of data from one radix to another (octal, binary; BCD)

Word replacement

Internal memory sort

To solve problems in scientific areas, mathematical routines are available to calculate complex

functions and mathematical procedures such as:

Sine-cosine, square root, arctangent, exponential, and logarithm Matrix transposition, inversion

Scalar multiplication

Linear simultaneous equations

Multiple regression

Roots of a polynomial

Least squares polynomial fit

Linear programming

Service Routines

The main functions of service routines are to assist in debugging programs and in simplifying oper-

ating procedures.

These routines have been prepared in symbolic and/or object program form.

Service routines to perform tasks such as the following are available:

Reset memory Dump memory to cards, magnetic tape, paper tape, or printer

Load programs into memory

Trace programs

Compare, correct, and print out contents of tape

Correct cards

Scan memory Convert, analyze, and relativize card decks

Reproduce cards or print out contents

Bridge Bridge

by the programmer, Bridge

The functions of Bridge execution. For installations that have a steady work load, use of Bridge

SIMULATORS AND GENERATORS

a tape maintenance and run sequencing program. Upon the use of simple instructions

provides such functions as:

Run collection and sequencing from cards or tape

Tape correction of binary or symbolic programs Dating of magnetic tape, using either date created or current date Blocking of tape records Provisionof run-to-runlinkage

Provision of altering run sequencing Combining of runs with subroutine or relocatable sections

Provision for loading priority programs for use with API

I1 are directed by control cards that establish the run sequence for run

I1 reduces over-all time.

Forward

The Forward Sort and Merge Generator produces tailored card or tape programs to efficiently sort and merge GE-235 data files, The sorts and merges are tailored at generation time according to descriptive parameters written by the user. Extensive options that allow for use of GAP coding enable users to attain complete flexibility in data format and selection and to utilize media other than tape.

IBM-650 Simulator

The IBM-650 Simulator accepts IBM-650 System programs the required routines to simulate the IBM-650 computer commands, and produces the same results and outputs as the IBM-650 computer. An existing IBM-650 program need not be written in GE-235 language in order to run on the GE-235 computer.

Sort/Merge Generator

input/output

anddata as input, selects and executes

Potential users of the GE-235 who have the IBM-650 computer can make a smooth transition to the GE system through the use of simulators provided by General Electric.

The simulator program achieves the following objectives without loss of accuracy or flexibility:

Simulates the basic IBM-650 System, with 2000 words of drum memory, one 533 card reader, and punch with alphabetic device.

An extended version provides the capability of core storage, index registers, floating point, and magnetic tapes. The simulator program runs on the GE-235, with

atleast 8192words of memory, card reader and card punch, and

typewriter. Control cards preceding the IBM-650 program deck define the IBM-650 plugboard wiring

and console switch settings. Can be modified to include other IBM-650 configurations or features with a minimum of

programming effort. Documentation

detailed and complete so that features peculiar to

certain applications may be readily incorporated.

LGP-30 Simulator

The LGP-30 Simulator executes the Royal

McBee LGP-30 system instructions in the GE-235 and

produces essentially the same results and outputs as that computer.

SPECIALIZED PROGRAMS

Special needs of computer users are filledby specialized programs such as the text searching system and the

GE-235/cP~ program. Other programs are tailored to needs of a specific industry

or user.

The Text Searching System

The Text Searching System permits retrieval of information from texts.

The System consists of three principal programs. One converts texts (written in a natural or artificial language) into a form suitable for searching. A second program compiles programs to search the texts for requested symbol occurrences. The third program executes the compiled programs to search converted texts and announce the search results.

The

GE-235/Cp~ program adapts a major network analysis technique to the GE-235. Complex projects (such as new product introduction, large constructionprojects, and assembly-line planning) consisting of as many as 2100 activities and

1000 events can be analyzed by the GE-235 in minutes. Alternate schedules with optimum time and cost data, or other major project parameters, are produced as a printed output. The least an 8K memory,

magnetic tape handlers, a card reader, and a printer.

GE-235/~~~ program can be used with GE systems having at

BankPac

series of generalized programs, called BankPac, have been tailored to the needs of commercial

banks. General Electric prepares broad programs to do such jobs as updating and maintaining files, issuing reports, functions. The user can readily add desired detailed programs. BankPac program will cover demand deposit accounting, installment loans, savings accounts, transit items, and personal trusts.

making customer statements, and the handling of many other normal banking

Electric Utility Routines

Groups of Electric Utility Routines were tailored to needs of individual utility companies. These programs are designed to compute load flow, optimal loading, load duration, gas flow and pressure, and short circuit conditions.

SYSTEM CONTROL OF INPUT-OUTPUT PERIPHERAL DEVICES

In a GE-235 system up to ten input-output (I/o) devices of various types may operate simultane-

ously with the central processor and with each other. This truly active configuration is extremely flexible and efficient; it is capable of a maximum throughput of 55, 000 20-bit words per second, plus card reading, per second, plus card reading, card punching and printing, by the addition of optional dual access 1/0 controller selector channels.

This performance is the result of two significant design concepts:

Each 1/O device controls itself and executes its own 1/0 commands.

All central processor have access to memory on a time-sharing basis.

card punching and printing. The throughput may be doubled to 110, 000 words

I/O

devices (with exception of perforated tape reader/punch and typewriter) and the

INDEPENDENT-CONTROL OF

The

individual operation of each 1/0 device is determined by the controller through which it attached to the system. The controller receives the commands appropriate to it (such commands as to start, these commands without further instruction. central processor

stop, edit data, and rewind tape are typical) from the central processor and executes

free to continue with the succeeding item in the program.

TIME-SHARIIVG OF MEMORY ACCESS BY

Orderly and efficient time-sharing of memory access among the central processor and 1/O

devices of the GE-235

Allowing only one system element to have access to memory at one time. Allowing each element access to memory on a priority schedule when it needs it and

causing

These conditions are satisfied in the GE-235 by the built-in priority control logic. The success of this feature, in fact, accounts for the high efficiency and capacity of the system and the simultaneity of operation of

ensured by:

to relinquish access when it does not.

its

Garious elements.

1/0

DEVICES

Thus, having given a command to a controller, the

1/0

DEVICES

Priority Control and Time-Sharing

The GE-235 priority control feature is shown schematically in the accompanying block diagram. For the numbered channels shown on the diagram, descending priority is from left to right (from 0 to

6).

The channel assigned to a particular 1/0 device depends upon its information transfer

that

is,

rate

its memory access requirements.

For

example, a high-speed printer has a lower priority requirement than a magnetic tape unit,

since a tape controller cannot wait as long for access as a printer controller can without causing

timing errors. If the printer had the higher priority, it could possibly monopolize access to

III-

memory at the expense of the tape unit without increasing its effective printing speed. Thus, the

I/O

most efficient operation follows from assigning the highest-priority channel to the

device

with the highest access speed.

GE-235

MAIN

rlrl

a2."2E

gaaa

PRIORITY CONTROL LOGIC

CARD

READER

,CONTROLLER

A recommended assignment of priorities is:

MRADS Controller Magnetic Tape Controller or MRADS Controller

Magnetic Tape Controller

Document Handler Adapter Datanet Controller, Document Handler Adapter or High-Speed Printer Controller

6 High-Speed Printer Controller

CARD

PUNCH

CONTROLLER

CENTRAL

PROCESSOR

Examples of Time-Sharing

Three examples of GE-235 equipment configurations are shown below, with the relative amounts

I/O

of time consumed in each case by

activity and internal computation.

Example Read cards at 400 cards per minute

Read magnetic tape at 15,000 characters

per second (500-character record)

Print at 900 lines per minute (edited) Total

Percent of total time left for computing:

Example Read cards at 400 cards per minute

Mass random access data storage (read

and write cycle at 200 milliseconds)

Print at 900 lines per minute (edited) Total Percent of total time left for computing:

Example

High-speed card reading at 850 cards per minute Read magnetic tape at 41,600 characters per

second (500-character record) 4.2

Write magnetic tape at 41,600 characters per

second (500-character record) 4.2

Print at 900 lines per minute (edited)

Percent of Total Time

96.9*

98.6*

Total Percent of total time left for computing:

Since execution of many instructions does not require access to memory, actual computing

time may range upward from the amount shown.

90.2*

Overall Effect of Time-Sharing

The overall effect of the GE-235 time-sharing arrangement is to create the most efficient balance

I/O

between

operations and internal computation, regardless of the type of application.

PERIPHERAL SWITCH CONTROL UNIT

The Peripheral Switch Control Unit

many as seven 1/0 device controllers between two GE-200 Series systems. Any

normally connected to one of the numbered priority control channels may be switched by this unit. This switching capability permits optimum utilization of all peripheral equipment for multiple system operation.

The heart of the unit is the switch control console (see the accompanying illustration). The console is console performs two functions: 1) assigns each controller to the desired central processor and 2) assigns the selected priority to each 1/0 device.

Two lighted pushbuttons are associated with each 1/0 device--one on the left of the panel

(SYSTEM Separating each pair of SELECT buttons the priority level of the associated 1/0 device. Additional circuitry actuates one of the ADDRESS SELECT ERROR indicators if more than one controller one system. A vertical column of eight numbered panel indicators marked SELECTED ADDRESS also appears on each side of the panel. on each system.

connected to each

SELECT PERIPHERAL) and one on the right (SYSTEM

an optional feature that makes possible the switching of as

I/O device

1/O device to be switched and to the two central processors. The

SELECT PERIPHERAL).

arow of ADDRESS SELECTION buttons for determining

switched to the same priority level on

These indicators show which priority levels are in use

1/0 DEVICE SWITCH CONTROL UNIT CONSOLE PANEL

110 DEVICE SWITCH CONTROL

UNIT

CONSOLE

CENTRAL PROCESSOR

Frr-

transistorized, single address, general purpose digital computer.

accepts and p/rocesses information from punched cards, magnetic tape, perforated tape, magnetic ink character recognition equipment, communications systems and other peripheral equipment.

provides output to magnetic tape, punched cards, perforated tape, high speed printer,

mass random access data storage, data communications systems and other output media.

Control Console

provides for complete operator control and communication with the system. displays contents of the significant registers and provides control signals to the operator

for the effective monitoring of system operations.

mass random access data storage, data

IV-

Console Typewriter

accepts instructions from the operator.

prints instructions to the operator.

monitors system operations.

prints direct output from the central processor.

MAGNETIC CORE MEMORY

The memory portion of the Central Processor is the immediate-access storage element for the GE-235 system. Both the data to be processed and the controlling instructions are held in memory and are called for by the control unit as required.

The memory is composed of magnetic cores

storing one unit of information, referred to as a bit. The basic unit of memory storage is the

"word"

address.

The size of the basic memory is 4096 words. The memory design allows for an expansion to an

8192-word memory or to a 16,384-word memory without the necessity of expensive retrofits. The 16,384-word memory is divided into two groups of 8192 words each, referred to as the upper

bank and the lower bank.

Minimum instruction word access and execution time is 6 microseconds. to or from memory, including the instruction word time, is accomplished in 12 microseconds; a double word transfer is made in 18 microseconds. are made in one-word parallel form; that is, the word bits are transferred simultaneously.

Internal ferred to memory, and by recomputing and verifying that parity bit when the word is read from memory. The effect of a console

each word consisting of 20 bits plus a parity check bit. Each word has its own unique

checking is accomplished by generating and storing a parity bit when a word is trans-

puity error may be controlled to meet the needs of the application by

STOP/RUN switch operation.

.050 inch in diameter; each core is capable of

data word transfer

The transfer of words to and from memory

WORD FORMATS

The GE-235 can process data in either binary or alphanumeric form. This feature permits both modes of operation to take advantage of the particular characteristics of a given application.

Alphanumeric (BCD) Words

When cards punched in Hollerith code are used as computer input, the information contained in

each

of the 80 columns is automatically converted into a six-bit binary-coded-decimal (BCD)

character. Thus, 3 alphanumeric characters occupy 18 of the 20 bit positions of an alphanumeric

data word. Double length word operations permit the automatic handling of six alphanumeric characters with a single instruction. These convenientword sizes eliminate the need for elaborate

partial word facility. Information must be in the BCD format prior to printing or typing.

The word below illustrates

how 3 random characters are represented in a six-bit (BCD) format

within one word:

The table below illustrates the range of alphanumeric characters which can be represented within

any six bit positions within any word of storage:

Alphanumeric Character

Zone

Bits Numeric Bits

-+v-v-Y-w--vYv

0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1011 1100 1101 1110

GE-235

Alphanumeric Characters

Binary

binary data word consists of

Words

bits plus the sign bit. For example, the decimal number

+49

is represented in binary form as:

Negative binary numbers are expressed in 2's complement form. For example, the decimal

-10

number

is represented in binary form as:

(minus)

IV-

A 20-bit word can accommodate a range of decimal values from -524,288 to +524,287, sometimes referred to as 5-1/2 decimal digits. Double length word operations permit the efficient processing of decimal values between associated with representing numeric data in the true binary format are:

Memory storage efficiency.

An effective increase in the rate with which numeric data can be transferred to and from

magnetic tape.

Increased speed of arithmetic and data handling operations.

+274,877,906,943 and -274,877,906,944. The advantages

Binary and BCD information may be intermixed in memory so as

mode of representing each field in each application, Subroutines are provided to convert numeric

data from BCD to binary, or vice-versa.

to provide the most efficient

Decimal Arithmetic

An optional Decimal Arithmetic feature of the GE-235 provides a decimal add and subtract capability without requiring BCD to binary conversion. These arithmetic operations can be

performed on single decimal words of 3 digits or on double length decimal words of 6 digits.

Automatic carry is provided for larger fields. numbers

+368 and +I5896 would appear in memory.

The examples below illustrate how the decimal

Floating Point Arithmetic

The GE-235 Auxiljary ~ritimetic Unit can be used to advantage in scientific and engineering applications where numerous floating point or double precision arithmetic calculations are required. The logic of the AAU performs double precision fixed point and floating point arithmetic more efficiently than is possible when using mathematical subroutines. However, subroutines may be preferable when floating point arithmetic is done on a limited basis.

Three floating subtraction, multiplication, and division may be done under any of the three modes of operation. All arithmetic is performed in binary mode.

modes of calculation may be performed by the Auxiliary Arithmetic Unit: unnormalized

point, normalized floating point, and fixed point double precision operations. Addition,

During floating point calculations, the data to be operated upon by the internal logic of the

comes

from the main memory of the Central Processor.

floating point number occupies two

words of memory storage and assumes the following format:

Word One

AAU

Bits

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Exponent

Word Two

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Se = Sign Sm= Sign of Mantissa

Exponent

(0 (0

= =

plus;

Mantissa

minus)

The binary point is assumed to be placed before the mantissa. This format produces a binary number with a 30-bit mantissa and a binaryexponent range of -256 to equal to a decimal format of a 9-digit mantissa and a decimal exponent range of -76 to

+255. This is approximately

+76. The

use of two words allows one of the sign positions to be applied to the exponent which, in turn,

allows the use of the full range of the exponent.

The word format for fixed point double precision words in memory

Word One

Bits

as follows:

Sign of Word One

Fixed Point Double Word

Bits

S = Sign of Word Two

lp-lg

Word Two

the Sign of

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GE 235 System Manual

Specifications and Main Features

Frequently Asked Questions

User Manual