ENIACU. S. Army
ENIAC
The Report on the ENIAC consists of five separately bound parts, as
follows:
1. ENIAC Operating Manual
2. ENIAC Maintenance Manual
3. Part I, Technical Description of the ENIAC,
Volume I (Chapters I to VI)
4. Part I, Technical Description of the ENIAC,
Volume II (Chapters VII to XI)
5. Part II, Technical Description of the ENIAC.
Included with the Operating Manual and Parts I and II of the Technical Description are all drawings (see Table 0.3 below) which are required for understanding these reports. The Maintenance Manual assumes access to the complete file of ENIAC drawings.
Part I of the Technical Description is intended for those who wish to have a general understanding of how the ENIAC works, without concerning themselves with the details of the circuits; it assumes no knowledge of electronics or circuit theory. Part II is intended for those who require a detailed understanding of the circuits. Its organization, to a great extent, duplicates that of Part I so as to make cross referencing between the two parts easy.
The ENIAC Operating Manual contains a complete set of instructions for operating the ENIAC. It includes very little explanatory material, and hence assumes familiarity with Part I of the Technical Description of the ENIAC. The ENIAC Maintenance Manual includes description of the various test units and procedures for testing, as well as a list of common and probable sources of trouble. It assumes a complete understanding of the circuits of ENIAC, i.e., a knowledge of both Parts I and II of the Technical Description of the ENIAC.
The Report on the ENIAC and the complete file of ENIAC drawings constitute a complete description and set of instructions for operation and maintenance of the machine. The drawings carry a number of the form PX-n-m. The following tables give the classification according to this numbering system.
TABLE 0.1
Values of Division
n
1 General
2 Test Equipment
3 Racks and Panels
4 Trays, Cables, Adaptors, and Load Boxes
5 Accumulators
6 High Speed Multiplier
7 Function Table
8 Master Programmer
9 Cycling Unit and Initiating Unit
10 Divider and Square Rooter
11 Constant Transmitter
12 Printer
13 Power Supplies
TABLE 0.2
Values of Subject
m
101-200 Wiring Diagrams
201-300 Mechanical Drawings
301-400 Report Drawings
401-500 Illustration Problem Set-Ups.
The reader of this report will be primarily interested in the types of drawings listed in the following paragraphs. A table on page 4 gives the corresponding drawing number for each unit of the ENIAC.
(1) Front Panel Drawings. These drawings show in some detail the switches, sockets, etc., for each panel of each unit. They contain the essential instructions for setting up a problem on the ENIAC.
(2) Front View drawings. There is one of these drawings for each kind of panel used in the various units of the ENIAC. These show the relative position of the trays and the locations of the various neon lights. Since these drawings show the neon lights, they can be used to check the proper operation of the various units.
(3) Block Diagrams. These drawings illustrate the logical essentials of the internal circuits of each unit. That is, resistors, condensers, and some other electrical details are not shown; but complete channels (paths of pulses or gates representing numbers or program signals) are shown in all their multiplicity. These drawings will be of interest to those who are interested in Parts I and II of the Technical Report.
(4) Cross-Section Diagrams. These drawings are electronically complete except that only one channel is shown where there is more than one. Thus, these drawings show every resistor and condenser and any other electronic elements belonging to any circuit. These drawings will be of particular interest to the maintenance personnel and to those reading Part II of the technical report.
(5) Detail Drawings. All other drawings of the ENIAC come under this heading. A complete file of drawings is available at the location of the ENIAC.
TABLE 0.3
ENIAC DRAWINGS
Unit Front Panel Front View Block Diagram Cross-Section
Initiating PX-9-302 PX-9-305 PX-9-307
Unit 9-302R
Cycling Unit PX-9-303
9-303R PX-9-304 PX-9-307
Accumulator PX-5-301 PX-5-305 PX-5-304 PX-5-115
Multiplier PX-6-302 PX-6-309 PX-6-308 PX-6-112A
6-302R 6-112B
6-303
6-303R
6-304
6-304R
Function Table PX-7-302 PX-7-305 PX-7-304 PX-7-117
7-302R 7-118
7-303
7-303R
Divider and PX-10-301 PX-10-302 PX-10-304
Square Rooter 10-301R
Constant Trans- PX-11-302 PX-11-306 PX-11-307 PX-11-116
mitter 11-302R 11-309
11-303 (C.T. & R.)
11-303R
11-304
11-304R
Printer PX-12-301 PX-12-306 PX-12-307 PX-12-115
12-301R
12-302
12-302R
12-303
12-303R
Master Pro- PX-8-301 PX-8-303 PX-8-304 PX-8-102
grammer 8-301R
8-302
8-302R
Other drawings of particular interest:
Floor Plan
(79 Kbytes)
PX-1-302
A.C. Wiring PX-1-303
Pulse Amplifier PX-4-302
and Block Diagram PX-4-301
IBM Reader and PX-11-119
plugboard PX-11-305
IBM Punch and PX-12-112
plugboard PX-12-305
Interconnection of Multiplier and Accumulators PX-6-311
Interconnection of Divider and Accumulators PX-10-307
The front view drawings and the large front panel drawings (whose numbers do not end with "R") are bound as a part of the Operator's Manual.
Included with the report is a folder containing all the drawings listed in the above table except the large front panel (see above). A complete file of drawings is available at the location of the ENIAC.
Drawings bound with the text are given with a page reference. Those contained in a separate folder are listed without a page reference. Drawings referred to but not included, in this report are marked with an asterisk. The last category of drawings are a part of the complete file of drawings at the ENIAC location.
PX-1-302 I-2 1-303 II-2 1-304* PX-2-123* PX-4-102 XI-1 4-103* 4-104a XI-3 4-104b-e* 4-109 XI-5 4-111* 4-114a-d* 4-115* 4-117* 4-119 4-301 XI-9 PX-5-105* 5-109* 5-110* 5-121* 5-131* 5-134* 5-135* 5-136* 5-137* 5-301 IV-1 5-304 5-305 IV-1 PX-6-302 V-1 6-303 V-1 6-304 V-1 6-308 6-309 V-1 6-311 V-23 PX-7-302 VII-1 7-303 VII-1 7-304 7-305 VII-1 PX-8-301 X-1 8-302 X-1 8-303 X-1 8-304 PX-9-302 II-1 9-303 III-1 9-304 III-1 9-305 II-1 9-306 I-3 9-307 PX-11-116 11-119 11-302 VIII-1 11-303 VIII-1 11-304 VIII-1 11-305 VIII-16 11-305R1 VIII-19 11-305R2 VIII-20 11-305R3 VIII-20 11-305R4 VIII-21 11-306 VIII-1 11-307 11-308 VIII-25 11-309 PX-12-112 12-114* 12-301 IX-1 12-302 IX-1 12-303 IX-1 12-305 IX-8 12-305R1 IX-9 12-305R2 IX-10 12-305R3 IX-17 12-306 IX-1 12-307