Second Standards Electronic Automatic Computer
MANUFACTURER
Electronic Computer Laboratory
Data Processing Systems Division
National Bureau of Standards
U. S. Department of Commerce
Photo, 50 K bytes
Photo by the National Bureau of Standards
APPLICATIONS
General purpose, simulation, real-time control.
PROGRAMMING AND NUMERICAL SYSTEM
Internal number system Binary
Binary digits/word 45 plus check digit
Binary digits/instruction 45 plus check digit
Instructions per word 1
Instructions decoded 16
Instructions used 16
Arithmetic system Fixed point
Instruction type Three address
Number range - (4 - 2-42) < n < (4 - 2-42)
ARITHMETIC UNIT
Incl Stor Access Exclud Stor Access
Time Microsec Microsec
Add 192 - 1,536 48
Mult 2,304 - 3,648 2,112
Div 2,304 - 3,648 2,112
Construction Diode gates, tube amplifiers, and
electrical delay lines
Rapid access word registers 3
Basic pulse repetition rate one megacycle/sec.
A four phase clock is used.
Arithmetic mode Serial
Timing Synchronous
OperationStorage and arithmetic processing are serial. Input-output external control are concurrent with arithmetic operations. In addition to the normal complement of operations, the operations of summation, accumulation, overflow check, justification, shift, and file are also included.
STORAGE
Access
Media Words Digits Microsec
Mercury Delay Line 512 24,576 48-384
There is provision for up to 4,096 words of high speed storage. In addition, the computer has provisions for the attachment of many mufti-channel magnetic tape or wire units, and. a magnetic drum. These would operate concurrently with computation operations.
INPUT
Media Speed
Keyboard Manual
Paper Tape Reader 10 char/sec
Magnetic Wire 3,500 dig/sec
Keyboard and punched paper tape reader is a Flexowriter. Alpha-numeric operation is utilized. There is provision for the attachment of a wide variety of input devices that would operate concurrently with computation. There is also a one-word addressable switch memory via a serializer unit.
OUTPUT
Media Speed
Typewriter (Flexowriter) 10 alphanum char/sec
Paper Tape Punch 60 char/sec
CRT Display Unit 2,000 words/sec
Magnetic Wire 3,500 dig/sec
There is provision for the attachment of a wide variety of output devices that would operate concurrently with computation.
CIRCUIT ELEMENTS OF ENTIRE SYSTEM
Tubes 900
Tube types 90% are 1 type
Crystal diodes 24,500
Separate cabinets 2
There are 524 tubes in the central computer and 350 in the storage unit. The central computer utilizes 21,500 crystal diodes. The central computer has two basic types of package. One type contains tube amplifiers and diode gates. The other type contains delay lines and diode gates. There are 524 tube packages and 251 delay-line packages.
CHECKING FEATURES
Fixed Odd - even parity check on storage. Optional Automatic program ,jump or print-outs are optional upon detection of a memory error. Also available for program checking are a wide variety of automonitoring operations for loading and printing out of internal storage locations and substituting new instructional addresses. Each word is checked as it is read from the memory. A real-time clock periodically initiates a storage scan which checks the entire storage.
POWER, SPACE, WEIGHT, AND SITE PREPARATION
Power, computer 12 Kw 20 KVA
Power, air cond. 35 KVA
Volume, computer 270 cu ft
Volume, air conditioner 750 cu ft
Capacity, air conditioner 18 Tons
There are two trailer vans.Van No. 1 contains the control console, input-output, computer, storage, and 12 tons of refrigeration capacity. Its internal dimensions are approximately 39 x 7 x 9 feet and weighs about 12 tons. Van No. 2 contains DC power supplies, 6 tons of refrigeration capacity, and 1,700 cubic feet of spare space. This van also has internal dimensions of 39 x 7 x 9 feet. It weighs 8 tons.
PRODUCTION RECORD
Number produced 1
Number operating 1
The DYSEAC was designed and constructed by the Electronic Computer Laboratory of the National Bureau of Standards as part of a development program under the sponsorship of the Department of Defense. It was delivered to the Signal Corps in May 1954.
RELIABILITY, OPERATING EXPERIENCE,
AND TIME AVAILABILITY
Acceptance test passed in April 1954.
ADDITIONAL FEATURES AND REMARKS
For further information on this system see
Transactions of the IRE-PGEC, Vol. EC-3. No. 1, Mar.
1954.
Transactions of the IRE-PGEC, Vol. EC-3, No. 2, June
1954.
Journal of the ACM, Vol. 1, No. 2, pp 57-81, April
1954.
Proceedings of the IRE, Vol. 41, Oct. 1953, PP
1380-1387.
Circular No. 551 National Bureau of Standards,
January 1955.
Two counter-registers are provided for program sequencing. Each counter holds a twelve-binary-digit
address. The coder may select the address in either counter as the address of the next instruction to be performed. Also, either counter-register can furnish the base number for relative addresses.
Major design emphasis was placed on versatility of control facilities and on latitude for expansion of the installation.
The versatility is achieved by (1) the concurrent input-output property, (2) a self-regulation property which allows the external environment to automatically control the pace of the internal work program, (3) an interruption property which enables the machine to handle unscheduled ,job assignments which originate externally without advance notice and must be executed as soon as possible, and (4) the preceding three properties acting in concert enable the machine to be employed as a control element in a generalized feedback loop.
For further reading and photos of these ancient beasties :
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http://ed-thelen.org/comp-hist/BRL61.html#TOC
Was this the first portable computer? 
