"STORED PROGRAM CONCEPT" Sometimes referred to as, Stored Program Control.
In the beginning “doing sums” consisted of counting sticks, pebbles,
moose droppings, and fingers & toes.
After a few thousand years of this, somebody shows up who got real tired,
real fast of this crap, and started looking for an “easier way"—not a better
way, but a way that would give him more 'ponder time.' First thing
he did was to start pondering “what's better than rocks, fingers and toes,
and moose droppings.”
At the same time there were others equally fed up, people looking for
the same thing. Some folks were successful, some were not. The upshot was
varied gadgets that, more or less were the beginnings of the first calculator.
Needless to say, the first calculators were mechanical calculators--machines.
The next improvement was to speed up the process by using electricity
with electric relays (using base-2 notation). Of course, like the
mechanical calculators, they were “hardwired” to only do a fixed set of
operations.
To make them more versatile, plug boards were introduced to alter
the machine's operation for different functions. Though an improvement,
it was still very limited functionally and slow.
The mechanical “engine” was replaced by vacuum tubes which made
the calculating engine much faster, smaller and more reliable.
By substituting the Jacquard loom's (1804) programmability for
the plug board, you have one of the first incarnation of “stored program
control.”
The great need for adequate storage was a constant, and was met
with varied solutions, albeit seemingly tortured at times— punch cards,
paper tape, etc., moose droppings...
The advent of magnetic storage: magnetic drums, magnetic core,
magnetic tape, etc., along with ever more reliable vacuum tubes filled
the gap before the silicon era.
As with all successful innovations, it was a confluence of maturing
technologies, as well as geopolitical pressures, that came together enabling
the creation of SAGE.
Computer's Units: Arithmetic-Logic Unit
Control unit
Memory
Input/Output
Bus (data path)
Sequence of Operation
1.
Fetch the next instruction from memory at the address in the program
counter.
2.
Add 1 to the program counter.
3.
Decode the instruction which commands the rest of the computer to perform
some operation. The instruction may change the address in the program counter,
permitting repetitive operations. The instruction may also change the program
counter only if some arithmetic condition is true, giving the effect of
a decision, which can be calculated to any degree of complexity by the
preceding arithmetic and logic.
The Modern Computer's evolution is as varied and complex
as any, and there is no way in Hell I and my web page can do it justice;
however, there was a seminal event in that evolution that had a profound
effect on today's modern computer, and that was "Semi-Automatic Ground
Environment," or SAGE for short.
SAGE, an air defense
shield for North America was an integration of all the relevant technologies
and inventions of the day, plus the countless technologies that SAGE
itself spawned.
I will attempt an introduction to the marvel that was
the SAGE Computer, a.k.a., "son-of-whirlwind,"
a.k.a., AN/FSQ-7/8. Given the constraints of 1950's technology, i. e.,
it weighted 250 Tons, took up 113,000 sq. ft., required 3 Megawatts to
power the 200,000 vacuum tubes that was cooled by 25 million BTU of AC,
at a cost $8 to $12 billion, and was staffed by over a thousand; the real
marvel of SAGE was that they were able
to design, develop, and field 27 functioning sites given the technology.
In the decades since SAGE,
very few could have imagined the advances that has given us today's incredible
technological society.
U.S.
Air Defense, Cold War era The World's Largest Computer The U.S. Air Force's IBM
SAGE
Computer circa 1958
Semi-Automatic
Ground
Environment SAGE stands for Semi-Automatic Ground Environment. Because, back then,
Computers were so limited
the system's only hope of working depended on the "Man in the Loop,"
hence the term Semi-Automatic.
SAGE Blockhouse/Computer: 113,000 sq ft., 250 tons, houses More than
200,000 vacuum tubes @ 3,000,000 Watts
At twenty years of
age, I worked in a SAGE facility located at Fort Lee Virginia (near Petersburg),
as an installer for Western Electric. Our job was to install all of the
Communications equipment that occupied the entire first floor. The remaining
three floors housed the computers, display consoles, administrative offices,
and crew quarters.
A lot of the information on SAGE is anecdotal and conflicting, as well
as, from my memory of 50 years ago.
Of course, as SAGE matured the numbers did change; it was operational
from ~1958 - 1983.
.
Random
Fact #104
The SAGE
building, which was aboveground, was considered "Hardened" (to the effects
of limited bomb blast). When we were installing some equipment in the first
floor telco area, I had to drill several holes in the concrete floor, 5/8"
in diameter 1 1/2" deep. I got a real insight into how hardened the building
really was; after 45 minutes and two star drills later, I was only half
way through. If I was doing it by hand I'd still be there.
After WWII and the onset of the "Cold War," there was a pressing need
for a perimeter air defense around the United States/North America. Due
to the numbers and speed of the threat, some sort of automation was seen
as the great equalizer. Automating the plotting, targeting, and the interception
of high speed enemy bombers was the strategy of the day.
The USAF enlisted MIT's help in it's design, along with several companies
for it's development, manufacture and deployment. The result was the construction
of 23* concrete-hardened "Direction Centers" across North America linked
through each's AN/FSQ-7 air-defense computer system designed to detect
Soviet bombers and guide interceptor aircraft and ground to air missiles.
Thus was born SAGE, or Semi-Automatic Ground Environment. Because, back
then, computers were so limited the system's only hope of fulfilling it's
mission depended on the "Man in the Loop," hence the term “Semi-Automatic.”
The plan was to create a North American radar perimeter of air defense
sectors, each controlled from a SAGE station with its own AN/FSQ-7/8 computer.
In 1957, the first SAGE station became operational. By 1961, the system's
23* sectors were complete. From the Canadian border to the Arctic Ocean,
three
radar networks[1] tracked aircraft, sending radar data
from the networks to the SAGE stations over standard leased telephone lines.
The SAGE stations guide interceptors and missiles to all targets.
U.S. Air Force SAGE Project Office, Air Material Command, NORAD,
Air Research & Development, Air Training Command.
MIT Lincoln Labs, SAGE Design, R & D, and integration etc.
MITRE, for system integration, R&D.
IBM, design, development, and manufacture of hardware.
Burroughs, AN/FST-2 radar data processor/network, ALRI system.
Western Electric Company (WECo) Winston Salem, for communications
infrastructure.
Bell Telephone Laboratories (BTL), SAGE effectiveness evaluation.
Western Electric Company (WECo) New York, work with USAF to
coordinate and manage the entire effort. Also, design and construction
of Direction and Combat Center buildings, and testing of the system.
System Development Corporation (SDC), (part of the RAND Corporation)
developed computer programs, training AF crews to run & maintain, etc.
In the 1950's MITRE's founders played a key role in the development
of the Semi-Automatic Ground Environment (SAGE) system, the first major
real-time, computer-based command and control system. Designed as a new
air defense system to protect the United States from long-range bombers
and other weapons, the SAGE system sent information from geographically
dispersed radars over telephone lines and gathered it at a central location
for processing by a newly designed, large-scale digital computer. As the
system evolved, SAGE broke new ground in radar, communications, computer,
information display, and computer programming technologies.
In 1958, the MITRE Corporation was formed out of the Computer System
Division of Lincoln Laboratories. Much of MITRE’s initial work focused
on the software development of SAGE’s digital computer system, radar surveillance,
communications, and weapons integration. More importantly however, MITRE
had the role of integrating many elements of the SAGE system
Some of the more impressive numbers:
It weighed 250 Tons.
Took up 113,000 sq. ft. of floor space.
Used a maxamum of ~200,000 vacuum tubes--60,000 tubes for each of two CPUs
(later, 13,000 transistors were added),
Maximum power requirements was 3,000,000 Watts.
It required two huge diesel powered air conditioners (capable of dissipating
heat from 3 Megawatts).
Architecture: duplex CPUs (Hot standby), no interrupts, CPU cycle time
6us, 75KIPS (single address). Availability was an unprecedented 99.6%.
Core memory was less than 32K bytes (8,192 x 32 bits).
150 Consoles/Workstations, housing a 20" CRT Vector Display w/Light Gun
as well as a "Typotron" alpha-numeric display tube, capable of displaying
more than 25K characters/sec.
Had much less computing power than today's $7.95 throw-away calculator
running on 2 hearing aid batteries.
In its later life it was used by FAA/ATC, and the vacuum tube spares had
to be bought from eastern block countries; it was retired in 1983.
SAGE stands for Semi-Automatic Ground Environment. Because, back then,
Computers were so limited the system's only hope of working depended on
the "Man in the Loop," hence the term Semi-Automatic.
Today it's computing power can be bested
by a faster $7.95 throw-away calculator.
Random
Fact #493
The modern-day
laptop, by any measure, is 80,000 to 1,000,000 times more powerful than
all of the computing power in the entire SAGE building! (SAGE
CPU Clock =166kHz)
Note the modern-day laptop on the kick-guard below. By any measure,
the laptop is 80,000 to 1,000,000 times more powerful than the computing
power in the entire building!
(SAGE Clock =166kHz:: i7 Intel 3.3GHz x
4 (core) = 80,000 Ratio)
Rack after Rack of Vacuum Tubes that make up a small part of
SAGE's Computer, see below.
The 'Blue Room' was off limits to all except those who had the highest
clearance. We had heard of a Major that had strayed over a security yellow
line, he was placed under arrest and sweated for 9 hours striped
to his boxers. Looking back I think the story was fake to scare the troops
straight, back over the yellow line.
Anyway, one day I went to the "Blue Room" to buzz some circuits, I was
escorted by a Air Force guard who was supposed to stay with me, but he
left. After a few minutes the room filled up, the lights went down and
some special top secret tests started up. The tests lasted for over an
hour. In the meantime it dawned on me that I had NO business in that room
and I started thinking about the Major. I couldn't remember if I had put
on clean underwear that morning or not.
With the
computer not powered and the air conditioning running full blast, you needed
to wear a jacket; with only the "filaments" turned on a T-shirt was almost
too much; and when the plates were also powered, safety barriers went up,
the heat was too intense for anyone to linger between the closely spaced
bays of hot vacuum tubes. It was estimated that if the air conditioning
were to fail, the computer would self-destruct in less than 60 seconds.
Interface wiring
Magnetic Drum Memory
SAGE AN/FSQ-7/8 Computer Maintenance Control Room .
The Blue Room's 20" vector displays were hard for the operators to read
due to the very slow refresh rate, and they were subject to ambient light
glare. To help overcome this, the scopes’ CRTs used long persistence P-7
phosphor and the viewing room was equipment with special non-glare indirect
lighting at low intensity.
Since the ceilings were twelve feet, special dropped ceilings with recessed
indirect lighting were used. The real secret to its success was a thick
honeycomb light baffle that was suspended above the scopes, they eliminated
any direct light capable of glare.
One other thing that helped, a lot of the operators were former radar
scope jockeys and they were experts at reading dim painfuly slow sweep
PPI scopes.
Honeycomb light baffle was ~6" thick with 1/4" holes
Operator having to interpret a dim scope display,
that had a refresh interval from 2 sec. to 15 sec. The long persistence
of the (P-7) phosphor helped.
Some SAGE
centers continued to operate by the FAA/ATC until 1983, more than 20 years
after its technology was obsolete and its mission rendered militarily insignificant
by the ICBM. As a final bit of irony, in the last years of its use, replacement
vacuum tubes had to be purchased from Soviet-bloc countries where they
were still being widely manufactured.
The real effectiveness
of the SAGE system has been debated over the years. Critics saying the
system would have failed to protect the US in an all out saturation bombing
raid, and that SAGE was a giant waste of money.
As to its effectiveness.
the deterrent impact of SAGE on Soviet strategic thinking made any preemptive
strike less likely.
As to it being a waste
of money, aside from the enormous technological strides that helped to
usurer in the "information age," the fact we never had to use it in anger,
ever, is proof of its worth.
.
Mapping Consoles Data from radar sites and posted ATC flight
plans are correlated using the console's image and photo-electric tube
mounted above it. .
