Inside a Titan missile guidance computer

This is another good read about using automated terrain mapping for cruise missile guidance systems.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;TERCOM" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;TERCOM</a><p>Notably how it fit on older computer systems with limited memory by only sampling the terrain using a predefined path which a plane will travel over with imaging sensors beforehand. For minutemen style systems with predefined targets it would work well as the terrain won’t change significantly and there will be plenty of sampling data to support a high error rate and&#x2F;or a relatively low resolution while moving at high speeds.<p>Of course it increased in quality and effectiveness over time (especially as whole topographical maps could eventually be stored, not just the path in question) but as an entirely ‘unguided’ rocket it seems to be relatively accurate for its era.

I visited the Titan Missile Museum in Tucson, AZ, where you can see the control room from which the missile could have been launched.<p>&gt; At launch, orders from the National Command Authority would have specified one of three pre-programmed targets which, for security reasons, were unknown to the crew. ... Target 2, which is classified to this day but was assumed to be within the borders of the former Soviet Union, was designated as a ground burst, suggesting that the target was a hardened facility such as a Soviet missile base. [Wikipedia]<p>While explaining this, my tour guide showed some punched tape that could be fed into a computer to program the targets. I wonder if the tape was original, and if so, how difficult it would be to decode its coordinates.

If you&#x27;re interested in the history of the Titan missile program and US nuclear program in general I recommend &quot;Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety&quot;.

The fascinating thing is that the Titan was completely inertially guided, i.e., no GPS or ground-based navigation. The high precision IMU + gyro send the computer acceleration and angular velocity and you integrate that over time to figure out where you are now. I&#x27;d think this would be very challenging and error-prone for inter-continental travel especially when the thing is planning to detonate nuclear war head. I wonder what algorithms they used. Typical code to do dead reckoning from IMU+gyro is fairly short but drifts usually is huge killer.

GM&#x2F;Delco were very diverse in manufacturing, so I&#x27;m not surprised that they also made missile components at one point. At one time they owned Frigidaire too.<p>Motorola made &quot;MTTL II&quot; which had 20xx part numbers for commercial temperature range and 21xx for industrial&#x2F;military, so these could be Signetics&#x27; variant of that. In the late 60s through the 70s semiconductor companies made <i>lots</i> of different logic families.<p>I&#x27;ve always found it a bit sad that the ultimate purpose of things like this was for destruction.

I was just thinking, imagine trying to use a modern-day smartphone for this. So much complexity how could you be sure the missile would even get off the ground. There is a big advantage to systems that engineers can mostly &quot;keep in their heads&quot;. Very few systems are that way these days.

I find it fascinating how much those grids resemble RAM chip die photos. I know the principle is different but in a sense we have just been shrinking things for over 70 years.

Of all the details, I particularly enjoyed the keying method with the half hex nuts. I&#x27;ll file that away for future projects.

I&#x27;m surprised they opted to use a passively cooled power supply.<p>I imagine it was much heavier than an equivalent active system.<p>I guess MPG doesn&#x27;t matter much on a Titan missile.

Great read! Intriguing to find out that earlier computers were using rotating drum memory systems in space flight and then delicate wiring in cores, I really hadn&#x27;t considered that. I wonder about the reliability of those systems and whether there was software compensation for that issue.

Some engineers designed this - used big part of their life for the work and the system was never used.

I love reading about avionics. New and old.

Always scares me to see this displayed for the public. Enemies watching.