Dissecting the 1968 US Military Computer: A Journey Through Time

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Source /Digital Home Text/ Zen Master

This machine has been in my eBay collection for a long time. One day, I casually glanced at my collection and suddenly found that the seller had drastically reduced the price, only $15, with a best offer option. You can’t lose with $15, you can’t get scammed for $15. Without delay, I decisively made the purchase.

According to very limited information,this machine is codenamed AN/ASX-2, and ispart of the non-cooperative identification system developed by the US military for the F4 fighter jet in 1968. The so-callednon-cooperative identification means identifying the target type directly by analyzing the characteristics of the target without using a radio transponder. Naturally, such a system has a high possibility of misjudgment. The machine being dissected isanalyzing radar echoes through spectral analysis to determine the aircraft type and judge the target category. Of course, this device is already very old, and has completely lost its confidentiality value today. In addition, in 1988, due to misjudgment, the US military shot down an Iranian passenger plane (see Iran Air Flight 655 disaster), and the US subsequently terminated the research and development of the non-cooperative identification system (of course, whether it was secretly continued is unknown). Therefore, such devices have also been completely abandoned and appeared on the internet as electronic waste.

The machine I obtained this time hasserial number 001. It is said that this set of equipmentwas only produced in a total of 6 units, and this unit is likely the first prototype developed by the US military, and it is very likely the first working machine since the US began research in 1965. Therefore, I personally feel it has considerable historical value. However, obviously, the machine can no longer operate, as several circuit boards are missing, and circuits such as the simulation front end have also been removed. Overall, it is still relatively complete. I’m sharing it to give everyone a glimpse.

The casing is gray, and nothing can be seen

This side has some writing, indicating that the machine is broken and can only be used as parts

This side has two temperature-sensitive stickers, with introductions on the back

The seller also sent a small control box, but it’s unknown if it matches the machine

Number No.001, ASSY M600663-1

The interface part originally had a fan that has long been removed

Aviation socket, it also has a coaxial interface, which is my first time seeing. It is estimated that the simulated signal from the radar enters here

Giant aviation socket

Fault indicator light, with gold plating inside

The bulb is an incandescent bulb, and there is a layer of steel mesh inside the lampshade. Indeed, high-end goods excel in detailsBelow, this is thetemperature indication label, which can be used to detect the maximum temperature during device operation. When the temperature exceeds the corresponding value on the label, the corresponding circle will turn black and will remain black permanently. This way, you can know the maximum temperature after operating the device on an aircraft for a while.

I blew it with a hairdryer for a while, and the 170-degree circle turned black

The machine’s rear hides a huge magnetic core storage module

Open a side panel, and you can see the complex bus structure inside.。。。

Close-up, this isthe circuit manually connected with specialized winding tools. Since there’s no need for printed circuits, and it’s convenient for modification and prototype production, it was very common in early computers and military devices

These two interfaces might be for debugging or programming (pure speculation)

Next, I opened another side cover… and found that quite a few boards were missing, so it seems impossible to get the machine runningHowever, fortunately, 7 circuit boards are still left

Looking from the side, there are many chips on the circuit board

From another angle

This has a 14MHz crystal oscillator, seems to be active, providing clock for the system

There’s also one that has been removed

Next, I pulled out the first board, it was simply beautiful It’s hard to imagine thatthe Americans had surface mount technology as early as 1968. Back then, Armstrong had yet to land on the moon, and Dongfanghong had not yet gone to space; most Chinese engineers had never even heard of integrated circuits

However, the reverse side.。。Uh-oh

These wires are too free-spirited.。。However, it should also be made as a prototype, just to verify functionality. The flying wires used here are something I’ve never seen before; they seem to be silver-plated wires wrapped in a very thin transparent insulating material, looking almost exposed

The chip is manufactured by General Instruments, purpose unknown. It looks quite like a cache or something. This company was later acquired by Microchip (the company that makes PIC microcontrollers).

The circuit board interface is also quite special, a hollow gold-plated cylinder

Next, I took out the second board. The circuit board is entirely made of stainless steel, embedded in an aluminum frame.This board is full of small-scale integrated circuits, likely used to implement logic functions

The reverse side is also the same free-spiritedUpon closer inspection, it is found that the power and ground connections for each chip are connected to a power bus hidden inside the board, and the other pins also use special silver-plated flying wires

The third board has not only surface mount chips but also several through-hole chips from Fairchild Semiconductor. Of course, the models are all untraceable

This board has components on both sides

In fact, there are two stainless steel circuit boards embedded in the same aluminum frame on both sides

The circuit board number is also 001

Other boards are actually quite similar, all with a lot of small-scale integrated circuitsThis one is numbered 002

The board also has a temperature label for monitoring the internal temperature of the machine

This board has clearly malfunctioned and is being debugged with flying wires

This one is the same.

All remaining circuit boards have been taken out, and you can see that each board has positioning pins at different locations on the bottom to prevent incorrect insertion

Looking from the side

Empty chassis, each socket is labeled with the corresponding module number

All circuit boards together Next, let’s look at the details. The small-scale integrated circuits used on these circuit boards are produced by Sylvania (now known for making light bulbs). This company was also one of the earliest manufacturers of integrated circuits, but it fell behind later…

It must be mentioned that Sylvania successfully developed TTL integrated circuits in 1963, making it one of the first manufacturers of TTL integrated circuits in the world (yes, even earlier than the famous Texas Instruments and the 74 series chips). The first generation TTL integrated circuits used in this machine are from Sylvania. This mini packaging is called flat pack, which was common in the 60s and widely used in military equipment.

The SGxxx in the image represents logic gates, while SFxxx represents flip-flops. According to the data, SG220 is a NAND gate, SG200 is an 8-input NAND gate, and SF130 is a 50MHz J-K flip-flop.

There’s not much to see inside the host, let’s open the cover on the back of the machine to see what’s inside

The nameplate indicates that this module is produced by Litton. This company is a well-known arms manufacturer in the US, with products including navigation systems, fire control systems, aerospace, and even produced space suits for NASA.There’s nothing valuable written on the nameplate, but according to the data, this is a 32KB magnetic core storage module

After removing it

Looking at it alone, it says bad memory, indicating that the memory module is also broken 23333

The entire module is completely wrapped in metal and has a seal

The seal reads Litton Company/Navigation and Control Division, last date July 12, 1972

I originally didn’t want to break the seal, but to see what it looked like inside, I still painfully disassembled it…After removing the side, I saw a pile of magnetic core storage boards stacked together

From another angle The lid on top should have more stuff, let’s continue disassemblingAs soon as I opened the lid, a golden light flashed.。。I’m going blind.。。。

All golden chips are arranged neatly….I must say, so far, this is the most beautiful circuit I have ever seen

Taking it down, this is the front side

The reverse side has another layer, with two boards attached to a steel plate on either sideFront circuit board number 001

Fairchild’s chips

These are ceramic resistors

Resistors

The white ones are Motorola chips

SN5400, the famous TI appears! This is a flat pack packaged 74 series TTL chip, produced in the fourth week of 1968. 54 indicates military grade chips, and 5400 is naturally the famous 4-NAND gate It is said that in 1968, a chip like this was worth $20, so the entire system must have been quite expensive

The other side of the module also has a similar circuit boardThe front and previous ones are exactly the same, likely the front circuit for magnetic core read and write

Flying wires are still unavoidable

These two boards together, this is the reverse side, different functions, and component arrangements are also different

The front side, seemingly the same

Let’s check the serial numbers, one is 01, the other is 02. The serial numbers are printed on, the Americans really put in effort.。。

Close-up, modern 74HC chips and 50-year-old 54 chips are appearing together It’s surprising that despite so much time passing, the pitch of the surface mount SO package has remained unchanged for 50 years. One cannot help but admire the foresight of the Americans in establishing standards. Looking at us, many standards are constantly changing, making it difficult to sustain.

After removing the board, the module, made of stainless steelwith gold-plated interfaces

Upon further disassembly, a pile of magnetic cores can be seen On top is a diode board, and below are all magnetic core boards. Unfortunately, they are soldered together and cannot be disassembled without damage, so I won’t take them apart Diode array A bunch of wiringHere’s a small board, the chips on it are simply… From left to right, they come from National Semiconductor (NS), Texas Instruments (TI), Motorola, HELIPOT (a resistor manufacturer), and on the far right is Fairchild.Finally, here are a few overall pictures of the module. It’s so beautiful that I can’t help but share more picturesThus, the disassembly is completedFinally, here’s a picture that can serve as a desktop background

-End-

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