Ken Shirriff

@righto.com

6187 Followers 296 Following

Computer history. Reverse-engineering old chips. Restored Apollo Guidance Computer, Alto. Ex-Google, Sun, Msft. So-called boffin.

This is a black-and-white exploded drawing, with many labels. To summarize, the boards were inserted in the box vertically, tightly packed front-to-back.
Two circuit boards. The bottom one is the interface board seen earlier. The top board is a standard 4 Pi board. It looks very similar with five rows of flat-pack integrated circuits, a metal frame, two green connectors, and thumbscrews. But the bottom board is one inch wider and the connector has 120 pins instead of 98.
The second board, same as in the first message. It has standard DIP (dual-inline package) integrated circuits. Most of them are white ceramic with gold lids, interspersed with regular black integrated circuits. The chips are mostly arranged in three rows, but three integrated circuits are arranged horizontally.
The other side of the network board; it looks just like the previous photo with four large golden chips, a square golden hybrid module, and rows of tiny black chips. It has a 120-pin green connector at the bottom, but much of the plastic is broken, as often happens with these connectors.
Two rectangular aluminum-alloy boxes, each about 10″ × 7.5″ × 22.5″. Each box has two rectangular handles on the front, as well as multiple round military-style connectors. Each box is marked "Caution: weight over 45 pounds."
A schematic showing exclusive-or gates, four multiplexers, and a 5-input NOR gate.
A diagram from the 8087 patent showing the circuitry that surrounds the adder. One value to add comes from the fraction bus, while the other value comes from a register called the B register. The output from the adder can be shifted by the sum shifter. The skip shifter holds the multiplicand or square root value.
A close-up of the die showing the silicon and polysilicon. The photo has complex patterns with silicon blobs of various shapes with polysilicon lines in various directions, mostly horizontal and vertical. Many small circles are visible; these are contacts that connect the silicon to the metal layer shown earlier. The white squares are similar contacts between the polysilicon wiring and the metal layer.
A close-up die photo. It shows white metal lines over a brownish background. Most of the metal lines are tightly packed and roughly horizontal, providing connections within the adder. At the sides, vertical metal lines provide signals to the adder and other circuits.
A die photo of the 8087 chip, with functional blocks labeled. The die has complex patterns with roughly rectangular shapes. Around the edges, thin bond wires connect the die to the chip's 40 external pins. In the bottom center, the adder is highlighted. It is a tall, thin rectangle in the middle of the "fraction datapath". Above it is the exponent datapath.
A vintage ad. In the center are five tube modules. Each one has a vacuum tube and components surrounded by a U-shaped frame. The modules are vaguely finger-shaped, so the ad has the slogan "Fingers you can count on". In the background, a faint hand is counting on the fingers of another hand. At the bottom is a small photo of the IBM 604 system with a man standing next to it. The door on the system is open, showing the wiring inside. For some reason, there is an atom symbol (an atomic whirl) next to the modules. The text says: These are electronic "fingers"... the compact and rugged pluggable units in IBM Electronic Business Machines. Their high-speed counting capacity and amazing accuracy meet the most exacting accounting and calculating requirements of business, industry, and engineering. These "fingers"...backed by IBM service, research, and development...are helping to fulfill production demands with economy of time, materials, and cost.
A thyratron tube. It is a glass cylinder with a peak at the top and black deposits near the top. It has seven pins at the bottom. Metal structures are inside it. It is labeled Mullard 2D21 Made in Gt. Britain.
A video of the tube module controlling a light bulb. The module is mounted in a box with a bunch of wires coming out. Wires go to power supplies, a household light bulb, and two buttons. When I push the first button, the light illuminates. When I push the second button, the light turns off.
Black and white photo of the IBM 604 Electronic Calculating Punch behind a Type 521 Card Reader/Punch. The IBM 604 is about the size of two refrigerators. It's a dark gray box with art deco-ish chrome trim. The Card Reader/Punch is slightly smaller but the same style. It has a hopper on top for inserting a stack of punch cards.
A close-up of the 8087's microcode ROM, showing 77 transistors. The image consists of vertical lines (polysilicon) crossing a complex pattern of pinkish regions (doped silicon) in irregular horizontal and vertical stripes. A transistor is formed where a vertical polysilicon line crosses a horizontal stripe of doped silicon.
The die of the 8087 chip under the microscope. The chip is very complicated with patterned regions in purplish-brown. The regions are generally rectangular with the transistors forming various textures. Around the edges, black wires connect pads on the chip to the external pins. Key functional blocks are labeled including the microcode ROM, microcode engine, exponent datapath, and fraction datapath.
The 8087 chip is a black rectangle with 40 metal pins along its long sides. This package is known as a DIP (dual inline package). Unlike modern chips, this chip is a ceramic package. Text on the chip includes "D8087-1" "Intel copyright 1980 1984"/
The IBM AP-101SL Spacelab computer with the lid removed, showing the circuit boards inside. The circuit boards are much larger than the boards in the original computer. The boards have small "flat-pack" ICs, which can be packed much more tightly, and the boards have ICs on both sides. Thus, the new computer was much denser and more powerful than the old one.
The back of the circuit board. It has soldered holes in a grid pattern, with circuit board traces running between the holes. A few thin yellow wires are attached to the board, connecting various pins.
A circuit board with the function of each chip labeled: multiplexers, ALU, register, inverter, or NAND gate.
Three circuit boards that formed the 32-bit arithmetic/logic unit in the Spacelab computer. Each board is crammed with chips and has a blue connector at the bottom. The first board has two of the larger ALU chips, while the other boards each have three, so there are eight ALU chips in total. The boards have a metal frame and metal bars run under the chips; this provided convection cooling for the computer.
The computer is a shiny metal box, roughly the size of a toaster oven. It has two handles on the front, as well as six round military-style connectors. The computer is labeled "cimsa", the manufacturer. I took the top of the computer, so you can see the 36 circuit boards inside. The photo shows a close-up of one of the circuit boards. The board contains 28 rectangular integrated circuits. Three of the integrated circuits are much larger than the others.
The Angle Computer contains dozens of gears of various sizes and metals. Thicker brass-colored differential gear mechanisms are sandwiched between gears. A cylindrical motor is visible in the lower right . A thick, colorful wiring bundle is at the back.
The back view of the Angle Computer shows more gears and a lot of terminal strips for the wiring. Numerous cylindrical motors, synchros, and control transformers are visible.
A close-up of the Angle Computer, showing gears and mechanisms. Various components are labeled, but it's too hard to describe in detail. To summarize, the star pointer is moved by a U-shaped arm that rotates around the declination axis. The mechanism also rotates around the polar axis. A latitude arm moves up and down, corresponding to the aircraft's latitude. Large gears on the right drive the mechanism.
The Astro Tracker is a round unit that looks a bit like a UFO. It has a clear bubble at the top and two handles on the sides. It has several round military-style connectors. The unit is black, with some chips in the paint showing the metal underneath. It has some labels on the front, including one that says "Tracker, Astro".
The Angle Computer is a complicated electromechanical system with gears, motors, and bundles of wires. It has a grey metal shell that includes a half sphere. Inside this sphere, arms move a star pointer to indicate the position of a star. Other gears and mechanisms read out the position.
One of the CPU boards from the AP-101S, specifically the CPU1 board. It is full of flat-pack integrated circuits in a 10 by 18 grid; some are black and some are white. If you look closely, you can see "bodge wires" that correct errors on the board. The nine large ICs in the center are four-bit arithmetic-logic unit chips (74F181) for the 36-bit "fraction" ALU. Much of the logic uses FAST (Fairchild Advanced Schottky Technology) TTL chips for improved performance. The board is covered with brown conformal coating to protect it from the environment.
The Space Shuttle I/O Processor (IOP, left) and AP-101B computer (right). Each is a 60-pound gray metal box with round military-style connectors on the front and black U-shaped handles. Photo courtesy of RR Auction.
The arithmetic and control subassembly of a TC computer, configured for a tactical missile. The board is a semicircle with about 100 thumbnail-sized integrated circuits mounted on it. From Electronics, March 6, 1967.
The TC-2 computer was used on the A-7 Corsair II aircraft. The computer is a gray box, a bit under a cubic foot. It has round military-style connectors on the front, as well as a black fan. It has stencilled text: "Caution: Weight over 60 pounds", "Grip Area Underneath". The fan has a red warning label: "No step. No lift. High temperature." Photo courtesy of Alex1970-14.
A die photo of the Jump PLA. The left side is a large grid of transistors, with some transistors missing. It acts as a ROM that holds the jump addresses, and outputs an 11-bit address at the top. The right sigde of the image is the decoder. It takes the jump number, decodes it, and activates a horizontal. At the upper right, some logic gates are the "operation logic", determining what operation is being performed . This handles the special "jump 0".
A close-up of the instruction decoding PLA. It shows part of the grid of transistors. One transistor is highlighted in green, while a red highlight shows where a transistor is missing. At the top, pull-up transistors pull the outputs high by default.
A die photo of the 8087 chip, with the main functional blocks labeled. The chip is a tan rectangle with complex patterns in dark brown. Many of the patterned regions are textured rectangles. One of the largest rectangles is the microcode ROM in the middle. The bottom half of the chip is the datapath, performing operations on floating-point numbers. The instruction decoding happens in the upper left. Around the edges of the chip, bond wires connect the chip to the 40 external pins, but the pins are not visible, just short segments of the bond wires.
A close-up of the ALU control circuitry in the 8086. In this die image, I removed the metal layer to show the underlying silicon and polysilicon. I've labeled the temporary register latch, the XI multiplexer, the operation PLA, the operation latch, the lookup table PLA and miscellaneous decoding circuitry.
A die photo of the 8086 microprocessor. The image shows a tan square with complex patterns of beige and dark lines showing the circuitry. Thicker light lines distribute power across the chip while black bond wires are attached around the edges. Various regions with different patterns are labeled with their function including a large rectangular region in the lower right that holds the microcode and the 16-bit ALU in the lower left. The ALU Control circuit at the bottom is highlighted.
A close-up of the 8087 die. There are white horizontal and vertical lines of various widths, the chip's metal wiring. Text in metal is also visible: "8087", "i/IL", and a maskwork/copyright marking: "(m) (c) intel 1980".
A block diagram from the patent. It shows the top-of-stack pointer (TOS) with controls to increment and decrement when pushing or popping values. A subtractor circuit computes offsets into the stack. A multiplexer selects either the top-of-stack or the offset value. A decoder selects one entry in the stack based on this value. The value in the stack is split across the fraction bus, exponent bus, and tag bus.
A diagram showing two inverters in a loop. On the left, the first inverter has a 0 and the second has a 1. On the right, the values are switched. Thus, the circuit can hold a 0 or a 1.
The registers in the 8087 chip form a tall, skinny rectangle. The storage cells are arranged in eight columns for the eight registers. At the top are two tag bits, then 16 bits for sign and exponent, and then 64 bits for the fraction part of the number. The image zooms in on an 8 by 8 block of storage cells. For this image, I removed the metal layer with acid, so you can see the silicon structures underneath. The silicon appears pinkish-tan.
A photo of the 8087 die under a microscope. The die is rectangular, with complex patterns in purplish-brown. The patterns consist of rectangular regions, striped regions in the bottom half of the chip, and other more irregular regions. At the right, two regions are highlighted in red: the registers and the stack control circuitry. Around the edges of the die, you can see the hair-thin bond wires that connect the chip to its 40 external pins. The complex patterns on the die are formed by its metal wiring, as well as the polysilicon and silicon underneath. The bottom half of the chip is the "datapath", the circuitry that performs calculations on 80-bit floating point values. At the left of the datapath, a constant ROM holds important constants such as π. At the right are the eight registers that form the stack, along with the stack control circuitry. The chip's instructions are defined by the large rectangular microcode ROM in the middle.
A standard-cell inverter as it appears on the die, along with a diagram explaining the layout. The die image has green lines of polysilicon over grayish rectangles of silicon that look a bit like Lego bricks. The diagram shows how the inverter is constructed from a PMOS transistor and an NMOS transistor
A close-up of two columns of standard cell logic. I dissolved the metal layers with acid for this photo, so you can see the silicon. Each transistor has a dark outline around it. The transistors are all in columns except for one lone transistor between the columns; it is marked with a red arrow. The photo also has a few large greenish regions. These are areas where I couldn't remove the oxide layer completely, so they can be ignored.
A close-up of two standard cells in the 386. The cells are outlined with green boxes. The photo looks like dark brown horizontal and vertical lines on a tan background, with large and small circles in the boxes. The photo is mostly incomprehensible because of the density of wiring in the 386, but what it shows is a layer of horizontal wiring and a layer of vertical wiring (the stripes between the dark lines). The larger circles connect the two metal layers, while the small dots connect the metal layer to the silicon or polysilicon underneath,
A close-up of standard cell logic in the 386 processor. The circuitry appears as four irregular dark bands, with horizontal and vertical connections in the regions between the dark bands.
A die photo of the 386 processor. It is a square with complicated patterns on top. Under the microscope, the circuits appear in dark purple. Parts of the chip have been marked with boxes: these are standard cell circuits and have a distinctive striped appearance.
A Pips problem with the solution. It has numbers in the cells, corresponding to dominoes.
The same three-by-three grid of squares with four dominoes below it. Two squares are labeled with "8", indicating that the numbers in that region must sum to eight. Another square is labeled "<5", indicating that the number in that square must be less than 5. The three bottom squares are labeled with an equals sign, indicating that the three numbers must be the same. The upper-right square is missing so there are 8 squares in total, able to hold four dominoes.
A three-by-three grid of squares with four dominoes below it. Two squares are labeled with "8", indicating that the numbers in that region must sum to eight. Another square is labeled "<5", indicating that the number in that square must be less than 5. The three bottom squares are labeled with an equals sign, indicating that the three numbers must be the same. The upper-right square is missing so there are 8 squares in total, able to hold four dominoes.
A hammer assemblly with the coil attached. It is an irregularly-shaped metal unit that is kind of grungy. It looks vaguely like an elephant with a long, straight trunk forming the part that hits the paper.
The back side of the printer after removing the cover, paper guides, and cooling air hose. The hammer unit is a big gray unit in the middle. On either side, metal guide rails have been attached to the printer and stick out horizontally.
The print chain unit, about 14 inches wide and maybe an inch high. A chain is visible at the front with a sequence of raised charcters in reverse.
The IBM 1403 line printer is a large unit on a stand, printing on green-bar paper that feeds in at the bottom. The printer is dark gray with a clear plastic cover over the printer and a blue panel at the left with a few control buttons. Behind the printer, three 729 tape drives are visible, each about the size of a refrigerator. The IBM 1401 computer is partially visible at the right, about the size of two refrigerators. It has a control panel with lights, switches, and knobs.
A complex die photo with many rectangular and irregular regions. I've applied a color gradient making the photo look slightly rainbow-ish, purple and blue in the top and red and yellow at the bottom. The image has a Chipwise logo on it.
A rug representing the Intel Pentium processor. The style of this rug is very different from the previous one. It is a Navajo rug with a complex pattern with muted reds, pinks and blues. The pattern consists of various vertical and horizontal rectangles with stripes. Around the border are small alternating black and colored rectangles. The weaving is mounted in a wooden frame and hanging on the museum wall.
An image of the rug next to a photograph of the 555 chip's die. Both are white patterns on a black background. They match closely, but there are a few changes. The wiring at the top has been simplified. The part number at the bottom has been removed.
An integrated circuit in a metal can, sitting on top of a penny. I cut the top off the metal can, revealing the silicon die inside. The silicon die itself is a bit bigger than Lincoln's nose. Eight tiny bond wires connect the silicon die to the eight pins around the periphery of the metal can.
A Navajo weaving hanging on a wall. The pattern appears abstract: thick white lines in varying directions on a black background. There are some reddish-orange diamonds near the edges, as well as a few thin outlined rectangles. There are three larger squares with a double-H pattern inside. Overall, the pattern looks a bit like an aerial view of roads in a strange ancient city. Thanks to First American Art Magazine for this photo.
Text from the journal Science. I've highlighted the formula Cr2Gr2Te6; the rest of the text is not particularly relevant, discussing thin magnetic materials.
Another close-up die photo. This one shows more circuitry than the previous ones. It shows two standard latch circuits, along with two special sense-amplifier latch circuits that reduce metastability. The sense-amp latch circuits are larger than the regular latches. The diagram also shows protection diodes and guard rings. At the bottom, the large square bond pad is where the bond wire is attached.