Looking At Standard-Cell Design In The Pentium Processor

Die photo of the Intel Pentium processor with standard cells highlighted in red. The edges of the chip suffered some damage when I removed the metal layers. (Credit: Ken Shirriff)
Die photo of the Intel Pentium processor with standard cells highlighted in red. The edges of the chip suffered some damage when I removed the metal layers. (Credit: Ken Shirriff)

Whereas the CPUs and similar ASICs of the 1970s had their transistors laid out manually, with the move from LSI to VLSI, it became necessary to optimize the process of laying out the transistors and the metal interconnects between them. This resulted in the development of standard-cells: effectively batches of transistors with each a specific function that could be chained together. First simple and then more advanced auto-routing algorithms handled the placement and routing of these standard elements, leading to dies with easily recognizable structures under an optical microscope. Case in point an original (P54C) Intel Pentium, which [Ken Shirriff] took an in-depth look at.

Using a by now almost unimaginably large 600 nm process, the individual elements of these standard cells including their PMOS and NMOS components within the BiCMOS process can be readily identified and their structure reverse-engineered. What’s interesting about BiCMOS compared to CMOS is that the former allows for the use of bipolar junction transistors, which offer a range of speed, gain and output impedance advantages that are beneficial for some part of a CPU compared to CMOS. Over time BiCMOS’ advantages became less pronounced and was eventually abandoned.

All in all, this glimpse at the internals of a Pentium processor provides a fascinating snapshot of high-end Intel semiconductor prowess in the early 1990s.

(Top image: A D flip-flop in the Pentium. Credit: [Ken Shirriff] )

Weird Al’s Monster Battlestation Is Now Just A Reasonably Fast PC

Wanna be hackers? Code crackers? Slackers. If the vintage computing community ever chooses an official anthem, count my vote for It’s All About The Pentiums by “Weird Al” Yankovic. More than twenty years after its release, this track and its music video (with Drew Carey!) are still just as enjoyable as they ever were, with the track’s stinging barbs and computing references somehow only improving over time.

In the track, Weird Al takes on the role of ‘king of the nerds’ with his rock star-esque portrayal of a nameless personal computing legend, someone who de-fragments their hard drive “for thrills” and upgrades their system “at least twice a day”. The lyrics are a real goldmine for anyone that is a fan of 1990s computing, but what stands out to me is the absurd hardware that Weird Al’s character claims to own.

Absurd by 1990s standards, maybe. Not so much anymore. Even with the ongoing chip shortage and other logistic shortfalls, everyone now has the opportunity to start cruising cyberspace like Weird Al and truly become the “king of the spreadsheets”. However, would it have even been possible to reach these lofty computing goals at the time of the parody’s release? Let’s check out both of these threads.

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Modern Linux Runs On Ancient Toshiba

While Microsoft no longer supports those of its operating systems that were in heavy use into the early 2000s, support for old hardware is not typically something that you will have to worry about if you run Linux on your machines. Sure, there will be driver issues from time to time, and you might have to do some things by hand, but if you’re using legacy hardware you’ll want a Linux distribution of some sort. Especially if you’re running it on one of the first laptops to ever feature a Pentium processor of any kind.

This is a Toshiba T4900CT which [MingcongBai] has been able to spruce up by installing a simplified version of the AOSC OS Linux distribution. The distribution is known for its simplified user interface, and this particular one runs a “Retro” command-line-only version. Upon startup (which takes over two minutes), the user can view the hardware and software specs: Linux kernel 4.19.67 (released within the past year) on a 75 MHz Intel processor.

Getting old equipment to work, even if the software is available, is a challenge and this one stands out for the historical noteworthiness of the laptop. We didn’t see it connect to the Internet, but if it ever does we still keep Retro Hackaday up specifically for situations like this.

Sushi Roll Helps Inspect Your CPU Internals

[Gamozolabs’] post about Sushi Roll — a research kernel for monitoring Intel CPU internals — is pretty long. While we were disappointed at the end that the kernel’s source is not exactly available due to “sensitive features”, we were so impressed with the description of the modern x86 architecture and some of the work done with Sushi Roll, that we just had to post it. If the post gets you wanting to actually try some of this, you can check out another [Gamozolabs] creation, Orange Slice.

While you probably know that a modern Intel CPU bears little resemblance to the old 8086 processor it emulates, it is surprising, sometimes, to realize just how far it has gone. The very first thing the CPU does is to break your instruction up into microoperations. The execution engine uses some sophisticated techniques for register renaming and scheduling that allow you to run instructions out of order and to run more than one instruction per clock cycle.

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Intel Edison on a box

Running Golang On The Intel Edison

While most embedded development is still done in C and/or assembly, some people are working with more modern languages. The team over at Gobot has successfully managed to get Go running on the Intel Edison.

The Go programming language, which has been around for about five years, compiles to machine code like C. It has a number of modern features including concurrency, garbage collection, and packages.

We’ve looked at the Edison on Hackaday before, and even took a detailed look at the hardware. It features a Quark SoC, Bluetooth, and WiFi, which makes it well suited for connected devices.

Getting Go to work on the Edison hardware wasn’t particularly difficult, since it supports the Pentium instruction set and MMX. However, a library was needed to interface with the Edison’s peripherals. The Gobot team whipped up gobot-intel-iot, which makes it easy to work with GPIO, I2C, and PWM.

After the break, the team demos PWM on the Edison using Go.
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Old Laptops, Modems, And The Hackaday Retro Edition

We haven’t been getting very many submissions of extremely old computers loading up the Hackaday Retro Edition in a while. For shame. Thankfully, [alnwlsn] is here to pick up the slack from the rest of you with his latest accomplishment, getting two old laptops on the Internet with some old telecom equipment.

The first is a Toshiba from about 1995, Pentium processor, 12 MB of RAM, and a 10 GB (!) hard drive. [aln] had a PCMICA modem sitting around, and with Windows 95 and IE 5.5, he was able to slowly connect.

Pentium class machines are okay, but the next one – a Zenith Data Systems laptop from about 1987 – is awesome. 80C88 CPU, two 720k floppy drives, and the exact amount of RAM in that quote falsely attributed to [Bill Gates]. [alnwlsn] is connecting with a 28.8k modem, but the serial port only supports up to 9600. It’s a computer so old, even the retro edition’s main page times out. The about page, though, loaded fine.

[alnwlsn] used a modem with both of these laptops, but he doesn’t have dial-up or even a landline. This forced him to make his own line simulator that requires plugging in the phone line at the right time, manually ringing a modem connected to another computer, and letting PPP take it from there. It’s a crude circuit, but it works. slow, but it works. Video below.

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Repairing A Mill That Cost As Much As A Car

miters

Years ago, someone at the bio-instrumentation lab at MIT needed to change a CMOS battery in the controller for a three axis mill. This reset the machine’s BIOS and was widely regarded as a bad move. The mill sat in the lab for a few years before  Prof. [Ian Hunter] donated it to MITERS – the student shop at MIT. And so the task of repairing a machine that cost as much as a car fell upon a plucky group of students.

The machine – a  Dyna-Myte 1007 has a 10″x7″x10″ work area, pneumatic tool changers and carousel, and the working for a fourth axis. It is. however, driven by an ancient Pentium computer running DOS with all the fun of ISA slots and IRQs that entails.

The MITERS began their repair by digging around in the software configuration, finding the axis drive is controlled via IRQ 3, which was currently occupied by COM 2. Changing that in the BIOS let the computer control the axes and, with a few solenoids and an air compressor, the tool carousel also worked.

With a bit of digging around, the MITERS also got the spindle working, giving them a very awesome and very expensive CNC milling machine for free. Even though the computer could be replaced with a $35 Raspberry Pi, we really have to admire the MITERS for fixing what they already had; it’s a cheaper and much, much faster way to get their new toy up and running.

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