Linux/4004: booting Linux on Intel 4004 for fun, art, and no profit

15 MHz m68030 with a 16 bit memory bus and 10 megabytes of RAM -- A Mac LC II, by any chance? :)

> towards the late '80s and early '90s

By the late 1960s, really. It would probably be possible to port Linux to the Model 65 [1]; might even be easy since GCC can already target the instruction set. The MMU is sufficient. Maybe a tight squeeze with the max of 2 MB of fast core. Would be in a similar ballpark, a bit slower, to that 68030 machine.

Full virtualization, and hardware enforced memory and IO boundaries, were invented early on, too. It took a while for such features to trickle down to mini- and then micro- computers. And then much longer for popular software to take advantage.

[1] https://en.wikipedia.org/wiki/IBM_System/360_Model_65

That's basically the concept of Turing Completeness. Any Turing complete system can run anything. It may be very slow, but it will run. ChatGPT could run on a 4004, all you need is time.

I don’t know if this was a thing in America, but in USSR in the 70s and 80s it was very popular to play chess-by-correspondence. You would literally snail-mail letters back-and-forth with your move. Games would last months or years. It added an extra challenge to chess because by the time you got a response, you might have forgotten what strategy you had had.

This project is basically Linux-by-correspondence. The challenge is here too. By the time the command produces an output, you might have forgotten why you ran it.

Fixed the typo. Thanks

Make it out of transistors and i'll port my MIPS emulator to it :)

While it boots, you can look at LEDs and map them to kernel function easily by running “nm” on vmlinux.

Also, when in user space, you can tell between the main binary (way below 0x01000000) and shared libraries (loaded high near 0x77000000)

Sorry for the nitpick, but the laptop in the video looks like Windows 2000

Windows 2000

For the video, i wanted a laptop with a real serial port (no usb). This one fit the bill and was $20 on eBay. Windows 2000 is the prettiest windows IMHO, so that’s what I installed for the demo video.

There's the Turing award, which is an equivalent prize for computing. Could add an acknowledgement for strange and unusual applications of computer science.

Probably closest would be the Ig: https://en.wikipedia.org/wiki/Ig_Nobel_Prize

not that I found. And it makes sense since without MHz-fast 4002 and 4289, it is useless. Plus, swinging a bus from -15V to 0V at MHz speeds will take quite some drive current.

That is before many optimizations. Current boot time (on a real 4004 at 790KHz) is ~4.5 days. At 740 it would thus be 4.8 days

Very impressive work, but most of the work has been necessary because Intel 4004 was not really the first microprocessor, this was just BS propaganda used by Intel to push back by one year the date of the launch of the first microprocessor, to 1971.

The first true (civilian) microprocessor was Intel 8008, in 1972.

Intel 8008 was a monolithic implementation, i.e. in a single PMOS integrated circuit, of the processor of Datapoint 2200, therefore it deserves the name "microprocessor".

The processor of Datapoint 2200 had an ugly architecture, but there is no doubt that it was a general-purpose CPU and traces of its ISA remain present in the latest Intel and AMD CPUs.

On the other hand, the set of chips that included Intel 4004 was not intended for the implementation of a general-purpose computer, but it was intended just for the implementation of a classic desktop calculator, not even a programmable desktop calculator.

This is the reason for the many quirks of Intel 4004, e.g. the lack of instructions for the logic operations, and many others that have increased the amount of work required for implementing a MIPS emulator suitable for running Linux.

Even if Intel 4004 was intended for a restricted application, after Intel has offered to sell it to anyone, there have been many who have succeeded to use it in various creative ways for implementing microcontrollers for the automation of diverse industrial processes, saving some money or some space over a TTL implementation.

In the early days of the electronics industry it was very normal to find ways to use integrated circuits for purposes very different from those for which the circuits had been designed. Such applications do not make Intel 4004 a true microcontroller or microprocessor. Very soon many other companies, and later also Intel, have begun to produce true microcontrollers, designed for this purpose, either 4-bit or 8-bit MCUs, then Intel 4004 has no longer been used for new designs.

I didn't know the guy but he clearly knows what he's doing, it's unbelievably entertaining to read the details of achieving an impossible task with the most underpowered tool possible.

I mean, it's fun and interesting bullshit that cheats a lot. I'm sure that you could emulate a MIPS using a one-bit processor like the MC14500[0] with enough supporting hardware, real or virtual. Looking forward to it, Dimitry.

[0] https://en.wikipedia.org/wiki/Motorola_MC14500B

It's not really the addressing modes, but the instruction format. Immediate values on RISC-V are not stored contiguously on certain RISC-V instructions.

On all MIPS instructions, the bits for a immediate add, load constant, branch, etc value are always stored in order.

On RISC-V, the bits are (sometimes) jumbled around. For example, on a unconditional branch, the bits for the destination offset are stored in the order of bit 19, bits 9-0, bit 10, bits 18-11. In hardware, reordering that is free, you just run your wires the right way to decode it. In software, you have to do a ton of bit manipulation to fix it up.

The reason RISC-V does that is to simplify the hardware design.

Probably nothing unless you want to emulate it on severely underpowered hardware.

it was

Windows ran on a similar MIPS machine (Microsoft jazz). The issue is emulating scsi. I think I’d need a lot more rom space to do that. Scam is messy and hard.

The alternative is to find the Windows MIPS DDK and build a paravirtualized disk driver for it like I did for Linux. That would make it more doable.

I have two visions of this.

One, it reminds me of that "worlds longest song" or somesuch thing, where they play a note every 10 years.

The other is just a picture of someone, asleep at their desk, a pile of calendars with days checked off tossed to the side, random unwashed mugs and such all dimly lit by a desk lamp and see the `$ make linux` finally return to an new, unassuming `$` prompt. Like Neo in the Matrix.

I wonder of you can calculate when it will finish by counting the instructions and then pin the date it will finish and stream the completion.

Ars Longa, Vita Brevis

I’d assume you’d have at least a few bit flips occur in the process.