Constructing computer systems with minimal purposeful blocks can create fascinating tutorial units. Whereas some engineers may make these blocks with discrete transistors, Dave Lovett of Usagi Electrical on YouTube goes much more elementary. UE-0.1 is a one-bit single-board laptop constructed with 24 vacuum tubes!
UE-1 in background, UE-0.1 in Lovett’s hand (📷: Usagi Electrical, YouTube)
The UE-0.1 is a scaled-down model of the UE-1. The complete-sized UE-1 suits on a wall and incorporates 192 vacuum tubes that implement a totally purposeful arithmetic logic unit (ALU.) Lovett primarily based its design on a 1-bit Motorola MC14500 industrial processor. Whereas it’s extremely purposeful, it’s tough for admirers unfamiliar with tubes or fundamental processor design to know what is occurring throughout the array of boards.
Lovett needed to make a a lot smaller unit that will be extra accessible. The smaller UE-0.1 makes use of solely 24 tubes to create a “laptop” that’s easy sufficient to grasp, highly effective sufficient to do one thing fascinating, and sufficiently small to slot in an individual’s arms.
UE-0.1’s attractive PCB earlier than including elements (📷: Usagi Electrical, YouTube)
UE-0.1’s PCB measures 267 by 221 millimeters and is a contemporary design. Lovett gave the traces a visually hanging type by making them 1 millimeter broad, separated by 2.54 millimeters, and curved. By having the boards fabricated with out solder masks (or silkscreen), the mixed effort leads to a gorgeous-looking design.
In contrast to its bigger cousin, the 24-tube design doesn’t implement an entire ALU. As an alternative, it solely has a logic unit (LU) constructed from NOR gates. Most of UE-0.1’s blocks include solely NOR gates as a result of Lovett says these are very simple to implement with vacuum tubes.
VFD displaying information (📷: Usagi Electrical, YouTube)
Given the PCB’s dimension, it actually suits within the palms of your arms, and it’s protected to carry! In contrast to many vacuum tube initiatives, UE-0.1 runs at comparatively low voltages. There are solely two provides: optimistic 24 volts and destructive 12 volts. When not holding the single-board vacuum tube laptop, the switches will let you enter information into the LU, and a vacuum fluorescent show (VFD) exhibits the standing of the instruction bus, information bus, and registers.
Within the video, Lovett demonstrates soldering the digital elements, making a single repair, after which ends with an indication of tips on how to make UE-0.1 calculate 1 + 1! Whereas even Lovett admits this isn’t a full-fledged laptop, it’s undoubtedly a wonderful coach device to grasp how a 1-bit laptop works.
You may obtain the Gerbers and PCB design recordsdata within the UE-0.1 GitHub repository. Keep in mind to see the one bodge (or correction) wanted to make the board purposeful. If you don’t want to construct the UE-0.1 however nonetheless wish to expertise a 1-bit processor, the repo additionally incorporates a Logisim simulation challenge.