Constructing computer systems with minimal practical blocks can create attention-grabbing educational gadgets. Whereas some engineers would possibly make these blocks with discrete transistors, Dave Lovett of Usagi Electrical on YouTube goes much more basic. 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 accommodates 192 vacuum tubes that implement a completely practical arithmetic logic unit (ALU.) Lovett primarily based its design on a 1-bit Motorola MC14500 industrial processor. Whereas it’s extremely practical, it’s tough for admirers unfamiliar with tubes or fundamental processor design to understand what is occurring inside the array of boards.
Lovett needed to make a a lot smaller unit that may be extra accessible. The smaller UE-0.1 makes use of solely 24 tubes to create a “laptop” that’s easy sufficient to know, highly effective sufficient to do one thing attention-grabbing, and sufficiently small to slot in an individual’s fingers.
UE-0.1’s beautiful 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 huge, 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 a whole 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 knowledge (📷: Usagi Electrical, YouTube)
Given the PCB’s measurement, it actually suits within the palms of your fingers, and it’s secure 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 unfavourable 12 volts. When not holding the single-board vacuum tube laptop, the switches permit you to enter knowledge into the LU, and a vacuum fluorescent show (VFD) exhibits the standing of the instruction bus, knowledge bus, and registers.
Within the video, Lovett demonstrates soldering the digital elements, making a single repair, after which ends with an indication of the best way 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 software to know how a 1-bit laptop works.
You may obtain the Gerbers and PCB design information within the UE-0.1 GitHub repository. Keep in mind to see the one bodge (or correction) wanted to make the board practical. If you do not need to construct the UE-0.1 however nonetheless wish to expertise a 1-bit processor, the repo additionally accommodates a Logisim simulation undertaking.
