Pencilbox, by E&L Instruments, is a Logic Designer aimed at allowing a user to quickly build a simple logic circuit to interface to a microprocessor.
It can fulfill modest requirements for the design and study of gates, counters, multiplexers and can even interface directly to a microprocessor. (LD-1 Pencilbox User Manual, introduction)
The Pencilbox runs off either 4x “C” Size batteries, or a 5V main PSU. The kit contains the following features:
- 8 LED Logic Indicators
- 8 Logic Switches
- 1kHz Clock (adjustable via external capacitor)
- 2x debounced buttons
- Tie point connections to all devices
- Logic Indicator transparent latches can be reassigned to output drivers
- Solderless Breadboard
Although the LD-1 is now obsolete, an alternative version is still for sale from the TechEdu website.
The price of the LD-1 Pencilbox was $210 when it was discontinued (suspect around 2018). Although it is unknown when the Pencilbox was first designed, revision “C” of the schematic was done in September 1981, with a futher revision “D” in June 1983.
The User Manual for the LD-1 is available online from the Global Specialists website.
| Year | 1981 |
| Make & Model | E&L Instruments LD-1 Pencilbox |
| Generation | Logic Trainer |
| CPU | None |
| Speed | 1kHz (adjustable) |
| RAM & ROM | None |
| Power | 4x “C” size batteries |
| Exhibit No. | 1335 |
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