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DRAM Tester for 4116/4164/4532: Diagnosing Dead Spectrum Memory

19 August 2026

DiagnosticPCBWay buildRepair

Difficulty: Intermediate — Arduino Nano firmware flashing required · Fits: ZX Spectrum 16K/48K (4116/4164 DRAM), plus any other 8-bit machine using pin-compatible 4116/4164/41256/4532 DRAM — e.g. the Commodore 64 and 16

A 16K or 48K Spectrum with corrupted or garbled memory is nearly always down to a single faulty DRAM chip somewhere in the bank, but with eight or sixteen identical-looking chips on the board, finding which one is dead by substitution alone is slow and easy to get wrong. This tester takes one chip at a time, out of circuit, and tells you directly whether it's good.

It's built around an Arduino Nano and a 128×32 I2C OLED display: a jumper selects which memory type is under test (4116, 4164/41256, or 4532 and pin-compatible parts), a ZIF socket takes the chip without bending any legs, and a single button press runs the test — a longer, sustained press starts it, brief taps cycle through the memory-type selection. Results, including the specific failing address if a chip is faulty, show up on the OLED. As the designer is upfront about: it's not a 100% guarantee — a chip can pass this test and still misbehave in a real circuit — but it's a fast first pass across a stack of pulled chips.

Designed by Mirco Gaggiottini ("Retrofixer"), released under a Creative Commons Attribution-NonCommercial (CC BY-NC 4.0) licence. Firmware, 3D-printable case files, and full build notes are on GitHub.

Build notes

The Arduino Nano needs the provided .hex firmware flashed via AVRDUDE (or the AVRDUDESS GUI if you'd rather not use the command line) — no Arduino IDE compile step required unless you want to modify the firmware yourself, in which case the u8g2lib display library is a dependency.

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