Modifying a Dallas clock chip (DS1287) to work with an external CR2032 battery

Sometimes bringing back old tech requires more than dusting and testing — it requires some surgery, patience, and a soldering iron. On one of our recent retro hardware excursions, we stumbled upon a dirty, early 1990s 386 laptop. It was rocking a cute monochrome display, a tiny keyboard, and all the signs of not having been handled in decades. But internally, we knew we were in for a fight: the infamous Dallas RTC (real-time clock) chip with the internal battery.

The Dallas chip on this unit, like on many from the era, had a dead internal battery — a ticking time bomb in older computers. With a dead RTC, the system couldn’t boot, and there wasn’t an easy way of replacing it since the battery was sealed inside the chip. Our mission: restore life to this laptop.

We began by carefully opening up the machine and extracting the motherboard. The Dallas chip was located and desoldered from the board right away in preparation for the tweak.

The tricky step came next — we had to access the internal battery pins of the Dallas chip. This meant gently sanding the case to expose the region near pin 20 (positive) and pin 16 (ground). We marked the locations carefully to avoid damaging the internal connections.

With the contacts now exposed, we soldered thin wires to the respective pins, forming a sound connection without shorting anything. This would allow us to power it with an external battery — a standard CR2032 — instead of the long-dead internal cell.

Wiring complete, we mounted a socket for the CR2032 coin cell, hot-gluing it to a nearby IC. Wires were carefully dressed and tied down to avoid strain or interference.

After verifying all connections twice, we mounted the hacked chip back on the board and began reassembling the laptop. The tension was palpable.

We then powered it up — and, to our amazement, the laptop booted straight into Windows 3.11, complete and ready to live again in its digital past.

This kind of restoration is what the 8bit Club is all about — bringing life to old forgotten machines, preserving computing history, and having fun while doing it. So, if you have an old Dallas chip laptop sitting in the dust, don’t discard it — it might just need some surgery and a sprinkle of CR2032 magic.