The Open-Hardware RTC8088 Adds a Battery-Backed Real-Time Clock to Any IBM PC/XT or Compatible

Vintage computing enthusiasts Sergey Kiselev and Aitor Gómez García have developed a real-time clock add-in board for those with an IBM PC/XT or compatible — offering an extremely low profile, suitable for even the most cramped of cases.

"[The] RTC8088 controller card is an open source real time clock (RTC) card for IBM PC/XT compatible computers, that typically lack a built-in real time clock," Kiselev writes of the device. "[The] RTC8088 project was originally designed by Aitor Gómez García for use in Micro 8088 systems based on the previous work by Scott Baker, which in its turn partially based on my Xi 8088 project. I updated the RTC8088 V2 project, and added I/O [Input/Output] port configuration switches and DOS device driver."

The joint venture takes the form of a compact Industry Standard Architecture (ISA) add-in board, slotting directly into the motherboard of any IBM PC/XT or compatible personal computer — a family IBM launched in 1983 as the follow-up to its original IBM Personal Computer.

The board features an original Dallas DS12885 real-time clock module, along with a button cell battery holder to keep it ticking over while the PC is switched off. A DIP switch to the upper-left provides the ability to select an I/O address — making it suitable for use with both original IBM PC/XTs and compatibles and with modern Intel 8088-based devices like the Kiselev's own Micro 8088 processor board.

PCBs, including a pre-programmed glue-logic chip, can be purchased from Kiselev's Tindie store for $12, rising to $30 for a full kit of parts bar the CR2032 battery or $35 fully-assembled and tested. Buyers outside North America can buy the same thing from García's Tindie store.

Design files and source code for the project are available on García's GitHub repository, under the strongly reciprocal CERN Open Hardware License 2 and GNU General Public License 3 respectively.