Jeffrey Birt's Memory Module Recreates Casio's Classic RP-33 RAM Pack with a Modern Twist

Designed for production using hobbyist small-scale manufacturing techniques, including 3D printing, this module adds 32kB of static RAM.

Gareth Halfacree
7 days agoRetroTech / 3D Printing

Self-described "professional nerd and tinkerer" Jeffrey Birt and colleagues have put together a modern memory upgrade for vintage Casio pocket computers, designed to be functionally equivalent to Casio's own RP-33 module.

"Back in the day Casio offered a 32K RAM upgrade for several of its pocket computers. The module could be installed by the user to boost the available static RAM by 32k," Birt explains. "These days the original RP-33 modules are rare as hen's teeth so with the help of some friends we created our own."

Designed to be compatible with a range of Casio pocket computers, including the FX-8 series, FX series, and AI-1000, Birt's recreation blends the features of Casio's original design with a desire to make it suitable for small-scale hobbyist manufacturing — including the use of a 3D-printed mount for the "zebra strips," which provide a connection to the host device.

Installation of the boards, which are provided fully-assembled, is identical to those of the original — bar, perhaps, the suggestion to clean the computer's contacts with alcohol after a few decades of going unused. The memory board is inserted into the pocket computer from below, held in place with screws, and then the system reset ready for testing.

"If the test returns you back to the menu it has passed without error," Birt writes. "If you happen to get an error take module back out […] and make sure the contacts are clean and the module is centered."

The boards are now available on Birt's Tindie store, priced at $32 each before volume discounts.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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