Dr. Scott M. Baker Restores a Vintage Portabubble/81 — and Demonstrates the Power of Bubble Memory
A couple of quick repairs to a 1980s portable word processor show that magnetic bubble memory really is non-volatile — and long-lasting.
Vintage computing enthusiast Dr. Scott M. Baker is having another play with bubble memory — this time by restoring a Teleram Portabubble/81 machine, a luggable microcomputer designed primarily with the needs of in-the-field journalists in mind.
"Magnetic bubble memory has always been a fascination of mine, and one of the primary features of the Teleram Portabubble was that it used bubble memory for non-volatile storage. It had no disk, no cassette, no other forms of persistent user data storage other than the bubble memory," Baker explains. "My understanding was that these were marketed at journalists and similar folks who might need to write a story remotely. They write up their story on the Portabubble then send it in to their newspaper via the acoustic coupler. I’m told this Portabubble was previously used by Sid Hartman, a sports reporter who worked in Minnesota reporting on NCAA games."
The not-terrifically-portable Portabubble/81 was released in 1980 as a microcomputer-based cross between an electronic word processor and a portable terminal. The device featured a 5" cathode-ray tube display (CRT) and a full-size keyboard, while the surprisingly deep housing included rubber cups connected to a built-in acoustic coupler modem — meaning the machine could be connected to a phone line by dialling a number and inserting the handset into the cups, then the contents of its roughly 20,000-character memory transmitted.
It's that 20,000-character memory that caught Baker's attention. Where contemporaneous systems may have used floppy disks or cassette tapes for non-volatile storage, the Portabubble used magnetic bubble memory — where magnetic "bubbles" can be moved around a looped substrate for the purpose of reading or writing to the memory. Unlike static and dynamic RAM (SRAM and DRAM), bubble memory is inherently non-volatile: cut the power, and so long as the magnetism remains intact so too does your data.
The used Portabubble that landed on Baker's desk shows just how long-lived bubble memory can be: after repairing the keyboard and a fault with the monitor, Baker was able to read the contents of the machine's memory without error: sports reportage written by journalist Sid Hartman in the 1980s and 1990s, presumably his last before moving onto a machine that could fit in a briefcase without detaching your arm.
Baker's full write-up is available on his website, with further detail in the video embedded above and on his YouTube channel.
