I’ve been doing projects based on Magnetic Bubble Memory for the last few years and I’ve created this post to aggregate information and pointers to one place. I got started on this adventure after visiting Craig Andrews’s website where he had some projects of this own. I bought a couple of the Memtech Bubble Memory kits that he had up on Tindie and started building things.
The Intel 7110 Bubble Memory
Most everything you’ll see in this page is based on the venerable Intel 7110 Bubble Memory and its associated chipset. Here’s an engineering sample that one of my readers was kind enough to send me:
The module on the left is the old-style module that has a plastic socket, and the bubble memory fits into the socket. The one on the right is the newer version that is intended to solder directly to the pcboard. Both of these modules are branded “Intel Magnetics”. You may also find 7110 modules that are Memtech branded, like these:
Note that the modules typically have a series of hex digits. I believe these identify defects in the module and are used to generate a defect map, so you know what elements to avoid. The defect map is stored on the bubble memory itself and can be introspected using the bubble memory controller. Note that the engineering samples have the defect map all set to “FF”.
Multibus boards
I’ve been doing multibus projects lately, and it’s a good time to show off the iSBC-254S multibus board. You may find these boards in the wild with 1, 2, or 4 bubble memories on it, giving a capacity from 128 KB to 512 KB. These are intended for multibus computers, typically used in industrial PLC settings. Bubble memory was a great technology for the industrial sector due to its durability compared to other technologies like paper tape or magnetic tape. I have documented the jumper settings for the iSBC-254S in my github repo. The board is easily usable with the iRMX-86 operating system release 6 and the drivers are built in.
You might also come across the iSBC-264 multibus board. This one uses 7114 bubble memories where are four megabit (512 KB) each. The board pictured below has two bubble memories populated providing a total storage of 1 megabyte. Note that the 7114 bubble memories are likely incompatible with the 7220 chipset used for the 7110 bubble memories. All of the boards that I have seen that use 7114s use the 7225 controller. The board also may have a different iRMX driver than the iSBC-254S — I have not yet tried it.
Multimodules
Multimodules are small modules that are designed to plug into a multibus board, in a piggyback style. The most popular is the iSBX-251, which is a double-wide module featuring a single 7110 bubble memory, for a total storage size of 128 KB.
Here’s a picture of the back side, so you can see how the piggyback connector works. Note that the connector is not a standard 0.100 double-row header. It’s a special connector used on multibus boards, and the profile of the pins is a little more rectangular and a little less square than your typical 0.100 connector. The height is also just a little bit shorter.
I also made a clone of the iSBX-251. Here’s a picture of my clone:
The iPDS was a development system manufactured by Intel, supporting either one or two 8085 processors. It included one or two built-in floppy drives. These systems were popular for programming EPROMs and other devices as well as running assemblers and other tools. The iPDS featured bubble memory as an option. You could use the bubble memory as additional storage, and you could even boot from it — much faster and much quieter than the floppy drive. Below is a picture of an iSBX-251 module plugged into the main board of my iPDS:
HP 98259 Bubble Memory Board for the HP 9000 200/300 series computers
The 98259 is a bubble memory board that was an option for the HP 9000. Built right into the computer are drivers to use the board, and you can load and save BASIC programs to the board. I have never encountered one of these boards in the wild, so I made my own based on Tony Duell’s schematics. Here’s a picture of my board:
Allen Bradley 8000MBC Bubble Memory Cassette
Allen-Bradley, one of the more prolific PLC equiment manufacturers, produced this bubble memory cassette. It has a 7110 bubble memory, together with the entire chipset, inside the cassette. It was intended to the swapped in and out of your industrial PLC system on demand.
Scott’s Basic Bubble Computer
I had the bright idea of making myself a single-board computer with built-in bubble memory. I modified RC2014-Basic for it, and gave it the support to save and load BASIC programs to/from the built in bubble memory. You can read more about it here.
At the same time, I built a bubble memory board for the RC2014. It’s kinda big and dwarfs the rest of the RC2014 computer. You can read about it on the same page as the basic bubble.
Heathkit H8 Bubble Memory Boards
Yeah, I was on an H8 craze for a while, and I made bubble memory boards for the H8. Read about it here. I added boot support and the ability to use it in HDOS.
I decided to try my hand at designing a dual bubble memory bnoard, so I made the “double bubble” for the H8 as well. It supported 256 KB of storage.
