“640K ought to be enough for anybody,” Bill Gates famously once said, referring to RAM in PCs. Or at least he’s rumored to have said—the man himself strenuously denies the attribution and a number of sources who have worked to trace the provenance of the comment have come up short. That said, as this slideshow demonstrates, 640 KB was a stupendous amount of memory for the time. Take a look back at some of the early technologies used for digital data storage—and realize that it would probably take dozens of them to deliver the same capacity as in your average car key.
Not to mention the absolutely wonderful "rope memory" used in the Apollo Guidance Computer systems. A form of almost physically indestructible ROM in which the memory contents were encoded (literally "hard-wired") by weaving (by hand) the sensor wires in and out of a string of ferrite cores.
Changing the contents of the memory meant unravelling the string and re-weaving the wires.
Besides programming computers that used core memory, I bought some from a computer museum along with a silicon wafer. I took both to work one day to show the other programmers. Our 17 year old genius programmer thought the wafer was pretty cool, but when he looked at the core memory, he turned to me and asked, "How does it hold a charge?"
I remember these types of ROMs. I worked with one that worked as a character generator for a graphics display terminal, Computer Dispays Inc. ARDS.
It was made of wires passing, or not passing, through the magnetic circuits (ferrite posts). The bottom had a bed of posts and a lid that (I think) completed the magnetic circuit.
To edit, one had to lift the lid, clip a wire and then add a new one, going a different rout through the posts, connect the new wire and replace the lid.
Thank you Kristin! interesting article.
In the 1980s, for a few years, magnetic bubble memory was going to be the future of mass storage. Magnetic domains coded as North-South or South-North were steered around loops on a specially contructed ferromagnetic substrate.
Bubble memory was too slow and never quite made it and the Winchester disk (and its derivatives) only now becoming overtaken by 'Flash' solid state technology.
Magnetic memory, I was reminded, when recently clearing out my attic, that as a cross between magnetic bubble memory and the latest racetrack memory, the magnetic CrossTie memory was once expected to do great things in the world of disc replacement and NV memory. Its structure was characterized by a series of sawtooth shaped films facing each other with the magnetic bits stepping along between opposing teeth.
The other memory museum piece I found in the attic is a non-destructive readout magnetic square-loop core. This is a normal core with a second hole in the annulus that allowed the state of the main core to be read non-destructively. It appears to be wound with five wires. I think in application it was intended to serve as both a logic and memory device.
When I was programming conveyor systems I was introduced to, but thankfully never had to use, "Ball memory". It consisted of a series of wagon wheels(?) with a U channel carved in the rubber diameter. These wheels would be mounted a a single shaft with each wheel controlling a single diverter. The rotation of these wheels was geared to the movement of the conveyor belt. When a carton was destined for a certain lane, there was a solenoid that would inject a steel ball bearing into the U channel of the wheel. A microswitch would be positioned around the wheel at the location timed with the carton being at the diverter. The ball would be scooped out before making a complete rotation. A common problem was that the operators would forget to refill the input tray with the balls in the output tray.
I know, not really electronics, but the mercury delay memory reminded me of it.
David Patterson, known for his pioneering research that led to RAID, clusters and more, is part of a team at UC Berkeley that recently made its RISC-V processor architecture an open source hardware offering. We talk with Patterson and one of his colleagues behind the effort about the opportunities they see, what new kinds of designs they hope to enable and what it means for today’s commercial processor giants such as Intel, ARM and Imagination Technologies.