Instead, like a modern dynamic RAM, it used capacitors.ĭrum storage remained useful as mass storage for a number of years. The Atanasoff-Berry computer used a device similar to a drum memory, but it didn’t use ferromagnetic material. The original IBM 650 had an 8.5 kB drum memory.
A few drums had heads that would move over a few tracks, a precursor to a modern disk drive that typically has one head per surface. A typical drum had a number of heads (one for each track) and simply waited until the desired bit was under the head to perform a read or write operation. Where a hard drive uses a platter, the drum uses a metal cylinder. Like a hard drive, a drum memory was a rotating surface of ferromagnetic material. Although later computers used the technique as secondary storage (like a modern hard drive), some early machines used it as their main storage. Surprisingly, drum memory–a similar technology to a modern hard drive–first appeared in 1932 for use with punched card machines. What did early computers use for fast read/write storage? In fact, they are relatively newcomers to the scene. However, computers didn’t always use static and dynamic RAM. There’s also things like flash memory that are useful, but can’t displace regular RAM because of speed, durability, or complex write cycles. Sure, there are a few new technologies that could gain wider usage. Static RAM lives in your PC, too, as cache memory where speed is important.įor now, at least, these two types of RAM technology dominate the market for fast random access read/write memory. They don’t require refreshing, but a static RAM cell is much larger than an equivalent bit of dynamic memory, so static memory is much less dense than dynamic. This is more or less an array of flip flops. The other kind of common RAM you see is static.
THANKS FOR THE MEMORIES PC
All of the common memory you plug into a PC motherboard–DDR, DDR2, SDRAM, RDRAM, and so on–are types of dynamic memory. The upside is you can inexpensively pack lots of bits into a small area. The downside to that is that the RAM is unavailable sometimes while the capacitors get refreshed. Today just about all RAM (at least in PCs) is dynamic–it relies on tiny capacitors to hold a charge. I can remember how big a deal it was when a TRS-80 went from 4K (that’s. I was buying a new laptop the other day and had to make a choice between 4GB of memory and 8.
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