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Comment by rwmj

3 years ago

The concept is old as the hills, if you include static RAM. It was a common way for early digital synthesizers (early 80s) to store patches in battery backed SRAM. Even on removable cards.

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rwmj

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dboreham  3 years ago

My first encounter with the concept was in 1982 during the summer working at an electronics company. We used the then new 64K DRAMs in production so there was a ready supply of devices vendors had given us for evaluation. I built a 128KB memory board with bank selection logic then wrote a driver for the Flex OS (6809) to make that memory appear like a disk. Also built a similar board with (probably, long time ago..) 27128 eproms that worked as a "ROM-Disk". I doubt I invented the ram disk. I'd probably heard of the idea somewhere, but I hadn't actually seen an implementation before the one I made.

The next year I switched to a larger company for summer work (defense contractor) and there wrote a driver for CP/M that talked to a "server" I wrote running on their VAX (via 19.2K serial). It made a large file on the VAX look like a disk to CP/M. We used this arrangement for backup -- copy all the files from the physical hard drive to the remote drive. Again I don't believe I'd seen this done before but it was a fairly obvious extension of the previous ram disk idea.

Unfortunately it turned out the group I worked for got billed by the computer dept for CPU time and I/O on the VAX and my network attached storage scheme ran up a huge bill so had to be abandoned.

  • jonsen  3 years ago

    > I built a 128KB memory board with bank selection logic then wrote a driver for the Flex OS (6809) to make that memory appear like a disk.

    Oy! I could have written exactly that. What a coincidence :-) I also wouldn't claim invention. Maybe I heard of it, but I'd say the idea is pretty obvious. We made it possible for Flex to run to programs simultaneously and also do print spooling. (That's when I bought an HP 16C. Great help. Still have it.)