The evolution of the hard drive

I've actually worked with a VRC drum. I think it rotated at either 25rpm or 175 rpm and could store 32 hours of real time data. You could see the magnetic surface and it had numerous heads. It sat on the floor and was about3.5 to 4 feet high(1.2m).. the drum was at least 2 feet (.6m) in diameter

Here is a similar one

http://www.computermuseum.li/Testpage/Drum-Memory-Unit-VRC-1967.htm

Now take this technology to the next level and you'll see how inadequate we were in Landing on the Moon ! tee hee

We used two different floor model disk packs in a clean room. One had 6 heads (5 read/write and one track) while the other about double

I remember repairing the floor model disk drives in the 1980s. A single head typically cost $156.00 if it was on top and $175.00 if it was on the bottom. The track head cost over $225.00.

The unfortunate part is that usually more than one head would crash.

These heads "flew" over the surface at a height of one millionth of an inch.

Interesting enough Bubble memory was also created in 1967 but was forgotten due to cheaper hard drives. Bubble memory is more reliable then any magnetic storage or flash memory,

Bubble memory??? Tell us more about this...

I'd like to tag along as I am also interested in learning about bubble memory.

See wikipedia for a lot more on this.

Bubble memory was non volitile memory where a "1" or a Zero is stored in a magnetic bubble.

It required 15 volts to write to it, yet operated as read at the normal 5 volt TTL standard.

here is a link

http://en.wikipedia.org/wiki/Bubble_memory

a simple write up on the history

http://www.dvorak.org/blog/?page_id=8249

In fact when I first heard the term Thumb drive, I thought it was bubble memory, since a serial port has control signals at 15 volts. It was not until I heard the term "flash memory" that I realized it was simply UV erasable programable memory and has the weakness of limited write cycles.

Do you remember the first 12" floppies? A whole megabyte of storage.

Yup!, I remember the drum.We had a 512 fixed head, 3600 rpm drum unit in 1977.It could store 20 million 16 bit words, and was very fast.The computer also had 16k of core memory, and was a Sperry Model 70, I think.A mini-computer, not a micro.Even so, it had a whole room for itself.The I/O panel was actually larger than the computer itself.The drum required 17ea. 8 inch floopies to back it up, and it also had a punch-card reader. A man was put on the moon with slide rules (remember them?) and a computer with less power than a calculator has today. We have truly come a long way, but we have far to go. In 35years, people will look back and think how primitive we were, as we do when we look back 35years. Exabyte memory incorporated into buttons on your clothes.Landfills full of microscopic computers, cheap as dirt. Heads up display incorporated into your optic nerve, wirelessly communicating with others via thought amplification, and a million other things I have never even dreamed of. HTRN

Look in Smithsonian. I arranged for the very first closed loop process control computer to be sent to the Smithsonian to replace the replica on disply. It had drum memory.

It was used to control a very 'fast' propylene polymerization process--it was highly exothermic, and polymer was desired as a mix of trimer and tetramer . Feed forward control of reaction temp was essential.

multipy that thousands by many tens (up to more than 10 tens) and you're closer to the "price." Remember though that these machines were never purchase, only leased (there was no price)...until gates and the pc broke down IBM; something like the western electric (bell company) phones before the breakup of ATT. I vaguely remember the RAMAC--didn't get hands-on involved as a child until operating the 1401...the huge platters, etc. Printer were most impressive: could print out, seems now like, about 5-10 large pages in the time it takes nowadays, personal printers, to print one or two lines. Then there were the plug boards with hornets nest of wires that had to be pulled and rewired to set up the CPU... And those huge stacks of punch cards that needed keypunching, running through collator and finally loaded into the CPU. Lotsa labor involved compared to today. Back then no one got fatassed in the data processing trades, except programmers.

bulb memory almost to forget all now.

as well as megnetic drum.