50th Anniversary of hard disk

According to this source:

the introduction date for this drive, the IBM 350 Disk File (part of the IBM 305 RAMAC computer system) was Sept. 13, 1956 (other sources, including IBM's own site and Wikipedia, say September 4, 1956). I buttume the celebration Robert notes was the date they first got it running or some similar important milestone. The article also notes that this was the birth of the first suspended head (i.e.: non-contact) hard disk rather than the birth of hard disks in general. I'd always thought that all rotating media before this disk was drums.

Here's a picture of that computer with the disk drive shown prominently in the background:

Here's a bit of video about it.

This source:

says it was announced on May of 1955. In fact, this article has something of a time line in it. I didn't run across any date which coincided with January 28th.

Here's a really good picture, including a shot of the inside, on IBM's own history site:

I can't find the HP of the motor, but it looks big enough to power a car. In fact, it looks like the ones they use to convert project cars from gas to electric.

Robert. You've piqued my curiosity. Was the Friday, the 28th, just a convenient day they picked for the celebration, or was it actually significant as 50 years, to the day, after some mile stone?

- Bill