The picture shows an IBM 3380 head disk assembly. There was one set of platters but two actuators. Each actuator allowed access to the data on different tracks of the HDA. You can see the voice coil motors sticking out each side. Each HDA had two channel unit addresses assigned in the system. You couldn't buy just one HDA. They came two in a frame about 3'x3'. There was also another machine, the 3880, that attached to the system channels and the bi-directional 3380 device buss and contained the cache. A full 3380 system consisted of eight frames, sixteen HDAs and thirty-two channel unit addresses. I never paid much attention to the space on the disks because the areal density kept changing over the life of the product, which was about six years for the diehards.

This machine was announced in 1981, but problems surfaced in manufacturing, delaying shipments for six months. It was 1982 before customers actually saw any of them.

I changed many of those at three o'clock in the morning. That's probably why I can recite the particulars after 30 years. That's also why I'm such a stickler for backups. After I changed the HDA, the first thing I would say was, "Call for your backup tapes." On two occasions, I actually hauled a failed HDA to San Jose so the plant folks could recover any data that was still readable.

John:

Out of curiosity, do you remember what the MTBF was on those?

I remember my first HD was a 40 meg upgrade card for around $350.

Sometimes I chuckle when I read people debating whether $399 is too much for the Surface Tablet coming down the road. How expectations have changed!

tom

I'm surprised there were even single 1GB drives in '81, didn't expect that!

I don't remember for sure, but I think that was around the time I had a Tandy TRS-80 with a single 360K floppy drive, no hard drive. And yes, I know big businesses had hard drives back then, just didn't think the Gigs were already out!

And the cheapest surface tablet I believe is $499. But still, compared to what you could get just a few years ago is a good deal.

And system and programs ran in 16K - remember the Commodore 16??
Tom

My first HDD was 120MB and cost £320 circa 1997/8.

"... do you remember what the MTBF was on those?"

That kind of data was not readily available. There were problems all during the life of the product. Still many, many business had good success because of the storage provided by the product.

1) bis-tri-butyl tin oxide used as a biocide in some air conditioners after Legionaire's disease surfaced plated onto the read-write heads and caused them to crash. The next product, the 3390, had sealed HDAs.

2) The 3380 was not tolerent of cold temperatures and the supports for the heads would change alignment over time causing old data to be poorly readable.

3) Near the end of the product cycle, the red oxide versions of the disks suffered a phenomenon called "lube-spinoff" which caused catostrophic failures.