It’s not news that computer technology gets smaller, faster, less costly, and less power-consuming over time. But occasionally something happens to bring these changes into sharp personal relief.
This just happened to me.
This is a tale of two disk drives. The comparison isn’t exactly apples-to-apples because some of the attributes are estimated, recalled from memory, or not measured in exactly the same way.
Here we go.
The DEC RP20 disk drive
Forty-four years go, in 1980, I was working for the greatest company in the universe: Digital Equipment Corporation (DEC). In August 1980 DEC announced a new disk drive for its DECSYSTEM-2040 and -2060 systems: The RP20. From a 1982 Datapro publication:
The RP20 was a big deal. It was A GIGABYTE OF STORAGE in one cabinet using two spindles. An entire gigabyte! Holy cow! (It was really 929MB but we all rounded it up to 1GB.) I remember feeling a chill when I first saw one.
My memory is hazy but the RP20 may have also eventually been supported by the DECsystem-10. I found a digitized printset suggesting this.
A DEC disk history page lists some RP20 technical information.
| RPM | 3,500 (with a question mark) |
| capacity | 1GB (rounded up from 929MB) |
| seek time | 25ms |
| transfer rate | 1.2 MB/second (one source), 1.3MB/second (another source) |
I can’t find power consumption information. Power consumption was a minor factor in calculating systems’ TCO and preparing for installation, because all large systems consumed a lot of power and market competition around it just didn’t exist. Every large system consumed a lot of juice.
I can’t find size information. From memory, I recall it standing a little less than chest high. I think it occupied a total volume of 3.5′ x 6′ x 3′ = 63 ft3, or 108,864 in3.
List price: $51,000 in 1980 dollars. That’s about $194,000 is today’s dollars. I have no information on what discounts were given to close sales, so I’ll use the list price.
It also had a hardware maintenance cost of $308/month, which is $1,172 in today’s dollars.
The RP20 was almost certainly an OEM’d product. I vaguely recall that it was made by STC. Like all of DEC’s products, it wasn’t the epitome of its class. It was a competitive drive but I think it was a stopgap until better products were ready for market. In fact, it was eclipsed in only one or two years. DEC wasn’t a storage powerhouse but even its storage solutions saw rapid improvement in the 1980s.
The Western Digital Red Plus 3.5″ internal disk drive
My home NAS has four 4TB drives. It’s full. It’s time to upgrade.
Because I’m cheap frugal, I’ll upgrade it in-place. Yes I know it would be safer to buy another NAS and copy the current NAS’ files to it, then sell the current NAS. I’m not hurting for computes so I’m going to go the cheaper but riskier route of upgrading in place. I have an off-site backup of all of the files.
I like Western Digital products. They have multiple HDD product lines. For my purposes the Red Plus line is most appropriate.
I’m upgrading my NAS to four 12TB Red Plus drives. The stats for this drive:
| RPM | 7,200 |
| capacity | 12TB. That’s 12,000 GB |
| seek time | 29ms |
| transfer rate | up to 196MB/second |
| list price | $239.99 plus shipping and tax |
| volume | 23.8 in3 |
| hardware maintenance cost | $0.00 / month |
| average power requirement | 6.3W when reading or writing |
Like the RP20, this drive isn’t the epitome of disk drives. It’s competitive but isn’t at the top of its class. It’s an OK drive for a home NAS. Reasonable arguments can be made that there are better drives for the money. I like Western Digital products so it’s what I bought.
It’s an internal drive, and the RP20 was an external drive.
Let’s compare
| Attribute | DEC RP20 | WD Red Plus 12TB |
| Year of introduction | 1980 | 2020 |
| capacity | 1 GB | 12,000 GB |
| list price in today’s dollars | $194,000 | $240 |
| $ / GB in today’s dollars | $194,000 | $0.02 |
| volume | 108,864 in3 (from my memory) | 24 in3 |
| bytes / in3 | 9 K | 500 B |
| power consumption | don’t know but I bet it was hefty | 6.3W |
| transfer rate | 1.3 MB/second | up to 196MB/second |
| seek time | 25ms | 29ms |
Wow!
Seek Nuance 