Saturday Scenes

Fri 2 August 2013

The Quick and Dirty OS

Filed under: #satscene —— Sylvia @ 18:33

On the 27th of July, 1981, Microsoft bought the rights for QDOS (Quick and Dirty Operating System) for $25,000.

IBM had approached Microsoft regarding an operating system for its upcoming personal computer. The IBM PC was due for release in August, so the QDOS purchase was just in time. This original version of DOS was designed by Tim Paterson.

DosMan Drivel – Tim Paterson’s Blog

I envisioned the power of the 8086 making it practical to have a multi-user OS, and I laid out a plan to the SCP board of directors to develop a single-user OS and a multi-user OS that would share the same Application Program Interface (API). This would be a big design job that would take time to get right – but we were already shipping our computer system and needed an OS now. So I proposed to start with a “quick and dirty” OS that would eventually be thrown away.

When I designed DOS I knew that fitting the cluster number in a single byte, limiting the number of clusters to 256, wouldn’t get the job done as disks got bigger. I increased the FAT entry to 12 bits, allowing over 4000 clusters. With a cluster size of as much as 16K bytes, this would allow for disks as large as 64MB. You could even push it to a 32K cluster and 128MB disk size, although that large cluster could waste a lot space. These disk sizes seemed enormous to me in 1980. Only recently had we seen the first 10MB hard disks come out for microcomputers, and that size seemed absurdly lavish (and expensive).

Thirty-two years later, SatScenes was put together on a machine running Windows 7 with two hard-drives of 931GB each. That’s X* times the 64MB disks that Tim Paterson designed for. These are the wonderful photographs that were submitted:

*I don’t think I can count that high

And here are the photographers who took them!

Have you got a camera or a smart-phone? Has it got as much memory as a microcomputer in 1981?

In that case, you have no excuse for not taking a photograph on Saturday. It’s easy to join us!

Simply send a tweet to @SatScenes with the url and the location and all the rest happens automatically!

I’m looking forward to seeing your Saturday Scene in the next edition!

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