Friday, January 30, 2004

A Three Fingered Salute

Gentle reader,

Dave Bradley has retired.

Who.

Well in his own words.....

-START-

I claim to have "invented" CTL-ALT-DEL. In September, 1980 I was one of the 12 engineers in IBM that moved from the System/23 DataMaster development to a project called Acorn. Over the next 6 months I wrote nearly all of the assembly language code that became the ROM BIOS of the IBM PC (Appendix A of the original Technical Reference Manual). Included in that was the horribly messy keyboard decoding logic that contain the CTL-ALT-DEL sequence.

During development it had become obvious that we needed a way to warm reboot the system when programs hung. We didn't have a reset button, and even if we had had one, it would have sent the processor all the way back through the long Power On Self Test. So I added a special key sequence that would effectively reset the hardware, but would bypass the long memory test. I had done something similar in the System/23 DataMaster.

I chose the keys so that (a) it would be unlikely to accidentally hit the combination, so there were three widely spaced keys, and (b) it wouldn't take much code to do it (we used 8168 bytes of the 8192 available to us) so two keys were shift keys.

We originally hadn't intended to make it a user feature, but it became so much a part of the software development process ("...to start the program, insert the diskette and hit CTL-ALT-DEL...") that it became a public part of the system.

Dr. Dave

Dave Bradley
drdave@u...

-END-

take care,
Will

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