Always mount a scratch monkey: the real story

There’s an old computing maxim that one should “always mount a scratch monkey”. The most commonly found explanation is that of the Jargon File (and thus the New Hacker’s Dictionary), and while the story is amusing, it is also fairly inaccurate. Recently on a mailing list, a person who was actually involved explained the incident, and gave me permission to reproduce the explanation here under condition of anonymity.

Date: 5 May 2007
From: <name withheldt>
Subject: Re: scratch monkey

The dead monkeys are real, but the story has been garbled. How I remember this — and it’s been over 20 years now — is like this:

I was working for the <institution> Department of Zoology. We didn’t do any experiments with monkeys. You need special permits for that in <country>, which are very hard to get. We didn’t have any. We did, however, have permits to allow experimentation on rats, including neurological experiments on the brains of rats. Those rats had sensors — electrodes — directly implanted in their brains.

This is all very crude and ugly work. Whoever coined the expression ‘this isn’t brain surgery’ has a much higher opinion of the skill required for brain surgery than I have based on what I learned at this point of time.

We read data from the electrodes into a CAMAC crate and there was a complicated way to get the data from the CAMAC crate into a pdp 11/05. From there we could get the data into the 11/44 that was our timesharing system at that time. Note that the computer problem we were solving only involved reading data from the electrodes. Nobody wanted to control the electrodes so that they could administer shocks via the computer.When the electrode manufacturer came out with a new version of the equipment, it looked as if we could do away with the CAMAC crate, which would have been a real blessing. I wrote a driver for the thing, and this was based on a v6 unix disk driver. I can no longer rememebr why I thought that a disk driver was a good model for an electrode sensor driver, though I remember that the sensors had a block mode and a character mode. For 18 year old me, that may have been enough. It could also have been curiosity — I had written 2 tape drivers and a printer driver, and had hacked on a driver for DH-11s, and may have wanted to do something else.

The driver worked well enough, but for the defect that it was un-interruptable. The electrode equipment had no buffering. When it wanted to write something, you really had to give it the whole unibus and lock out everything else including the clock until it was done. This was unacceptable for a time sharing system, and that was where the problem stood. Naturally, we never tested it on any animals.

At this point the professor who was doing the rat experiments decided to take his research someplace else. We all breathed a sigh of relief and forgot all about him. In particular, I did not know that he had taken a copy of my driver with him when he left.

Skip forward a bit. Somebody, I forget where, who was doing primate brain research, with emplanted electrodes in monkey brains got a copy of my driver and modified it to work with a dedicated small Unix machine they had. The electrode manufacturer had released an even newer model, but as far as I know, even that model was not designed to deliver electic shocks on computer command. It did, however, have a self test mode and in running self tests it could deliver shocks.

And one day, a DEC service repairman really did try to run a diagnostic which involved copying data from a test diskpac into what he thought was a different drive which he had loaded with a scratch pack. But he got the volumes wrong — because they were mislabelled at the computer centre — and ended up trying to copy his diagnostic into the electrode driver, which was connected to some monkeys. This ought not to have done anything, but for some reason it did trigger the electrodes self-test mode, which was the cause of the catastrophe.

Some of the monkeys received shocks and at least one of them died. As I recall some of the electrode equipment was made unusable as well, which means it may have been the heat rather than the electricity which was fatal. To make matters worse, the tests were being done at a time when the researchers and the animal technicians who most closely worked with the monkeys were not around. And the monkeys, of course, weren’t in the machine room, but on a different floor of the building. Thus the fact that the monkeys were in distress was not noticed until people came to work the next day. At which point, and rightly so, all hell broke loose and everybody involved in the project was in for a lot of blame, including me because my name was in the comments for the driver.

I’m still pretty embarassed about the whole thing.

<name withheld>

So there you have it.

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