'Real' Programmers & Drum Memory - Computerphile

Discussing "Real" Programmers from the early days of computing with Dr Julian Onions.

n.b. When Julian mentions "Real" programmers, he refers to the endless jokes that circulated on early online communities like Usenet.


This video was filmed and edited by Sean Riley.

[davidgustavsson]

This was no doubt a time when programmer time was cheaper than processor time.

[thea.igamer]

Real programmers move electrons by hand

[mentatphilosopher]

Worked on a TSPS Switch with drum memory the size of a full size washing machine drum. Only element in the switch that was AC to spin it. It stored data tables and had a separate bit in the 34 bit word (32 data, 1 parity, 1 table end mark) to mark end of a table. The table search was hardware implemented. Give the start of the table on the drum and a key and key size and record size and it would search until a match or the end of table mark was found. Still in field use until the end of the 1980s.

[jerrykew]

In 1976 I worked in the machine room in Wythenshawe for Shell. Big space, 3 mainframes, Two Univac and an IBM 370. They had corridors of drum store. The stats were astonishing, they weighed a quarter tonne each. I *think* 4 heads per track(1/4 latency), and 20, 000 rpm. Apparently, they took hours to power up. I never saw that as that only happened on an airconditioning weekend (I wasn't invited :-) ). We had permanent Univac engineers on site. If a unit (tape deck, IOAU, CAU disk, drum etc) went down we handed that cabinet back to Univac, and they handed it back to us when working. 24hour ops of course. Only paid for it working, early AWS!!. Anyway, back to the drums, the engineers were aware of two globally that had had their bottom end bearings fail. Apparently one 'walked' through a couple of CPU or whatever cabinets and exited through a wall, the other had drilled down through the building, you don't argue with a quarter tonne at 20k rpm. I'm sure there was artistic licence to the tales, but I can still recall nervously walking the drum corridors, occasionally peering through the vertical spyglasses at the seemingly motionless drum behind.

[Tasarran]

Wouldn't these be... drum memory roll... 'reel' programmers? :D

[MisterMcHaos]

I would encourage anyone who's interested in this sort of content to acquire and read a copy of "The Jargon File".

[compu]

Having the data positioned so that it's "ready" at the same time as the processor was used for spinning disks for quite a while - it's called interleaving. On the original PC the hard disk had an interleave of 5 - the disk controller and processor were slow enough that it took 4 sectors of time before they'd be ready to read in the next sector!

[gerteldering]

This reminds me of the story I heard in the early seventies that one of our genius "real" programmers succeeded in crashing a hard disk by moving the read/write head of the disk continuously between the innermost to the outermost cylinder of the disk. The drive was designed for random access in the literal sense of the word and not for that kind of action and it started to resonate in some way until it crashed.

[usafa]

Real programmers use Verilog to CREATE the hardware, then programs down to it.

[john_g_harris]

The people writing programs for the English Electric Deuce computer (drum + mercury delay lines for fast access) also wrote in binary. All the tricks Julian mentions were in use which made them 'real' programmers as well.

[moofree]

Reading instruction codes as integer inputs is pretty awesome.

[jwizardc]

The first computer I wrote (The Mark I) for had drum memory. It also had a separate Arithmetic and Logical units. My favorite "trick" was to the machine cycles that were required for a mathematic operation and execute logical instructions. For example, the divide instruction took 12 cycles. That works out to 8 - 12 logical instructions while the math unit cranked.
It also had (if I remember correctly) 12k of 24 bit words of ram.

Ouch. It hurts to remember that far ago.

[aliceanderson]

"Real programmers go straight down to the metal"

[dipi]

So many interleaving techniques related to these drum-based tricks. e.g. spiralized sector formatting for fast-loading data from floppy disks.

[werdna]

Heard the following from a former co-worker - take it as you will. A new drum-based hard drive was deployed to an airport control center. The drum spun at a "gajillion" RPM. It also had a foot pedal to activate an emergency brake. The emergency brake was rated for one use. The U.S. Federal Aviation Administration regulator required the installer to demonstrate that the emergency brake worked. In other words, spin up the disk and activate the brake. Installer explained that would use up the one-and-only-one guaranteed brake activation. Regulator didn't care. "Rules say..."

[RonJohn]

Don't forget that Real Programmers Don't Comment Their Code.

[stephenwoods]

Also plotters, that used stepper motors to move paper and pen in X and Y, by default the time per step was .01 second which made the damn thing very noist as the stepper motors had to stop and start. Adjusting the pot on the controller to run at about 120+ Hz made everything run much faster, 10 times more quiet and cooler as well. A three way win. OH yeah and it ran the diagnostic perfectly (the diagnostic drew trefoils all around and inside a square and were supposed to over trace the previous run (if you hadn't dropped any steps).

[DamonWakefield]

Brings back memories of my time at MIT when we programmed on a PDP-2.

[computer_toucher]

Wow, the video was about exactly what I'd thought it would be after reading the title :)

[patternwhisperer]

"Real" programmers use their computer science education to apply/choose appropriate layers of indirections to get their jobs done :^)