Categorie: science

The roots of modern computing explained in EWD51 – Multiprogramming and the X8

Dijkstra’s EWD 51 is a structured educational coverage of the workings of semaphores in communicating processes and with IO devices. It is the first part in a series of three articles called MULTIPROGAMMERING EN DE X8″ (Multiprogramming and the X8), EWD54 and 57 describe part 2 and 3.

The X8 is the Dutch research computer for which Dijkstra and hos team developed the operating system, and he was able to test his now famous concepts for multiprogramming. 
In a way it is the formal part of the talk that Dijkstra held and was transcribed in EWD 35.

EWD 51 extensively discusses the mechanisms of semaphores, the conditions, and (hardware) implications. That is the summary. To give more would be pointless, and you’d rather read the entire article. (The article is in Dutch – I could provide a quick translation if you are interested. Please let me know through a comment on this post, or send me an email)

The Dutch language used in this article is highly interesting. Dijkstra invents concepts for which no words existed before (seinpaal/semaphore as computing concept to start with) the abbreviations P (prolaag/pass – probeer te verlagen) and V (verhoog/increase), critieke secties / critical sections, ingreep-flip-flop / interrupt-flip-flops, luisterbit / listener bit, doof-horend bit.

The article could still  function as a modern introduction into the topic and still be applicable to today’s computers.

So far ahead, so clear, so up to date still.

Sloppy Lifebox print, great read from Rudy Rucker

Annoying: page 237 through 240 are shuffled in my print of The Lifebox, lifeboxcoverthe Seashell and the Soul. Though not entirely surprising: the crumbly paper was a indicator for a sloppy edition. Maybe it is a collector’s item now. Mail me and you can have it.

I bought it about ten years ago, and recently reread Rudy Rucker’s The Lifebox, the Seashell and the Soul It is a very interesting book, although smelling odd here and there.   Lees verder “Sloppy Lifebox print, great read from Rudy Rucker”

Thrilling footnotes in Science History: Lovelace and Babbage illustrated

Sydney Padua wrote and drew the graphic novel / graphic documentary book The Thrilling Adventures of Lovelace and Babbage (see also here).lovelaceandbabbagemockup-e1427555729647

These type of wonderful books I am convinced will never be replaced by ebooks. Sydney Padua wrote a beautiful graphical novel or documentary (it’s actually a new type of book) about Charles Babbage and Ada Lovelace Byron, the world’s first inventor respectively programmer of the computer.
Padua is an illustrator and documentalist, and has created a piece of art with this comic style documentary. Lees verder “Thrilling footnotes in Science History: Lovelace and Babbage illustrated”

Douglas Adams’ Salmon of Doubt on Beatles, Bach, Wodehouse, technology, Apple, atheism and hurling the chairs around.


Douglas Adams

Douglas Adams died young. Aged 49, in 2001.

But in his short life he wrote The Hitchhiker’s Guide to the Galaxy. Enough for a meaningful life.

The Salmon of Doubt bundles the unpublished work he left on his Mac when he died. Lees verder “Douglas Adams’ Salmon of Doubt on Beatles, Bach, Wodehouse, technology, Apple, atheism and hurling the chairs around.”