“Our logic is full of holes...
I can see the bubbles.”
Saturday 22nd November, 2008
An approximation to beauty: sitting in Arlanda airport, watching the snow fall over the aeroplanes and the lights move on the vehicles, listening to Kodaly's Laudes Organi very loudly.
by Rob Mitchelmore, 02:29 (anchor)
Wednesday 24th September, 2008
Oh to walk my way with kindness,
And not betray my life to a cloud of suspicions...
How I wish that someone would believe me,
How I wish that I could believe someone.

To triumph in an unequal battle,
To embrace with love both small and big,
How I wish that someone would believe me,
How I wish that I could believe someone.

Let the silence burst forth with fury
And the eternal noise die down for good...
How I wish that someone would believe me,
How I wish that I could believe someone.


— Hamo Sahyan

by Rob Mitchelmore, 01:19 (anchor)
Tuesday 8th April, 2008
IPMI polling on Dell PowerEdge R200s (and other Intel CPU rackmounts): polling the Dell PowerEdge R200 using IPMI-over-LAN, it may be surprising to find the 'Temp' sensor reporting comfortably arctic temperatures, low to the point of being sub-zero, and critical failure:

Temp             | -52 degrees C     | cr

In moderately recent time, Intel have taken to giving this temperature not as an absolute temperature, but have instead redefined the scale of Degrees Celsius so that it is measured relative to the "melting point" of the CPU.

Once this is compensated for, it should give the actual temperature of the machine.

by Rob Mitchelmore, 17:01 (anchor)
Sunday 13th January, 2008
A partial solution to the Nokia N800 boot issue: there is a problem, or a family of related problems in booting on the Nokia N800 linux tablet, where the tablet will not power on correctly when connected to a mains output and will not charge reliably - or at all.

The solution to this in some cases is to turn off extended virtual memory on the memory card (under Control Panel - Memory), as this appears to impact the way it 'boots' to go into charging mode. Battery charging appears to be largely software-monitored and controlled.

Of course, this rather depends on the machine booting in the first place; in some cases the machine will boot intermittently (which sounds like a timing issue), if it does not then a solution may be to get hold of an offline, 'dumb' nokia battery charger to give the tablet battery an initial charge.

You may also find that removing the battery for a while helps.

by Rob Mitchelmore, 14:27 (anchor)
Monday 3rd December, 2007
A peacock-like fan with each feather an ivy branch escher-tesselate; in the middle of each leaf a single eye with slowly dilating pupil and all in the reds and golds of autumn.

Watching.

by Rob Mitchelmore, 23:05 (anchor)
Tuesday 2nd October, 2007
The Apple Lisa Office System GUI: an exercise in digital archæology.

All screenshots have been produced with LisaEm, which incorrectly draws scroll bars. This is an emulator issue and not an issue with the OS itself. Apart from this glitch, the emulator seems to be stable and usable.

It is tempting to view the Apple Lisa Office System as a prototype for the Macintosh; this is not, however the case, as beneath its slightly clunkier visual appearance, it is certainly a more sophisticated operating system than the Macintosh System was intially, and in some ways a more sophisticated operating system than any version of the Macintosh System that was ever released.

In addition to the Lisa Office System, the Lisa hardware could run Xenix, (rumouredly) CP/M, and with the addition of MacWorks and a video modification, the Macintosh System.

The Lisa Office System desktop

The Lisa Office System provides a spatial graphical user interface. The desktop is not a glorified folder, but a place for items in use to be put, more like the RISC OS pinboard. Icons can be placed here for quick reference by dragging them from a folder window; alternatively, open documents can be 'set aside', which puts them onto the desktop in their unsaved state ready to be opened again later, or to be 'put away' back into their folder.

Windows in the Lisa system are far more strongly identified with their originating icon than even on the Macintosh. The small icon corresponding to the originating icon is shown in the top left hand corner of each window, and to save changes and collapse the window back down to its originating icon, the small icon is double-clicked. This is equivalent to choosing 'Save changes and put away' from the 'File/Print' menu. When a document is opened, its document icon changes to the 'opened' state (on the Macintosh, this icon state could only be seen on folders and applications, because the one document to one window rule was abandoned).

The 'Walrus' document is open

The Lisa system is far more document-centred than the systems that replaced it; and it is fair to say that conceptually, the concept of an 'application' as a way of creating documents does not exist in the same way at all. Every document must have a corresponding icon within the folder heirarchy; so there cannot be any such thing as an untitled document which does not yet have an on-disc presence (as a side-effect of this, there is no 'Save As' or anything like it, as this would mean that a window could become attached to a different icon in the course of its lifetime).

By the same token, there is no such thing as an active application; when a document's window is frontmost, the appropriate menus for that document are displayed, but there is no application launch or application switch. It is worth noting that this is only possible because, unlike the Macintosh System, the Lisa Office System has true multi-tasking.

Documents must be created from a stationery pad (a concept which reappeared to some extent in System 7). Each 'tool' provides an initial blank stationery pad (named 'LisaWrite Paper', 'LisaDraw Paper' etc.), and any document can be turned into a stationery pad by selecting 'Make Stationery Pad' from the 'File/Print' menu while the document's icon is selected. When a stationery pad is double-clicked on, a new document icon is created next to it, named after the name of the stationery pad and the date. This metaphor extends to folders too; initially, the 'Empty Folders' pad is used to create folders, and any folder can become a stationery pad.

Creating a new LisaWrite document

As an aside, the Lisa system does not appear to have any issue with having multiple files with the same name; and, conceptually, why should it? If the icon is the window is the document, the file name is simply a label used as a memory aid by the user in association with the icon and the spatial position of the icon.

Documents and folders can be password-protected; the password is set from the 'Attributes of...' menu item in the 'File/Print' menu (which is the equivalent to the Macintosh's 'Get Info' item). When a potected document or folder is opened, the system will ask for the password before opening it.

"Attributes of LisaWrite Paper 09/07"

Opening a protected document

It is possible to have tools that are not associated with documents; two examples of this are the clock and the calculator. To launch these, their icons can be double-clicked; but to show that they are not documents, the resulting windows have a different style of title bar with solid corners and solid black when active. This is a convention that was carried over to the Macintosh.

Desk accessories

If a document-centric tool is double-clicked on, then the tool tells you to tear off a piece of stationery.

Using the Lisa makes the choice of certain terminology in the Macintosh make more sense; the existence of the 'Put Away' menu item on the Macintosh to return an icon on the desktop to its original location is a feature for those who wish to use it in a Lisa-like fashion. Visually, the Lisa is less clear and well laid-out than the Macintosh; it feels considerably more cluttered, the icons are less ideographic and the fonts are less well-constructed. In terms of feel, however, the Macintosh feels less well-thought-through; it suffered greatly from being a single-tasking operating system, a constraint which must enforce a program-centric approach in user interaction with the system. By the time the Macintosh OS had gained some degree of multitasking with the MultiFinder, it was impossible to re-integrate the document model into the spatial interface; and in the MacOS X UI the spatial elements were effectively abandoned altogether.

Running MacWorks


by Rob Mitchelmore, 05:11 (anchor)
Thursday 30th August, 2007
Thoughts on user-land semantics for directed-graph filesystems: The filing systems associated with most modern operating systems are tree-like in nature: there exists a root directory which contains subdirectories, which contain subdirectories below them, and so forth (for the purposes of this writing, files do not exist; as they do not play an active part in the directory tree, they can be largely ignored).

This is an attempt to create a userland semantics for a roughly UNIX-like filesystem that nonetheless is a directed graph rather than a simple tree.

It is important to note at this stage that filenames in the UNIX filesystem are in fact not node names at all, but edge names. Files are uniquely identified by a node number on disc; and by that, every instance of a file in the filesystem has the same node number. However, every instance of a file in the filesystem can have a different name; see the following example:

~$ mkdir a b
~$ touch a/dugong
~$ ln a/dugong b/walrus

dugong and walrus are now two names for the same on-disc file; in other words, this part of the filesystem now looks like:


Fig. 1

Using the cd command to change directory is to traverse the named edge in the directory tree.

Early versions of UNIX did in fact have a directory graph rather than a directory tree (see Dennis Ritchie: The Evolution of the Unix Time-sharing System); this did not last very long, because it violated a principle herein called (in honour of Tom Stoppard) the Elsinore principle. It made much greater use of hard links than is customary in more recent iterations; notably because to change to a directory that 'contained' the current directory required significant contortions, which made the resulting filesystem considerably more difficult to use and incomprehensible than the tree-based version which succeeded it.

This leads to the statement of the Elsinore principle: that "every entrance is an exit somewhere else" - or, in other words, that doors or edges do not disappear once you have gone through them.

It is trivial to see that the tree-based UNIX filesystem adheres to this principle. The subdirectory relation defines two links between the directories involved, the named link, pointing from the parent to its subdirectory, and another called '..' pointing from the subdirectory to the parent. As soon as one of these edges is traversed, the 'door' remains visible in the form of the other. The UNIX filesystem is a tree so that users can backtrack through the path from which they came. How can this be done in the graph case?

A naïve approach which makes a lot of intuitive sense says to reserve a set of filenames (much as '.' and '..' are reserved), one for each parent. A sensible choice would be filenames beginning with the ^ character. If, in the above example, dugong were a directory rather than a file, its list might look somewhat like:

dugong$ ls -a
. .. ^a ^b
file.txt

This falls foul of the nature of the filesystem, however: in the UNIX filesystem, edges are labelled, and the parent directories have no inherent name. If the filesystem is a graph, any given directory could have any number of names. This would evidently be extremely confusing for the user, which leads us to another principle: people generally want to know where they are with more urgency than how they got there, and where they are going to be with more urgency than how they are going to get there.

This leads us to what will be referred to here as the Castle principle: name rooms in preference to doors. Name doors as well, if you so desire, but name rooms primarily.

In terms of physical spaces, this seems moderately obvious; going from an unknown place through a door to another unknown place, only to turn around and find that all the doors have been relabelled would be a deeply disorientating experience, and pity the poor user who steps through 'The ill-fated door of Sir Boris the Vertiginous' into a teetering mass of turretry, the only exit from which is directly downwards.

In software, where there are no 'physical' direction cues, this problem is exacerbated.

It should be noted that it is potentially useful to label doors; and so perhaps a 'relabel' command would be a useful thing to have.

Another point: whither '..'? Need we sacrifice this very useful convention?

To a great extent, this convention can be reinstated by storing the full path through which the current directory was reached as the current directory rather than just the node number of the current directory; this acts as a directory stack, where using 'cd' with an absolute path loads the stack from the pathname, 'cd' with a relative path pushes all elements of that path onto the stack, and .. refers to the directory reached through all nodes in the path except the very last. It is unclear how heavy a demand this would place on the computational or storage capacities of the computer, but it seems feasible.

This is only possible if the system contains the possibility of absolute paths; it can be argued (and has been by Jimmy) that if the filesystem is a directed graph, there is no need to have a 'root' directory, and rather base each user in their home directory. However, while backed by sound spatial reasoning (if the home directory of the user is identified with their desktop, then the 'visual' root of the screen corresponds to the conceptual root of the filesystem) this falls foul of the Castle principle, as places on the computer no longer have place names that are independent of the viewpoint of the user using it. In addition, the operating system needs to know where to find its own system files. It thus does make a good deal of sense to have a single 'root' point from which all edges are outgoing. Even the archaic UNIX graph filesystem had a similar concept to this; although it had no pathnames, every directory had a special 'dd' directory which linked to the directory of home directories.

That being said, why make a distinction between outgoing and incoming edges to a directory? The answer to this one is quite simple from a user's perspective; if all edges are equal then all recursive operations will eventually spread out to fill the entire filesystem, making most kinds of operations on directories at worst extremely space-hungry and marginally useless and at worst actively dangerous.

Some problems with this approach:

by Rob Mitchelmore, 04:08 (anchor)
Saturday 25th August, 2007
Some notes on Schenck's paintings 'Anguish' and 'The Orphan'.
by Rob Mitchelmore, 20:50 (anchor)
Tuesday 31st July, 2007
Noun cases should be represented ideographically within computer user interfaces: the command line as it stands is a peculiarly English system, relying as it does upon word order and putting great importance on the verb. It also requires you to know what you want to do before you do it. In a case-driven interaction system, the nouns and verbs could be specified in any order, distinguished by their case-markers. These, as previously suggested, could be ideographic icons; they could also be colours (ideas heading in this direction can be found in Chuck Moore's colorForth language), by plain-text conventions (possibly akin to perl's use of @ and $ for 'plural' and 'singular') or in some peculiar cases with case endings from the 'host' natural language.

This is heading in similar directions to some of the work Jimmy has done; one question is how to decide which set of cases is necessary and sufficient to describe the set of operations the system provides. Should applications be able to define their own?

This does not affect the UNIX pipe, and and or operations and others like them, as they are conjunctions; the input and output redirection operators, however, would become shortcuts for a pipe, the verbs 'read', 'write' or 'append' and a locative or ablative noun.

by Rob Mitchelmore, 03:26 (anchor)
Sunday 15th July, 2007
Mornington Crescent: a transcript of a game played by Tom Isaac and Rob Mitchelmore between the 10th-14th July 2007 online, provided here for study. Millar's 2007 tricycle rules are in play:

Stations with three circles count double, unless one of them is DLR in which case you forfeit the ability to ask for a hawk-eye linecall on Liverpool street.

Tom Isaac is to start play.


Fulham Broadway.
Oh dear, I'm a bit rusty at these rules. OK...

I shall play Kilburn.

Hmmm....

Notting Hill Gate.

Willesden Park.

(opening the westernmost helix)

Hammersmith.

I think I'm getting dangerously close to falling in to the left-side backhand pass trap.

It is unkind of you to take advantage of my insomnia; that said, yes, you are dangerously close. Thus:

Farringdon

oooohhh. nasty. Bank.
(Hang on, hang on. Was that a tricycle I saw heading in my direction? But Bank already counts double according to Cryer (consult page 271, the little paragraph at the bottom) because it has two names. Doesn't it?

Does this mean I get four goes? I'm so confused...)

(Ah, but then Bank's got a fourth circle on the DLR with wheel chair access. So I make that a total of eight wheels including the little castor-type wheels on your standard issue wheelchair, which is 2.666666etc. tricycles. So I think you get as many goes as I have typed recurring sixes. It is Tuesday right?)
It is Tuesday, yes, so the Fourier rule applies for orthogonalisation of tricycles... now there's a clause in the rules I didn't expect to have to use.

Since it's a recurring decimal, I'll go around South Kensington - Victoria - Green Park; as moves map 1:1 onto natural numbers, the set is countably infinite (see Cantor), thus it's your go again.

As a gesture of goodwill, I'm going to remind you that moving to inside an infinitely recurring icoseles triangle puts you non-negotiably in Nid. (As opposed to an infinitely recurring equilateral triangle, which doesn't, or an infinitely recurring scalene triangle, which is just downright rude)

Gah, infinite set theory at this stage of the game! ponders, leans on point of an isoceles triangle, bleeds Err... Doesn't that put M. C. somewhere in to the uncountable set of all the real numbers? Hmmph. Well I'm going to start climbing this asymptote and theoretically end up at Canary Wharf. Your move! (And please be kind, I'm a physicist, Maple does all my mathematics for me!)
It sounds kinda complex to me. It's not so much important whether it is in the set of reals as whether it is in the set described by the metric. Millar gives a transform on
z' = z2 + c
and as such, I refer to you to the following diagram:

As you can see, the horizontal axis of the set is aligned at the left on the central line with the far lobe on White City, and on the rightmost side the central line and DLR are nearly symmetrical. The leftmost major lobe is described by the pair (Baker Street, Picadilly Circus) and the far lobe by (Dalston Kingsland, Canada Water) (sigh).

By plotting it one can trivially see that MC is within the ending conditions for the game.

With this in mind: Royal Oak.

Rob, I hereby officially award you man of the match for overlaying a fractal on to the Tube Map in a game of Mornington Crescent.

And I shall take advantage of this chaotic twist to the game and bifurcate. Maida Vale AND Kennington.

Now it's getting difficult. Fortunately I can control the decay by playing a parallel:

Hatton Cross and Hammersmith.

Swapsies: Kennington and Maida Vale
Going round a little dollis hill loop all your own?

Finsbury Park, Kentish Town, Swiss Cottage AND Harrow & Wealdstone

OK, now cashing in all the tricycles from earlier, bifurcating three times and breaking causality a bit:

The continuum of all stations between West Ealing and Embankment on the District line, excluding St. James Park.

The Circle line.

If we keep on going like this we're going to get to M.C purely by default you do realise.

Ah hu - Zones 1 & 2. Ergo, Mornington Crescent. And I think my Oyster card has exploded :-)

Tom Isaac wins.

Aftermath:

'Tricycle is one of my favourite rulesets as there are actually only two stations with three circles on the standard map - but on newer editions Bank has a separate, fourth wheelchair access circle. Compare http://www.bbc.co.uk/london/travel/downloads/tube_map.html and http://www.metro-map.ru/world/img/london_print_map.pdf. Knowing Rob was likely an oldschool M.C. player I took a gamble that he might be using the old map. Of course this all backfired once he found the footnote in Cryer that threw Bank straight back at me."

'After that the algebra got a little heavy and I had to consult my rusty Pure Math from back in the day. But Rob rather sportingly handed me a clue in the shape of that fractal-map, and when things get chaotic, he who forks first forks most. In this case it was me.'


— Tom Isaac


'I was hampered by being unfamiliar with the Millar rules; fortunately his style is seated deep in the traditional nature of the game rather than the more recent and (by most objective measures) ridiculous postmodern variants. The increased importance of tricycles makes the game dynamic considerably more complicated as the upper bound on the number of foci in play is raised dramatically.'

'If Tom's loop had gone anticlockwise rather than clockwise, after his station-continuum move, I could have played the Northern line and won; but alas that option was closed off from me. Had I been more familiar with Millar I'd have played a virtual Waterloo as we were already in the complex plane; this could have been played without penalty so long as I returned the train to the point I had got it from sufficiently rapidly. Unfortunately I didn't think fast enough, so failed to control the bifurcation and lost the game.'

'It could have been much worse; I was expecting Tom to head over towards Heathrow, where the ending of the game would have entirely depended on how many wheels (in aggregate) that day's flights had attached to them.'


— Rob Mitchelmore

by Rob Mitchelmore, 04:46 (anchor)
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