Linux Toshiba Libretto 70 "Retro Mediaplayer" 1/2010

By
Greg Menke
gmlathe@comcast.net



My brother and I have a little game we play when we happen to be travelling together;

- observe the license plates of surrounding cars, looking for those which have three letters amidst the numbers.  The letters need not be adjacent- some states have the letters grouped, others don't.

- given the three letters, find words that use all three in the order shown on the plate, but not necessarily adjacent each other

For example; the license plate "PRL 123" yields the letters P,R, and L- one word in which they are used in order is "parallax", "prelate" is another.

To help discover words that we were unable to think of quickly, I wrote a program to search several word lists, find matches and display them.  I named it "Wordfiend" or wfiend, it is described in more detail below.

A laptop is a convenient platform for this sort of application. Its preferable to have something really small w/ a keyboard, running Linux so its easy to maintain and manage.  So I got a Libretto 70.  wfiend is set up to run on virtual terminal 0, at bootup.  This way, all I need to do to play it is turn on the Libretto.  Once booted, wfiend is ready to go.

Overall

Libretto's are nice, but getting an OS onto them is tedious.  PCMCIA floppy drives exist, but they always seem to be more trouble than they're worth.  My preference is to put the Libretto's hard disk in a larger (faster) laptop with a cdrom, install Linux, then move the disk back into the Libretto.  There are a couple nuances;

- The Libretto uses a fairly ancient Pentium cpu- i586 as far as Linux is concerned.  The candidate distro must offer an i586 target, this likely precludes many of the modern binary distros- the install must be targetted to the Libretto's cpu, not the host computer's.

- The host "laptop" (likely being newer) may use /dev/sda for the hard disk, whereas the Libretto uses /dev/hda.  This isn't a big problem because you can edit /etc/grub/grub.conf and /etc/fstab before transplanting the hard drive back into the Libretto.  Ideally, the host laptop (or PC) would be old enough to use /dev/hda, so the issue won't arise.

- A modern SATA laptop will not work- you have to be able to install the PATA hard disk.  Alternatively, adapters that permit connecting the laptop hard disk to a PC motherboard's PATA connector are common, so you can host the Libretto's hard disk in a regular PC for the Linux install.

- when partitioning the Libretto's disk, you should consider leaving space unallocated where APM suspend writes the memory image.  If you don't reserve the space and suspend the Libretto, that chunk of your filesystem will be summarily overwritten.

The sections below detail configuration settings I put in place to set up the Libretto how I like it.  Tastes vary, so these might be a good starting point.  The entire tree containing the files referenced below starts here.



/etc/fstab

(link to fstab)

the disk partition is as follows;

Disk /dev/hda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x5f8d7688

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1           5       40131   83  Linux
/dev/hda2               6          22      136552+  82  Linux swap / Solaris
/dev/hda3            1170        9713    68629680   83  Linux

Note the holes left both at the end of the disk, and below cylinder 1024.  From various google references it sounds as if the Libretto's BIOS suspend function writes to cylinders below 1024, so I left them open- but also those at the end of the disk in case it writes there.  This leaves something like 20gb of the disk unavailable, if I get to a point where I'm running out of space then I'll track down where the writes actually go and reconfigure the partitions to be more efficient.



Kernel

Because its so easily tailored, I used Gentoo Linux.   I prefer Fedora but it would not boot on the Libretto, its i586 target was too new apparently.  Regardless of distro, with the Libretto disk in the host computer and the install completed, a kernel should be compiled, tailored to the Libretto.  This kernel is configured to be fairly minimal, but it does include PCMCIA (including PCMCIA lanboard drivers), audio, APM, and the IP stack.

Linux wfiend 2.6.27-gentoo-r7 #13 Sat Jun 20 17:53:12 EDT 2009 i586 Pentium MMX GenuineIntel GNU/Linux

(link to .config)

(link to /boot/grub/grub.conf)


Daemons, applications

As much software as possible should be installed with the disk in the host computer- otherwise you'll probably be compiling for days and some apps won't compile at all due to lack of memory.  This isn't a problem if you happen to use a binary distro with a suitable target, but is when using Gentoo.

/etc/make.conf for my Gentoo installation
(link to /etc/make.conf)

As far as daemons are concerned, ssh, nfs, ntp are helpful.  Since the Libretto 70's performance is modest, its helpful to have the network related demons NOT start by default (saves memory and boot-time when the unit is not going to be connected to a LAN, which for me is most of the time).  But when connection to a network is intended, a PCMCIA lan board is inserted and the appropriate daemons are started manually.  This usually means sshd, which allows the user to log in from a PC which offers a much more convenient keyboard and display.

I also found it helpful to leave the ntpd turned off, and instead issue 'ntpdate' manually when the Libretto is on the network.  If you allow its battery to run out, the system will lose its calendar time.  That doesn't present a problem as far as wordfiend and the mediaplayer, but is annoying when you intend to compile/maintain/install software- ntpdate is a simple one-step command you can run when you need it.



/etc/inittab

I modified /etc/inittab to automatically login to various of the virtual terminals, avoiding the tedium of typing accounts and passwords on that tiny keyboard.  As it happens, this was very helpful for the Retro Mediaplayer- since a mixer can be started on one virtual terminal while in another the media player resumes to where I previously had paused & suspended.  It also avoids the problem of forgetting passwords if you don't use the computer for a while.  Security of the computer isn't of much concern (in my application at least), since without a USB port, cdrom or network nothing much is going into or out of the Libretto and I don't keep anything important on it.

(link to inittab)

The following .bashrc handles starting the applications on a per-virtual terminal basis

(link to .bashrc)



Suspend/Resume

To suspend the Libretto, I wrote a little script '/rc.suspend' which handles the details of initiating an APM suspend, and upon wakeup, reconfiguring the sound and hdparms.  If the hardware reconfig is not done, the soundboard will produce noise and the hard disk interface will be slow.  To run the script, I installed sudo and configured my user account as NOPASSWD: ALL- thus "sudo /rc.suspend" can be invoked from anywhere.

(link to rc.suspend)



Sound

I chose to use Alsa for sound.  The configuration I used is;

options snd-opl3sa2 enable=1 isapnp=0 port=0x370 sb_port=0x220 wss_port=0x530 fm_port=0x388 midi_port=0x330 irq=5 dma1=1 dma2=0


Mouse

I found 'gpm' picks up the onboard mouse as PS/2 with no trouble.  I usually leave the daemon off since the cursor is susceptible to inadvertent select and paste when grabbing the Libretto's lid, where the mouse buttons are.



Video

I installed X with my preferred desktop (WindowMaker).  It runs fine but the display being so small and cpu so slow, using a gui requires patience.  For one thing, the mouse buttons and "eraser" pointer make window focus problematic.  Here is the xorg.conf;

(link to xorg.conf)

I did have success using 'dillo' as a web browser, though getting the font sizes under control so webpages can be browsed was difficult.  Mozilla/Firefox are far too large to run efficiently on a 32 meg Libretto 70.



Userspace

Having the Libretto working and configured, I installed the wordfiend and player software.  With respect to writing and maintaining software for the Libretto, a cm system such as cvs or svn or equivalent is extremely helpful.  The software can "live" on a local Linux box, maintained and enhanced there- and whenever the Libretto is connected to the local network, the older revisions on it can be updated trivially. 

I also have a 64 meg Libretto 100, which is substantially faster and uses nearly the exact same configuration.  In fact I can move the hard disk from the 70 to the 100 and it works fine.  The X-Windows driver is different, however the 100's faster cpu and additional memory are advantageous- and I prefer its keyboard & display.  I'd switch to the 100 but do not have a good battery or a power adaptor for it, both of which I have for the 70.


Wordfiend aka wfiend

located in /home/wfiend/wfiend

(link to files)

wfiend is a Common Lisp application.  It accepts one or more characters on the command-line (case insensitive), searches its word lists and produces a set of matches.  A match is defined as a word that uses each of the three letters, in order but not necessarily adjacent to one another.  Each match is given a score.  The score is the reciprocal of the standard deviation of the number of characters between each of the matching characters.  I call it the "dispersion" score.  The higher the score, the more evenly the matching characters are distributed amongst the other characters forming the word.  If the standard deviation == 0, then an arbitrary perfect score of 1,000,000 is given.  As it happens, perfect scores are relatively rare so an artifically high perfect score causes the word to jump out of the list of other matches.

The effective value of a match is primarily dependent on its subtlety, with dispersion as a secondary factor.  Seeing the license plate "DOG 999" and yelling "dog" is worth little even though it has perfect dispersion, however given "KGB 999" and deducing "packageable" or "mockingbird" in real time is an overwhelming victory regardless of dispersion.  Dispersion is a reasonable way of scoring words that are viewed as similarly "good".

Scrabble rules are used to specify acceptable words.  Generally, matches that use prefixes or suffixes are not preferred, although they are acceptable, moreso when a given set of letters produces few matches.

Dispersion is something of an aesthetic score, another score based upon the frequency of use would be a useful enhancement.  Possibly, dispersion could be one axis and frequency (sans prefix and suffix, lower frequency is better) another, the total score being the area described.  The perfect dispersion score would have to be redefined, and frequency would have to be strengthened relative to dispersion.  I have downloaded some word frequency tables, but haven't implemented the "frequency" score yet.

With respect to word lists, I found and downloaded the "12dicts" and SIL International's "wordsEn.txt" English lists, both available on the Internet.  Handily, they include variations of words due to prefixes and suffixes, so wfiend doesn't have to do any extra work testing for them.  Obviously these lists are not exhaustive, but they are good for this purpose.  Certainly good enough for etymological sparring whilst on the road.

I wrote and tested wfiend using CLISP (an open source Common Lisp), but the search is too slow on the Libretto (approx 40 secs).  Compiling wfiend using CMUCL improved performance considerably.  I had the best results by compiling wfiend in Lispworks, then copying the executable onto the Libretto.  This approach requires about 7 seconds to perform a search, which has proved adequate.

Implementation-wise, wfiend does a brute-force search of the lists, scores each match and produces two lists, one sorted by word, the other by score.  Thus, a word can be found and evaluated either way- helpful when a set of letters yields many matches.  The search algorithm has to find each letter of the search "vector", wherever it exists in a candidate word, so checking for a match amounts to several substring searches, one for each character, starting from the position of the previous character's first match.  A brute force search was the easiest to implement, and not prohibitively expensive in cpu time or index space, so I didn't develop it further.


Retro Mediaplayer aka player

located in /home/wfiend/player

(link to files)

(link to rc.book)

This is another Common Lisp application, written using CLISP.  This app does not present performance issues since the actual media playing is done by mpg123, which player invokes.  player's function is to present a very simple and useful menu to control playing "long" media such as ripped books-on-cd.  It keeps a book's "state" (which file of the set of files is being played, and the # seconds into that file) so a book can be resumed later (even much later).  Since each book has its own state, any number of books can be in progress.  My usual procedure is to buy a book-on-cd, rip the tracks to mp3 files and put them on the Libretto in a subdirectory which is given the book's name, beneath ~/books.  The original media is stored as a backup.  Thus, the directory  "~/books/right-ho-jeeves" contains the mp3 files comprising that audio book.

A book is played via "~/rc.book ~/books/[bookname]" where [bookname] is the subdirectory in which the book's mp3 files are located.  When the player is stopped (perhaps to suspend the Libretto), the state is saved to a text file named after the book's name.  To resume playing the book, the command is re-run, the text file is read, and the player continues from where it was stopped.  Since the book state is in a file, resuming the book is not dependent upon suspend/resume or restarts.  player saves state every 1000 audio frames, so if the app terminates (perhaps the Libretto runs out of battery and turns off), then playback can be resumed from a point not too far before the power-off.

player offers the usual sort of commands Pause, Quit, start Next file, start Previous file, forward/rev the current file and Suspend.  Suspend pauses the playback, then invokes /rc.suspend- a convenient way to stop playing the book and have the Libretto turn itself off.  Later, when the Libretto is unsuspended, player will be back where it started and playback is easily resumed.

When player scans the directory containing the book's files, it acquires a listing of all the mp3 files present and sorts them in alphanumeric order.  The mp3 files should be named so they end up in the proper order.  That usually means ensuring things like cd numbers and track numbers are two digits (ensure the 2nd disc is named 'disc-02' so that 'disc-10' does not sort before it).

One advantage of player is that when it is not actually playing, the audio device is not held open.  This permits the suspend/resume logic to work in a simple manner, and avoids interference with other audio players.  Although player will work fine for shorter mp3's such as music files, it will not shuffle.  In such an application it will remember which song was in progress and will work its way through an arbitrary number of songs, but skipping forward/backward within a song is unlikely to work conveniently.

Note- player does not yet properly handle the case where it is playing and suspend is initiated elsewhere.  In such a case, when resumed, garbled sound will be produced until the file being played is restarted or player Quit.


;;; eof


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