Mike Meredith

What Is A Dumb Terminal?

 Computing, History  No Responses »
Jul 302023
 

Ah yes! Well the first thing to answer is what a terminal is.

A terminal is a device for communicating with text (graphics was possible but relatively rare especially in the early days) with a computer – you would type in a command in text and the computer would respond in text :-

» ls
1  2  bad-directory

Although the “terminal” is still available today in the form of a gooey program, the early terminals communicated with the computer with some form of serial port (usually RS232). The first terminals were modified teleprinters (often called “Teletypes” due to the domination of that company in the USA). These were large electromechanical devices where the display was paper – they were printing terminals.

The first terminals that displayed on a screen were very much like the printing terminals – they would “print” output from the computer on the last line of the screen and scroll for additional lines. Just like on a printing terminal except that once things scrolled off the top of the screen they were lost.

At this point in computing history, we’re just at the start of the microcomputer age; in fact one of the uses for which Intel’s second processor (the 8008) was developed was to operate as the heart of a computer terminal.

As the microprocessor controlled terminal was essentially run by software, programmers started adding in new features that would do things like clear the screen, move the cursor around the screen so you could display text anywhere you wanted.

At this point one definition of “dumb terminal” can be found – a terminal that just emulated a printing terminal was a dumb terminal; ones with additional features weren’t so dumb.

As the 1970s progressed, terminals gained more and more features and eventually some became capable of downloading software from the computer they were connected to and running that software locally. Such as (optionally) the HP 2647. Or the Bell Labs blit terminal.

Such terminals could be termed “smart” and their predecessors “dumb”. And if you notice a similarity with the somewhat later “thin clients“, you wouldn’t be entirely wrong.

Alternatively, some terminals (such as the IBM “green screen” terminals) operated in block mode where the terminal would allow a certain amount of editing within the terminal and send the result back to the computer a screen at a time. These necessarily had to have a certain amount of “smarts” built in, so they were smarter than character at a time terminals (thus “dumb”).

"Dumb" Terminal
A “dumb” terminal

So to an extent there is no real agreement on what a “dumb terminal” really is. Pick one that you like!

A Word To The ULEZ Whiners

 General, Politics  No Responses »
Jul 302023
 

Or perhaps more than just a word given the level of dumbness displayed by the usual ULEZ opponents.

  1. It isn’t solely a Labour policy; the ULEZ zone in central London was first introduced by a Tory major (Boris Johnson) and extended by the current Labour major. The Tory opposition to ULEZ during the Uxbridge by-election was a cheap political stunt to distract from the atrocious record the Tories have in central government. Which seemingly worked on the more gullible.
  2. The penalty charge for the ULEZ zone is only paid by the most polluting vehicles – diesel cars older than 8 years old and petrol cars older than 17 years. Which is a tiny minority of the cars on the road.
  3. This isn’t targeting the poor; the poor in our society can’t afford cars at all. Besides there’s a scrappage scheme which pays people to scrap the smellier cars.
  4. This isn’t about CO2 emissions; it’s about NOx emissions.
  5. And frankly none of the objections (even if real) come close to outweighing the advantages of fewer deaths from pollution.
Ceci n’est pas une cabane de plage

Was The House Of Wessex “Welsh”?

 History  No Responses »
Jul 112023
 

Well, not “Welsh” but Brythonic. The Anglo-Saxon royal dynasty called the “House of Wessex” was supposedly founded by a certain Cerdic. The interesting thing about this character is that his name is Brythonic in origin, and of course that he defeated a Brythonic king to take his territory.

Now if we skip a few centuries to when the Anglo-Normans invaded Ireland, the Norman mercenaries were invited by a certain deposed Irish king – Diarmait Mac Murchada. A not uncommon solution for a king having been deposed was to try and raise an army to take the kingdom back, and if you have plenty of cash, mercenaries may well be part of that army.

There is no evidence for this, but what if Cerdic was a deposed Brythonic king, or a disgruntled Brythonic noble who hired a bunch of germanic mercenaries. And if he had offered them land as well as gold, that could easily explain how a bunch of Saxons ended up living here.

Which may go some way to explaining why the Brythonic people didn’t really disappear but got absorbed over the centuries.

It’s a crazy idea and there’s no evidence for it. But it’s an interesting hypothesis.

The Round Table

Resurrecting Messiah Craze

 History, Music  No Responses »
Jun 112023
 

No, not that one (no disrespect to Native Americans intended); rather a small band from Swansea around in the late 1980s. That’s where I went to university and I was rather a fan and saw them numerous times live. I also have a tape they released privately which I’ve been unable to listen to for many years.

So I “resurrected” it, and this post is to document how it was done :-

  1. Obtain a tape player and connect it to your computer’s “Line In”. In my case an old Sony TC-TX515 (which is good enough for this purpose).
  2. Fire up Audacity
    • Set the input device appropriately.
    • Set the bit depth to 24 bits (the default of 32 can be problematic with some tools).
  3. Fire up gtk wave cleaner
    • Detect clicks.
    • Detect songs
    • Use the song markers as a guideline for selecting tracks (in the bottom so you get both left and right channels) and saving each individual track as a WAV file.
  4. Convert each individually to a flac file :-
    • flac -o 01_track.flac 01_track.wav
  5. Add meta information :-
    • Add replay gain (optional): metaflac --add-replay-gain *.flac
    • Add individual tags: metaflac --set-tag=TAG="Value to set" 01_track.flac. The tags set for each track were: TITLE, ALBUM, TRACKNUMBER, ARTIST, GENRE, and DATE.

The first side of the tape came out surprisingly well; the second not so much (which is why it is not included below) as it was a live recording from the Mandela Bar (every student had a Mandela Bar to visit in the 1980s).

I’m going to link to a ZIP file containing the tracks from the first side of the tape. The music remains copyrighted by the band :-

  1. Tony Brown
  2. Mark Holownia
  3. Richard Jouault
  4. Dusty Kennedy
  5. Steve Leatherdale
  6. Andrea McCulloch
  7. Tony Skiller

If any of those have objections to their music being distributed like this, please contact me.

As to the ZIP file, it’s available here.

And just for once an almost relevant picture …

Do You Need A Separate /home Partition for Linux?

 Computing, Linux  No Responses »
Jun 112023
 

Ah yes! The eternal debate on how to do storage under Linux (and previously Unix). This debate has been going on since Unix found itself with some disks.

No, but …

First of all, in the simplest case of installing Linux onto a machine with a single disk isn’t the only possibility here. If you are in that situation, you do need to consider a separate partition for the /home file system.

But there are all sorts of other possibilities here – for example my own workstation has a separate /home file system but it comes from another (ZFS) storage pool of disks. So my system disk doesn’t have a separate partition for /home. If you are using extra disks you’ll almost always want a separate /home file system.

But before we get too deep into the technical terms, what exactly are they?

  1. When setting up a new disk, you can divide it up into 1 or more partitions which to the operating system look pretty much like disks – you can use nvme0n1 to create a file system, or you can use nvme0n1p1. On a system disk you will very often have three or more – one each for /boot, /boot/efi, and / (at the least).
  2. Once Linux has taken over a disk and “formatted” it for its use, it has a data structure on it that makes it a file system of one type or another. This file system can be mounted at any point in the hierarchy, so historically (when we had much smaller disks), there could be file systems mounted at /, /usr, /var, /var/spool, /usr/local, etc.

So do we need a separate /home file system? Of course not, but that doesn’t mean it isn’t a wise thing to do.

If you’re setting up a throw-away laptop that won’t ever store anything important, then sure a separate /home file system is probably a waste of time – it’ll probably only ever store some configuration files. If the system you’re setting up is your main machine and /home contains all your files – past, present, and future, then a separate /home file system is worth considering.

  1. If you ever re-install the operating system, your separate /home could be preserved so that you don’t have to restore from backup. That isn’t safe (so you should always have a backup elsewhere) but it can be done fairly easily (with enough practice).
  2. If you upgrade your storage, a separate /home file system can be quicker and safer to copy (at the file system level) to the new storage. Doing it on a file-by-file basis (such as with the excellent rsync) is likely to be very much slower than doing it at the file system level (such as with zfs send).
  3. It should be a great deal easier to take important backups if all the important files are on one file system.
Peering At Each Other
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