gkmac
@gkmac.bsky.social
Part-time teletext and retrotech dabbler. Maker of QTeletextMaker.
Were colour bitmap graphics possible in #teletext ?
With Level 3.5 DRCS they could have been. But hopelessly impractical; all the bitmap data is stored across 8 subpages and you'd need to wait for them all to come around.
Just for that one picture that's the biggest size possible in 16 colours.
With Level 3.5 DRCS they could have been. But hopelessly impractical; all the bitmap data is stored across 8 subpages and you'd need to wait for them all to come around.
Just for that one picture that's the biggest size possible in 16 colours.
November 12, 2025 at 6:46 PM
Were colour bitmap graphics possible in #teletext ?
With Level 3.5 DRCS they could have been. But hopelessly impractical; all the bitmap data is stored across 8 subpages and you'd need to wait for them all to come around.
Just for that one picture that's the biggest size possible in 16 colours.
With Level 3.5 DRCS they could have been. But hopelessly impractical; all the bitmap data is stored across 8 subpages and you'd need to wait for them all to come around.
Just for that one picture that's the biggest size possible in 16 colours.
QTeletextMaker v0.8-beta released. The Level 2.5 #teletext editor now renders DRCS characters and slightly improved diacritical'd G0 capital letters.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with #Qt6 and CMake.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with #Qt6 and CMake.
October 14, 2025 at 3:53 PM
QTeletextMaker v0.8-beta released. The Level 2.5 #teletext editor now renders DRCS characters and slightly improved diacritical'd G0 capital letters.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with #Qt6 and CMake.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with #Qt6 and CMake.
As if black foreground wasn't controversial enough, should modern Level 1 and 1.5 #teletext decoders obey the double width and double height control codes?
The ETSI spec says they are Level 2.5 only, but in real life some Level 1 and 1.5 decoders made since about 1999-ish do interpret them.
The ETSI spec says they are Level 2.5 only, but in real life some Level 1 and 1.5 decoders made since about 1999-ish do interpret them.
October 2, 2025 at 9:21 PM
As if black foreground wasn't controversial enough, should modern Level 1 and 1.5 #teletext decoders obey the double width and double height control codes?
The ETSI spec says they are Level 2.5 only, but in real life some Level 1 and 1.5 decoders made since about 1999-ish do interpret them.
The ETSI spec says they are Level 2.5 only, but in real life some Level 1 and 1.5 decoders made since about 1999-ish do interpret them.
Ahh, good old #teletext with no cookie pop-ups, no registrations or sign-ins, no autoplaying videos... and no sudden geo-blocks either.
September 30, 2025 at 6:33 PM
Ahh, good old #teletext with no cookie pop-ups, no registrations or sign-ins, no autoplaying videos... and no sudden geo-blocks either.
For the upcoming #ChunkyFringe the #WeeklyTeletextArt prompt is "Chunky" and/or "Fringe".
Here's a #teletext nod to an old chocolate advert; regrettably trademarks have had to be altered for legal reasons.
Here's a #teletext nod to an old chocolate advert; regrettably trademarks have had to be altered for legal reasons.
September 28, 2025 at 5:50 PM
For the upcoming #ChunkyFringe the #WeeklyTeletextArt prompt is "Chunky" and/or "Fringe".
Here's a #teletext nod to an old chocolate advert; regrettably trademarks have had to be altered for legal reasons.
Here's a #teletext nod to an old chocolate advert; regrettably trademarks have had to be altered for legal reasons.
My first ever attempt at getting a Level 2.5 #teletext DRCS bitmap onto a real TV!
24 monochrome characters is the maximum you can have on screen; the bitmaps (or Pattern Transfer Units as they're called) are downloaded from a separate hidden page.
DRCS rendering in QTeletextMaker coming soon...
24 monochrome characters is the maximum you can have on screen; the bitmaps (or Pattern Transfer Units as they're called) are downloaded from a separate hidden page.
DRCS rendering in QTeletextMaker coming soon...
September 21, 2025 at 6:14 PM
My first ever attempt at getting a Level 2.5 #teletext DRCS bitmap onto a real TV!
24 monochrome characters is the maximum you can have on screen; the bitmaps (or Pattern Transfer Units as they're called) are downloaded from a separate hidden page.
DRCS rendering in QTeletextMaker coming soon...
24 monochrome characters is the maximum you can have on screen; the bitmaps (or Pattern Transfer Units as they're called) are downloaded from a separate hidden page.
DRCS rendering in QTeletextMaker coming soon...
There's nothing that divides #teletext enthusiasts more than whether or not black foreground attributes should be interpreted on Level 1 decoders. ETSI spec says they shouldn't, in real life all decoders made since about 1990 do.
The test below shows the problems that can happen on old decoders.
The test below shows the problems that can happen on old decoders.
June 21, 2025 at 11:51 AM
There's nothing that divides #teletext enthusiasts more than whether or not black foreground attributes should be interpreted on Level 1 decoders. ETSI spec says they shouldn't, in real life all decoders made since about 1990 do.
The test below shows the problems that can happen on old decoders.
The test below shows the problems that can happen on old decoders.
QTeletextMaker v0.7.2-beta released. The Level 2.5 #teletext editor can now import & export pages in EP1 and HMS datastream htt formats in addition to the existing TTI and t42 formats.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... or compile the source on Linux with #Qt6 and CMake.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... or compile the source on Linux with #Qt6 and CMake.
March 30, 2025 at 1:24 PM
QTeletextMaker v0.7.2-beta released. The Level 2.5 #teletext editor can now import & export pages in EP1 and HMS datastream htt formats in addition to the existing TTI and t42 formats.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... or compile the source on Linux with #Qt6 and CMake.
Grab a Windows exe from the zip at github.com/gkthemac/QTe... or compile the source on Linux with #Qt6 and CMake.
A Level 2.5 #teletext parody of the original Microsoft Store handbag icon.
The blue-to-black gradient is only there to hide the held mosaics that allow the top corners of the handle to be different colours, then I went a bit overboard with nested Objects to implement a real vertical gradient.
The blue-to-black gradient is only there to hide the held mosaics that allow the top corners of the handle to be different colours, then I went a bit overboard with nested Objects to implement a real vertical gradient.
January 22, 2025 at 1:23 PM
A Level 2.5 #teletext parody of the original Microsoft Store handbag icon.
The blue-to-black gradient is only there to hide the held mosaics that allow the top corners of the handle to be different colours, then I went a bit overboard with nested Objects to implement a real vertical gradient.
The blue-to-black gradient is only there to hide the held mosaics that allow the top corners of the handle to be different colours, then I went a bit overboard with nested Objects to implement a real vertical gradient.
QTeletextMaker v0.7-beta released. The Level 2.5 #teletext editor can now export your flashy masterpieces to animated GIFs so they can stay flashing!
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6 and CMake.
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6 and CMake.
January 12, 2025 at 8:25 PM
QTeletextMaker v0.7-beta released. The Level 2.5 #teletext editor can now export your flashy masterpieces to animated GIFs so they can stay flashing!
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6 and CMake.
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6 and CMake.
2/2 and here's the Level 1 version.
January 10, 2025 at 9:47 PM
2/2 and here's the Level 1 version.
1/2 Now that BlueSky animates your own uploaded GIFs, a Level 2.5 #teletext tribute to one of the earliest internet memes from the year 2000.
A website "Flash intro" that promised everything but delivered nothing. zombo.com is still there, updated to HTML5 but still with the original soundtrack.
A website "Flash intro" that promised everything but delivered nothing. zombo.com is still there, updated to HTML5 but still with the original soundtrack.
January 10, 2025 at 9:46 PM
The #weeklyteletextart prompt this week was "spaceship".
So here's a re-posting of a #teletext recreation of the final level of the shoot-em-up arcade game "Phoenix", featuring one of the first examples of an end-of-game boss.
So here's a re-posting of a #teletext recreation of the final level of the shoot-em-up arcade game "Phoenix", featuring one of the first examples of an end-of-game boss.
December 14, 2024 at 10:25 PM
The #weeklyteletextart prompt this week was "spaceship".
So here's a re-posting of a #teletext recreation of the final level of the shoot-em-up arcade game "Phoenix", featuring one of the first examples of an end-of-game boss.
So here's a re-posting of a #teletext recreation of the final level of the shoot-em-up arcade game "Phoenix", featuring one of the first examples of an end-of-game boss.
QTeletextMaker v0.6.5-beta released. The Level 2.5 #teletext editor now has monochrome rendering modes so you can see what sixels are foreground and background.
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6.
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6.
December 4, 2024 at 12:58 PM
QTeletextMaker v0.6.5-beta released. The Level 2.5 #teletext editor now has monochrome rendering modes so you can see what sixels are foreground and background.
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6.
Grab a Windows .exe from the zip at github.com/gkthemac/QTe... (mind the SmartScreen warnings!) or compile the source on Linux with Qt 6.
Thinking outside the box for the #WeeklyTeletextArt "pirates" prompt.
Taking classic Level 1 #teletext decoders into account with "safety" foreground blue so the black foreground doesn't get hidden, and "safety" double height so ignored double size doesn't leave a spurious black stripe.
Taking classic Level 1 #teletext decoders into account with "safety" foreground blue so the black foreground doesn't get hidden, and "safety" double height so ignored double size doesn't leave a spurious black stripe.
November 10, 2024 at 10:05 PM
Thinking outside the box for the #WeeklyTeletextArt "pirates" prompt.
Taking classic Level 1 #teletext decoders into account with "safety" foreground blue so the black foreground doesn't get hidden, and "safety" double height so ignored double size doesn't leave a spurious black stripe.
Taking classic Level 1 #teletext decoders into account with "safety" foreground blue so the black foreground doesn't get hidden, and "safety" double height so ignored double size doesn't leave a spurious black stripe.
And here's how NOT to use side panels! This Level 2.5 #teletext rendition of "Night Mail" by W.H.Auden uses an additional 8 character columns for the content itself, which will never be shown on a Level 1 decoder!
October 16, 2024 at 2:21 PM
And here's how NOT to use side panels! This Level 2.5 #teletext rendition of "Night Mail" by W.H.Auden uses an additional 8 character columns for the content itself, which will never be shown on a Level 1 decoder!
An interesting legitimate use of a side panel seen on an actual #teletext service. Here it keeps an index of pages on the left side of the screen.
October 16, 2024 at 2:19 PM
An interesting legitimate use of a side panel seen on an actual #teletext service. Here it keeps an index of pages on the left side of the screen.
Level 2.5 #teletext features side panels adding up to 16 additional columns on either side of the 40 column display.
Side panels are invisible to Level 1 decoders so they can only be used for decoration, not content. Here they extend the horizontal "scrollers" in this tribute to a shopping channel.
Side panels are invisible to Level 1 decoders so they can only be used for decoration, not content. Here they extend the horizontal "scrollers" in this tribute to a shopping channel.
October 16, 2024 at 2:18 PM
Level 2.5 #teletext features side panels adding up to 16 additional columns on either side of the 40 column display.
Side panels are invisible to Level 1 decoders so they can only be used for decoration, not content. Here they extend the horizontal "scrollers" in this tribute to a shopping channel.
Side panels are invisible to Level 1 decoders so they can only be used for decoration, not content. Here they extend the horizontal "scrollers" in this tribute to a shopping channel.
One week until #Teletext50 at Cambridge!
Here's a #teletext recreation of a poster I saw at the supermarket, an earlier version of which I somehow put onto every TV at Chunky Fringe 2021. A Level 2.5 rendering and two Level 1 renderings, with and without double size text.
Here's a #teletext recreation of a poster I saw at the supermarket, an earlier version of which I somehow put onto every TV at Chunky Fringe 2021. A Level 2.5 rendering and two Level 1 renderings, with and without double size text.
September 15, 2024 at 5:18 PM
One week until #Teletext50 at Cambridge!
Here's a #teletext recreation of a poster I saw at the supermarket, an earlier version of which I somehow put onto every TV at Chunky Fringe 2021. A Level 2.5 rendering and two Level 1 renderings, with and without double size text.
Here's a #teletext recreation of a poster I saw at the supermarket, an earlier version of which I somehow put onto every TV at Chunky Fringe 2021. A Level 2.5 rendering and two Level 1 renderings, with and without double size text.
The #WeeklyTeletextArt prompt this week is "Pop".
I already did PopMaster a few years back, so here's a #teletext recreation of the early 80s "Pop Quiz" titles. Circles, diagonals *and* dithering is such a devilish combination...
I already did PopMaster a few years back, so here's a #teletext recreation of the early 80s "Pop Quiz" titles. Circles, diagonals *and* dithering is such a devilish combination...
August 24, 2024 at 8:15 PM
The #WeeklyTeletextArt prompt this week is "Pop".
I already did PopMaster a few years back, so here's a #teletext recreation of the early 80s "Pop Quiz" titles. Circles, diagonals *and* dithering is such a devilish combination...
I already did PopMaster a few years back, so here's a #teletext recreation of the early 80s "Pop Quiz" titles. Circles, diagonals *and* dithering is such a devilish combination...
This weeks #WeeklyTeletextArt prompt is "Paris", but nobody said it had to be a #teletext recreation of a monument in the French capital.
Another excuse to recreate an album... I mean 7" single cover.
Another excuse to recreate an album... I mean 7" single cover.
August 13, 2024 at 4:48 PM
This weeks #WeeklyTeletextArt prompt is "Paris", but nobody said it had to be a #teletext recreation of a monument in the French capital.
Another excuse to recreate an album... I mean 7" single cover.
Another excuse to recreate an album... I mean 7" single cover.
Level 2.5 #teletext applies "enhancements" on top of a Level 1 page.
This glitch shows enhancements from the weather picture "enhancing" the wrong news page; colours from the rain and house are visible along with G3 mosaics over the last paragraph.
Shots from www.youtube.com/watch?v=I6uz...
This glitch shows enhancements from the weather picture "enhancing" the wrong news page; colours from the rain and house are visible along with G3 mosaics over the last paragraph.
Shots from www.youtube.com/watch?v=I6uz...
March 31, 2024 at 5:47 PM
Level 2.5 #teletext applies "enhancements" on top of a Level 1 page.
This glitch shows enhancements from the weather picture "enhancing" the wrong news page; colours from the rain and house are visible along with G3 mosaics over the last paragraph.
Shots from www.youtube.com/watch?v=I6uz...
This glitch shows enhancements from the weather picture "enhancing" the wrong news page; colours from the rain and house are visible along with G3 mosaics over the last paragraph.
Shots from www.youtube.com/watch?v=I6uz...
Another album cover recreated in #teletext this time it's the Steve Miller Band's "Italian X-Rays".
It's almost as if this one WAS done in teletext to begin with!
It's almost as if this one WAS done in teletext to begin with!
March 24, 2024 at 1:40 PM
Another album cover recreated in #teletext this time it's the Steve Miller Band's "Italian X-Rays".
It's almost as if this one WAS done in teletext to begin with!
It's almost as if this one WAS done in teletext to begin with!