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Raster CRT Typography According to DEC

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Re: Raster CRT Typography According to DEC

#31

Post by masswerk »

pushpop wrote: post #13
avian wrote: post #5

Interesting post. From my work on 1980s micros that used CRT TVs for display, the phosphor response described here seems to be a bit oversimplified. In my purely subjective experience, rise time seems to be shorter than fall time - pixels will usually be visibly blurred on the trailing (right) edge, but sharper on the leading (left) edge. Another thing I noticed is that a longer horizontal row of pixels will leave a…

TVs had their sub-pixels arranged differently to the CRTs on many computer displays. This lead to a lot of “fuzzing” beyond that phosphor response when computers were hooked up to TVs. A classic example of this is when you play retro consoles on an authentic household TV verses VGA. Some systems actually used this technique as an additional rendering trick. For example having a foreground sprite where every other pix…

(OP here). There are actually no pixels on a monochrome screen, rather, there's just an even phosphor coating. What we may assume to be a pixel is just an effect of the signal generating the pattern. Color TV changed this radically, as there was now a shadow mask and (usually) vertical strips of phosphor. However, pixels were still determined rather by the generating signal than by the subpixels of the shadow mask. (So a pixel may illuminate any number of phosphor regions exposed to the cathode ray at this very moment.) Moreover, a TV usually included some kind of sharpening circuitry, which was more tuned to moving images and didn't perform that well with static content. And, of course, various color systems (NTSC/PAL/SECAM) generated different effects and artefacts of their own.

Re: Raster CRT Typography According to DEC

#33

Post by pushpop »

masswerk wrote: post #31
pushpop wrote: post #13

Earlier quoted context omitted.

TVs had their sub-pixels arranged differently to the CRTs on many computer displays. This lead to a lot of “fuzzing” beyond that phosphor response when computers were hooked up to TVs. A classic example of this is when you play retro consoles on an authentic household TV verses VGA. Some systems actually used this technique as an additional rendering trick. For example having a foreground sprite where every other pix…

(OP here). There are actually no pixels on a monochrome screen, rather, there's just an even phosphor coating. What we may assume to be a pixel is just an effect of the signal generating the pattern. Color TV changed this radically, as there was now a shadow mask and (usually) vertical strips of phosphor. However, pixels were still determined rather by the generating signal than by the subpixels of the shadow mask. (…

Yes I know. My point was the arrangement of the RGB dots that made up a region was different on CRT TVs to that of colour CRT monitors (ignoring the old terminals for now because they’re a different era of device entirely). That did have an effect on the sharpness of the image.

What I didn’t mention but is also worth noting is the quality of the input signal would have mattered as well. 8bit micro monitors, even in the 80s, generally took RGB input. Whereas any micro that output to a TV would often do so via a the antenna, ie the computer would have to be tuned in like a TV station. This means you then have all of your prime colour “wires” as well as audio mixed into one analogue signal. Which obviously degrades the overall image and sound quality. Plus TV tuning isn’t nearly as precise as having a proper dedicated cable. The devices from the 80s (and 90s) which supported both ANT and RGB really show just how significant the difference between the two is. Which is also why you often see a lot of retro gear being sold as “RGB modded”.

Basically what I’m saying is comparing a budget micro on an 80s home TV to a raster CRT terminal is rather pointless. Different tech, different target audience, different eras.

Re: Raster CRT Typography According to DEC

#34

Post by pushpop »

abainbridge wrote: post #8
blattimwind wrote: post #7

Earlier quoted context omitted.

That's nothing! Tektronix did vector fonts in the 60s using analogue ROMs.

That's nothing, the Jaquet-Droz family were producing glyphs from mechanical analogue storage in ~1770. https://www.youtube.com/watch?v=bY_wfKVjuJM

That’s nothing, the Egyptians were writing glyphs to solid state analogue storage two thousand years before that. /s

Re: Raster CRT Typography According to DEC

#35

Post by masswerk »

pushpop wrote: post #33
masswerk wrote: post #31

Earlier quoted context omitted.

(OP here). There are actually no pixels on a monochrome screen, rather, there's just an even phosphor coating. What we may assume to be a pixel is just an effect of the signal generating the pattern. Color TV changed this radically, as there was now a shadow mask and (usually) vertical strips of phosphor. However, pixels were still determined rather by the generating signal than by the subpixels of the shadow mask. (…

Yes I know. My point was the arrangement of the RGB dots that made up a region was different on CRT TVs to that of colour CRT monitors (ignoring the old terminals for now because they’re a different era of device entirely). That did have an effect on the sharpness of the image. What I didn’t mention but is also worth noting is the quality of the input signal would have mattered as well. 8bit micro monitors, even in t…

My post wasn't meant as a critique, rather as an expansion on yours. We are so used to thinking in pixels that we often forget there weren't any hardware pixels in B&W. It was whatever the circuitry could produce. You observations on color TV are certainly right. From what I remember, the most obvious distortion came from the sharpening (which is seldom mentioned today), resulting in hard, double vertical edges. This may have been more prominent in PAL than NTSC. – How I did long for a legit RGB monitor, but it was just a color TV for my C64 anyway. :-)

Re: Raster CRT Typography According to DEC

#36

Post by theoh »

theoh wrote: post #27
ChuckMcM wrote: post #24

Earlier quoted context omitted.

I don't know either, however TI at the time also produced the "Silent 700" terminal series and it had the same font (all essentially upper case characters just some larger and some smaller. Perhaps it was an early example of the DRY mantra being applied incorrectly.

https://en.wikipedia.org/wiki/Small_caps

That was an unobjectionable comment, so I guess the downvotes are a stimulus to try to get me to write more. The Wikipedia page for the TI-99 mentions the "small capitals" but does not link to the page I linked to. So some people, at least, who read that page won't get the reference to the typographic tradition (if that's what it is).

A larger issue is the idea that, by choosing a small caps style for their font, TI were acting inexplicably or irrationally. It is worrying but not surprising that the HN crowd finds it disturbing when a company makes a creative decision that doesn't have a clear business case behind it, while being completely innocuous, and which potentially could have helped to differentiate their products. It's the typical negative engineer stereotype coming through: "No imagination or creativity allowed, except if it's to solve a specific problem".

Re: Raster CRT Typography According to DEC

#37

Post by masswerk »

abainbridge wrote: post #8
blattimwind wrote: post #7

Earlier quoted context omitted.

That's nothing! Tektronix did vector fonts in the 60s using analogue ROMs.

That's nothing, the Jaquet-Droz family were producing glyphs from mechanical analogue storage in ~1770. https://www.youtube.com/watch?v=bY_wfKVjuJM

Also, see the use of a metal plate as a binary storage device for fonts used for the print on punch cards with the IBM key punches:

https://www.masswerk.at/misc/card-punch-typography/

Re: Raster CRT Typography According to DEC

#38

Post by reaperducer »

It's interesting that DEC did horizontal pixel stretching because individual dots would be too precise to be seen because of phosphor latency.

The Commodore 64 had a similar problem with single-pixel latency, which is why the vertical portions of its character ROM are all two pixels wide. Otherwise, the character would be too blurry to be read comfortably on televisions of the era.

I used to love making my own C-64 fonts pixel by pixel and comparing how they looked on a Panasonic portable TV versus my Commodore CM-141 monitor.

Re: Raster CRT Typography According to DEC

#39

Post by reaperducer »

edejong wrote: post #2

Similar project is cool-retro-term [1] although I think the defaults are a little over the top. [1] https://github.com/Swordfish90/cool-retro-term

cool-retro-term is my go-to terminal program for quick projects that don't need multiple panes.

It freaks out the IT guys and our workspace consultants, which is a bonus.

The only downside is that on macOS it crashes on quit. But since I'm quitting it anyway, no harm done.

Re: Raster CRT Typography According to DEC

#40

Post by reaperducer »

int_19h wrote: post #23

On an unrelated note, I wish somebody made a modern portable and low-power hardware terminal. Something with eInk, or maybe even reflective LCD, like those old "electronic organizers", but with a full-size screen. If it can do serial and serial-over-USB, that can come in handy with headless boxes, RPi etc.

Until that happens, Prompt for iOS by Panic Software out of Portland is very useful. I've used it on my iPhone in emergencies for years, and recently put it on an iPad and it really shines.
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