ProDigit
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Re: Historical high resolution graphics on the Raspberry Pi

Mon Jul 29, 2019 7:22 am

As far as I understand, Vector displays, crt or LCD shouldn't matter.
They're all driven by a GPU processor, in worst case pushing signal through a 2 lead coax or video signal cable. In better ways, to a multi lead HDMI cable.
The vectors are generated by the hardware. The display and transfer medium (HDMI or coax), are only the last bit of the chain.
Modern hardware can easily display on a 4k screen through HDMI, what a CRT could display through a coax.
Modern LCD screen, kind of work the same as a CRT, in that they refresh each of the 720, 1080, 1440, or 2160 pixel lines, multiple times a second, on a line by line, and pixel by pixel basis.


If a 4Mhz CPU can display 5 moving vectors on a 320x240 (0.75Mpix) screen at 24Hz, in theory a 1,6 Ghz CPU being over 400.000x faster, should be able to fill a 4Mpix (4k) screen with 160.000 of them, or one vector each 5 by 5 pixels in size (any larger vectors, and they'd have to start overlapping, because every square pixel of the screen would be utilized).
It's another story entirely in practice, but I'm fairly certain that with some video optimization, even the pi, can push some serious amount of vectors on the screen...

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scruss
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Re: Historical high resolution graphics on the Raspberry Pi

Mon Jul 29, 2019 8:09 am

ProDigit wrote:
Mon Jul 29, 2019 7:22 am
As far as I understand, Vector displays, crt or LCD shouldn't matter.
Except that nobody makes a vector LCD display.
If a 4Mhz CPU can display 5 moving vectors on a 320x240 (0.75Mpix) screen at 24Hz, in theory a 1,6 Ghz CPU being over 400.000x faster, should …
No, you misunderstand: vector displays don't have pixels. Raster computer displays no longer have an electron beam scanning inside a CRT. Every pixel of the display is refreshed at a fixed frequency, even if it's not illuminated.

On a vector display, though, the beam doesn't even touch the parts of the display if they're not lit. In its simplest form, a vector display uses three analogue signals — X, Y and brightness — to draw the screen. Once it's drawn all the items in the display list, it goes back and refreshes them, possibly in their new position if they've moved. If you magnify a line on a vector display, there are no pixels or steps: only glowing phosphor. Vector displays do filled areas very badly, where it's no extra effort on a raster display.

The Atari vector machines might've had 320 x 240 addressable points, but that only means they had a minimum DAC width of 9 bits horizontally and 8 bits vertically. We can simulate them today with very fine dot-pitch LCDs, but we're pumping millions of times more information to the screen to do so. It's a hardware problem: vector-scan LCDs are not manufactured.

The wikipedia Vectrex article has a good description of how a simple vector display worked. The old Tek displays produced useful output at 1024 by 780 addressable points when fed at 2400 baud; by contrast, the most you could do with a raster display at that speed is 10 × 10 pixels at 24 Hz, monochrome — a measly 0.0001 Mpix!
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ProDigit
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Re: Historical high resolution graphics on the Raspberry Pi

Tue Jul 30, 2019 12:22 am

Interesting!
However, if vector displays don't have good fill rate, can't modern hardware like the Pi, drive a vector display to 'fill with vectors'?
I mean, if a GPU is 1000x faster than a video chip of 1980, wouldn't it make sense there's access to 1000x more vectors?

drgeoff
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Re: Historical high resolution graphics on the Raspberry Pi

Tue Jul 30, 2019 7:32 am

ProDigit wrote:
Tue Jul 30, 2019 12:22 am
Interesting!
However, if vector displays don't have good fill rate, can't modern hardware like the Pi, drive a vector display to 'fill with vectors'?
I mean, if a GPU is 1000x faster than a video chip of 1980, wouldn't it make sense there's access to 1000x more vectors?
You still don't understand vector displays. Until you do, their limitations and the impossibility of overcoming them with faster processing will be lost on you.

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rpdom
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Re: Historical high resolution graphics on the Raspberry Pi

Tue Jul 30, 2019 7:37 am

drgeoff wrote:
Tue Jul 30, 2019 7:32 am
ProDigit wrote:
Tue Jul 30, 2019 12:22 am
Interesting!
However, if vector displays don't have good fill rate, can't modern hardware like the Pi, drive a vector display to 'fill with vectors'?
I mean, if a GPU is 1000x faster than a video chip of 1980, wouldn't it make sense there's access to 1000x more vectors?
You still don't understand vector displays. Until you do, their limitations and the impossibility of overcoming them with faster processing will be lost on you.
Perhaps an anology?

Standard (raster) displays work like a laser printer that generates a page from lines of dots.

Vector displays are like a plotter that draws images by moving a pen around the paper in all directions.

jamesh
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Re: Historical high resolution graphics on the Raspberry Pi

Tue Jul 30, 2019 10:36 am

Principal Software Engineer at Raspberry Pi (Trading) Ltd.
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scruss
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Re: Historical high resolution graphics on the Raspberry Pi

Tue Jul 30, 2019 11:43 am

rpdom wrote:
Tue Jul 30, 2019 7:37 am
Vector displays are like a plotter that draws images by moving a pen around the paper in all directions.
Did someone say plotter?

https://www.youtube.com/watch?v=635_2U10kio

Six minutes of why you never let a vector device do flood fills.The pen change at 3:30 is quite neat, though.
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ProDigit
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Re: Historical high resolution graphics on the Raspberry Pi

Tue Jul 30, 2019 8:38 pm

Ok, so the vector limitation is in the screen.

drgeoff
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Re: Historical high resolution graphics on the Raspberry Pi

Tue Jul 30, 2019 10:54 pm

ProDigit wrote:
Tue Jul 30, 2019 8:38 pm
Ok, so the vector limitation is in the screen.
https://www.youtube.com/watch?v=JDSPwexlyTo

rricharz
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Re: Historical high resolution graphics on the Raspberry Pi

Fri Aug 09, 2019 7:01 am

I have added some plot files of the spacelab made with the tek4010 emulator and the ICEMDDN CAD package made on a CDC Cyber 175 mainframe emulator in my github repo. Thanks to Nick Glazzard for the plot files. These could definitely benefit from a screen with 4K resolution.

Image

dgoadby
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Re: Historical high resolution graphics on the Raspberry Pi

Sat Aug 17, 2019 5:30 pm

This is really impressive and it even looks right. I worked on the 4010's when I was with IBM. Rolls Royce Derby (before they went bust the first time) used them to model components for the the RB211 engine.

IIRC these units were actually storage scopes with a vector generator to draw the lines on the screen. There was no digital storage as we have now; it was just the screen. The screen used the photoemission effect to "drive" electrons out of the phosphorus and maintain the initial glow. Tektronix had storage oscilloscopes that used the same process. The screen could only be erased and redrawn. Real memory was very expensive back then so this design made the 4010 king of the hill in terms of resolution. The visible resolution was 1024 x 768 although the protocol permitted 1024 x 1024. The 4:3 screen chopped off 256 lines. The interfaces were usually a RS232 or current-loop teletype interface. They were heavy too at around 80 pounds and cost around $4500. Cheaper memory slowly killed them off.

Quirky fact: to draw a dot you actually draw a 0 length line from x,y to x,y.

I liked your project so much that I will run a copy on a RPI4 that has just arrived. ;-)

You have excelled yourself and awakened some good memories of my IBM mainframe days. Loved it!

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scruss
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Re: Historical high resolution graphics on the Raspberry Pi

Thu Nov 21, 2019 1:46 pm

If you want to generate your own Tek displays, Soruk has just updated stardot/MatrixBrandy: Fork of Brandy BASIC V for Linux to include Tek terminal support. If run in an xterm or under tek4010, any PLOT output from BASIC is output in Tek graphics commands.

Here's the link on stardot for more details: Re: Matrix Brandy BASIC VI for Linux with SDL: V1.22.1 released
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