No, I don't expect a 805x to be used with MPEG video. But I don't expect a 805x to be used for a rastered laser display either. But video is a significant reason for switching from vector to raster output. Why else switch to a solution that gives 0.01 or 0.001 times the intensity?

And if I would use a microcontroller with any kind of raster display of non-trivial resolution, I would prefer something else than a 805x chip. I would like something that can play with an image buffer without extra clock cycles to fight with a dedicated index pointer. Would you be able to use a 805x processor to produce a 256x256 bitmap at 50 fps for the laser show I linked to earlier? A 805x could control a XY projector while mostly idling. How many pixels/second can you get the 805x processor to draw for diagonal lines?

No, a laser does not produce a pixel. It does produce a ray. It isn't until you sweep the ray while modulating the beam that you get pixels, as the term pixel is normally used. The thing here is that pixel (picture element) isn't really defined other than for raster displays.

With semiconductor lasers, you can modulate the beam by modulating the supply current. If you need to compensate for the intensity loss of switching from a vector display to a raster display (given the fact that if you display vector data on a raster display, most pixels will be off), you can't use a semiconductor laser. But then you would need optical modulation. How do you optically modulate a laser at these speeds? High-intensity XY projectors can use a mirror or similar to cut off the ray. But emitting pixels instead of vectors requires orders of magnitude faster modulation.


No problem with that. Lots of proof that 8-bit processors (805x, AVR, Z80, PIC, ...) works fine.


For displaying static images, it would be way easier with a motor-driven dia projector. Way higher resolution. Way higher intensity. Way simpler. To sell in a raster-based laser projector, you should describe what advantages it would have. And given the cost of lasers to get any reasonable intensity, you could buy the cheapest LCD projector and then pay for a number of lamps, without reaching the cost of the lasers. That would give you at least VGA-class graphics with an interface a normal PC can use. But it would not manage to match the capabilities of a XY-driven laser projector. Try drawing in the air. Try drawing infinite-resolution curves generated in real-time from music. That is something unique with a XY-controlled laser projector - something that motivates bilding a laser projector in the first place. Nothing beats a XY-controlled laser projector for dynamic vector output. "Everything" beats a raster-driven laser projector for just about everything.


If you learned your lesson, then you should know the difference between XY and raster. You would not have managed the resolution or intensity if you had selected a raster solution. Why arguing so much about killing off the advantage of the laser by forcing it into a niche where it will be totally beaten by other - cheaper - technologies? This discussion may end up differently 10 years from now, but right now, you are having a very tough time convincing anybody about the advantages of using a laser for a raster display.


You have a large number of times in this thread talked about how easy it is to control a rotating mirror. Where have you any single time compared the ease of the rotating mirror with the other implications? Not once have you responded about intensity. Not once have you talked about how to modulate the beam. Not once have you discussed how to power or cool the laser. Not once have you talked about how capable a 805x processor is of creating frame buffers for controlling a raster display. Since you are ignoring all comments about problems, I must ask: Are you intentionally trying to fool people into thinking that raster output is a good solution given the current state of technology?

This is similar to the matrix-LED thread where you spent a large number of posts talking about driving the individual diodes one at a time with us timing, even if a LED display drives all diodes of a full scanlines or the full display concurrently.


If Chico would settle for 256 x 192 with a laser of 0.5W optical output, he would project 10uW of light / pixel, given 100% efficient modulation and mirrors. How large can he display without requiring the room to be blackened? If we assume that a LED has 10% efficiency, then a raster display driven with a laser of 0.5W optical output would be similar to a LED display where each LED is driven by 2V and 0.05mA. Sounds selling? Remember now, that if a LED has 10% efficiency, then the 0.5W optical output laser should be compared with a LED panel fed by a maximum of 5W with all 49152 LEDs lit. 5W electrical power for 50k diodes...

If you switch from pixels to a XY display, you would notice that 5 1W Luxeon star would produce a lot of light. For a typical graph a 805x can emit (yes, no video) you would probably have a 100:1 to 1000:1 quota between lit and non-lit pixels. Do you think Chico would think such a difference in intensity important? Or would he think it irrelevant, just because a rotating mirror is so sexy? After all, the web have seen hundreds of people managing to build XY projectors. How many have you seen where someone have built a raster display? Shouldn't most projects have been using rotating mirrors if a raster display is so much easier?

Let's continue with the 256 x 192 example. A raster display runs at a fixed frame rate. Let's settle for 30 fps. That gives a pixel frequency of 1.5MHz. How easy would it be for your 805x to render 30 bitmaps/second? It should clear the memory and then draw an unknown number of pixels. You did intended Chico to emit moving data, didn't you? Or just settle for an expensive dia projector without the intensity?

When talking about normal LEDs in a previous thread, you were very concerned about the ability of a LED to be turned on/off with us timing. No worry about doing the same for a powerful laser diode (way more powerful than used in fiber communications)? And what if Chico thinks 0.5W is too little optical power and wants a HeNe laser? It can't be electrically modulated, so how do he optically modulate it at these frequencies? Irrelevant, since the rotating mirror is so simple that all other design issues can be ignored?

What more - a diagonal line on a 256 x 192 pixel raster display will be very jaggy. This is less than the resolution of the old CGA graphics we hated so much. A vector projector would have an infinite resolution for the beam to move between p0 and p1. It would only be the corner points p0 and p1 that would be limited by the resolution of the DAC and the mechanical resolution of the galvo.

And a single dot will be a single dot, not a short horisontal line - remember that the laser beam is thin. You don't focus it like you focus the electron beam of a CRT. If the ray is 1mm and the display is 256x192 mm or smaller, the individual traces will touch each other. What do you do if you want a larger display? A positive and a negative lens to increase the laser beam to 5mm? Sounds simpler than it is. Especially if you want to use multiple lasers to get RGB or RGY.


The rasterised display runs no risk of overheating the laser? Because it will normally only make use of 1% or less of the light output of the laser? Sounds like a good tradeoff... And if switching to a gas laser, the laser would have to be lit all the time - you just have to figure out how to modulate the light beam. And to cool away the excess heat for the 99% of the time when the laser is wasting the output somewhere else.


No, I have never said that there are any real problems creating a bitmap with fills. What I have said, is that a laser beam is not good at area filling at the powers currently available. With XY output, you can get very strong intensity. Trying to fill an area will either require a XY projector to lose frame rate, or a raster display to move the ray at so high speed that the surface intensity will be very low. It doesn't matter what technology you use for aiming the laser - you need stronger output to fill an area with significant intensity. It is still way easier and cheaper to produce strong electron beams than it is to produce strong laser beams.


A common average seek time for a typical disk head is way better than 10ms. Just hitting the track (read mode - about 1/10000 of the full stroke) or getting perfectly aligned on the track (write) can represent 1ms. And the servo information comes from the rotating surface. But I'm not convinced that a disk assembly is a good choice for controlling a XY projector. Loudspeaker solutions should probably be faster, and home-built galvos can be very fast.


Your one advantage with a raster display. Repeated many times in this thread, but without any comment about the disadvantages involved. Without commenting on all other aspects, you can't sell in a raster display as a good choice.


With what intensity? How large projection? How powerful laser? Rendered by a 805x? In real-time? What percentage of the pixels were lit?

For displaying 2D raster output, I would think it is way easier to find a way to replace the lamps in traditional LCD or DLP projectors with high-intesity LEDs (and also way safer) than it would be to manage to design general raster projectors with lasers. The strengths of a laser projector lies in the extreme intensity it can produce for vector output, and its ability to draw in the air.

The feature that is interesting with a raster-capable laser projector is the work with the generation of true 3D images, where you are projecting the image in a volume instead of on a plane, so you don't just get one image for each eye but can move around and view an object from other angles. But that is outside the simple rotating mirror concept.