jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 23710
Joined: Sat Jul 30, 2011 7:41 pm

Re: composite resolution too low to be of use for programming?

Mon Jan 23, 2012 10:55 pm

Joules said:


Keep it in perspective, the composite output isn't for rooting tooting high end graphics.  It allows you to program in a text environment.  For simple programs and graphics it's fine.

Remember, the whole point of this project and try to put yourself in the shoes of someone in a position of ONLY having a TV to use as a VDU.

Sometimes I scratch my head at the expectations that people have for the Raspi.  It's not a CRAY.


Although it is more powerful that a Cray-1. But doesn't look as cool.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed. Here's an example...
"My grief counseller just died, luckily, he was so good, I didn't care."

Joules
Posts: 87
Joined: Sun Dec 25, 2011 8:50 pm

Re: composite resolution too low to be of use for programming?

Tue Jan 24, 2012 1:37 am

Bring on the comfy seats…. For those not old enough to remember the Cray-1, take a look at this and revel in what the Raspberry Pi has to offer, for less that 8.86M$

http://www.openloop.com/educat.....ithAdd.htm

mixedfruit
Posts: 16
Joined: Sat Dec 17, 2011 6:35 pm

Re: composite resolution too low to be of use for programming?

Tue Jan 24, 2012 2:15 am

super_tnt said:


The screen I plan on using also connects via rca but it gives out a resolution on the description so this means I can use the pi at that resolution, right?


i think its a case of if you want to use linux in shell mode then you 'should' be ok, but if you want to use it with a gui (like x) then its most probably a no-go. But it depends if you just need to view things like video or if you want to read text (and how much on screen at once, font size etc)... and its all a bit of guess work really at the moment until we can get our hands on the real r-pi's..... i now have a little 14" sony portable crt tv ready and waiting for a rp-i test...

kme
Posts: 448
Joined: Sun Sep 04, 2011 9:37 am

Re: composite resolution too low to be of use for programming?

Tue Jan 24, 2012 2:27 am

Joules said:


Bring on the comfy seats…. For those not old enough to remember the Cray-1, take a look at this and revel in what the Raspberry Pi has to offer, for less that 8.86M$

http://www.openloop.com/educat.....ithAdd.htm


Oh, that was a good read. Max 8 MB RAM and consuming 115 kW! In my country normal households only have access to 6 kW I once actually touched a Cray-1 in Finland. It was a wreck only on display, but still.

In also makes you wonder if computer hardware design is in as sad state as software is. Todays supercomputers are utterly boring as all they do is to increase the number of stock x86 CPUs from xxx to 2 times xxx.

Where are todays Cray-1 or todays DEC Alpha?

super_tnt
Posts: 32
Joined: Mon Jan 16, 2012 2:13 pm

Re: composite resolution too low to be of use for programming?

Tue Jan 24, 2012 10:17 am

If the resolution is 800x600 I am more than fine in using it as I've seen it on a virtual box. It is small, yes but I find it just right. If it's lower than that then yeah I want be able to use it.

geeday
Posts: 23
Joined: Mon Jan 23, 2012 10:13 pm

Re: composite resolution too low to be of use for programming?

Wed Jan 25, 2012 10:29 pm

roelfrenkema said:


What a load of crap really, you want higher resolutions? Just ssh into console and you can have any resolution you want.



I can just see these 3rd world kids using their spare computer with huge flat screen monitors to SSH in to their Raspberry for awesome resolution

libreuniverse
Posts: 15
Joined: Mon Jan 23, 2012 7:30 am

Re: composite resolution too low to be of use for programming?

Thu Jan 26, 2012 6:46 am

It's safe to say that getting the vt's, or worse, framebuffer-enabled vt's to work on those screens is going to be a challenge. But probably not more than installation is. I've used tv's for text programming before, it works best in a huge font in an X term, and you're really better off with more like 40x24 than 80x24.

Hopefully it improves as LCD televisions take over the world.

User avatar
DavidS
Posts: 4334
Joined: Thu Dec 15, 2011 6:39 am
Location: USA
Contact: Website

Re: composite resolution too low to be of use for programming?

Fri Jan 27, 2012 6:57 pm

super_tnt said:


If the resolution is 800x600 I am more than fine in using it as I've seen it on a virtual box. It is small, yes but I find it just right. If it's lower than that then yeah I want be able to use it.



You can not do 800x600 over composite.  See my above post for an idea of what composite is capable, it has to do with the signal encoding not what the TV is capable of.
RPi = The best ARM based RISC OS computer around
More than 95% of posts made from RISC OS on RPi 1B/1B+ computers. Most of the rest from RISC OS on RPi 2B/3B/3B+ computers

tufty
Posts: 1456
Joined: Sun Sep 11, 2011 2:32 pm

Re: composite resolution too low to be of use for programming?

Fri Jan 27, 2012 8:05 pm

Thinking back, my Atari ST did 640x200 comfortably, and (albeit rather flickery and pretty much unusable) 640x400 using a tsr that made it think it had a "high resolution" monitor attached. Given that its palette and charset were far from optimised for tv usage, i"d suggest 640x480 could be quite usable. Have to forget about "modern" space hogging guis, though.

Actually, NeXTStep/OpenStep was usable at 640x480, too. GnuStep/WindowMaker might be a decent environment. Otherwise I"d probably sugest sawfish and enlightenment with a compact theme.

Simon

Bakul Shah
Posts: 320
Joined: Sun Sep 25, 2011 1:25 am

Re: composite resolution too low to be of use for programming?

Fri Jan 27, 2012 10:49 pm

JamesH said:


Joules said:


Sometimes I scratch my head at the expectations that people have for the Raspi.  It's not a CRAY.


Although it is more powerful that a Cray-1. But doesn't look as cool.


Raspi has a higher clock rate but in many other respects it is still behind! Here, look for yourself in the CRAY-1 Hardware Reference Manual!

kme said:


Where are todays Cray-1 or todays DEC Alpha?


This may be of interest to people: Homebrew Cray-1A

super_tnt
Posts: 32
Joined: Mon Jan 16, 2012 2:13 pm

Re: composite resolution too low to be of use for programming?

Sat Jan 28, 2012 12:46 am

DavidS said:


super_tnt said:


If the resolution is 800x600 I am more than fine in using it as I've seen it on a virtual box. It is small, yes but I find it just right. If it's lower than that then yeah I want be able to use it.


You can not do 800x600 over composite.  See my above post for an idea of what composite is capable, it has to do with the signal encoding not what the TV is capable of.


Oh OK that's really worrying, I guess I'll have to scrap my project then, so the is no way of doing this then?

willrandship
Posts: 51
Joined: Tue Sep 13, 2011 5:08 pm

Re: composite resolution too low to be of use for programming?

Sat Jan 28, 2012 1:01 am

Yeesh, 640x480 isn't that bad, you just can't use very serif-y fonts, and they have to be fairly large. Try setting a default font terminal to 69x26 chars to see 640 by 480. really quite readable. (I'm using a size 12 monospace font)

Keep in mind, though, that I regularly program on a 96x64 calculator screen 4x6 fonts FTW

Here's a few screenies of BBC Basic on said calculator: Link

Joules
Posts: 87
Joined: Sun Dec 25, 2011 8:50 pm

Re: composite resolution too low to be of use for programming?

Sat Jan 28, 2012 1:25 am

I think you will find the Cray maxed out at 160MIPS, given that it"s 64bit rather than 32bit of the Raspi and it hits 900MIPS. Not to mention reduced latency in the board and memory, the Cray is just outclassed even by the Raspi"s "modest" spec.

But thanks for that great document, if you have any more gems like that I would be grateful for any links.

willrandship
Posts: 51
Joined: Tue Sep 13, 2011 5:08 pm

Re: composite resolution too low to be of use for programming?

Sat Jan 28, 2012 1:36 am

Also,, at the original post, it sounds like you were using the Vbox guest additions features to resize it? Why not try it with the actual display resizing tools? I've used debian at 640x480 before myself, and it runs fine, although everything is a tad large and pixely.

Bakul Shah
Posts: 320
Joined: Sun Sep 25, 2011 1:25 am

Re: composite resolution too low to be of use for programming?

Sat Jan 28, 2012 9:49 am

Joules said:


I think you will find the Cray maxed out at 160MIPS, given that it"s 64bit rather than 32bit of the Raspi and it hits 900MIPS. Not to mention reduced latency in the board and memory, the Cray is just outclassed even by the Raspi"s "modest" spec.

But thanks for that great document, if you have any more gems like that I would be grateful for any links.



The Raspi's integer op/sec may be close but when it comes to flops (double prec. floating pt ops/sec), it doesn't even come close (Cray-1A peak vector perf is 160Mflops -- with 8 banks of 64 registers (64bit wide) you didn't have to go to its main memory all the time). Of course, it weighed a few tons and burned 115 kWatts and you had to use the whole machine as a GPU as was done for the movie TRON!

More docs at http://bitsavers.org/pdf/cray -- includes an assembler reference manual. A cray-1 simulator would be a great project on the Raspi!

super_tnt
Posts: 32
Joined: Mon Jan 16, 2012 2:13 pm

Re: composite resolution too low to be of use for programming?

Sat Jan 28, 2012 10:30 am

Just tried a debian vm at 640x480 and its fine, so I guess my project is back on, don't know why I was so hasty but at least I don't have to scrap my project

andyl
Posts: 265
Joined: Tue Jan 10, 2012 11:05 am

Re: composite resolution too low to be of use for programming?

Sat Jan 28, 2012 11:45 am

Bakul said:

(Cray-1A peak vector perf is 160Mflops -- with 8 banks of 64 registers (64bit wide) you didn't have to go to its main memory all the time). Of course, it weighed a few tons and burned 115 kWatts and you had to use the whole machine as a GPU as was done for the movie TRON!
A number of machines were used for TRON.  I know they also used the Foonly F1 for some of their rendering.  The Foonly was a kind of in the PDP-10 family and was a 36 bit machine.  It was also used for rendering Flight Of The Navigator.  A single 6000x4000 frame of that took 20 minutes to render.

ta2025
Posts: 19
Joined: Wed Jan 25, 2012 6:29 pm

Re: composite resolution too low to be of use for programming?

Thu Feb 16, 2012 7:58 pm

Chromatix said:


I think that would be done using the consolefont system, which is probably handled by a different init script in each distro.  The appropriate incantation should be derivable from there.

BTW, I would probably recommend nano to Linux newbies rather than vi or emacs.  Being much simpler, it's much harder to get lost in - and it even has on-screen help which explains how to exit (etc).  All good features gained from a user-centric rather than hacker-centric design.


Or Joe.  Joe has great syntax highlighting and uses the Wordstar/TurboC editor Keystrokes.

User avatar
SN
Posts: 1014
Joined: Mon Feb 13, 2012 8:06 pm
Location: Romiley, UK
Contact: Website

Re: composite resolution too low to be of use for programming?

Fri Feb 17, 2012 11:21 pm

At 46 years old i am a fully paid up member of the 1980"s pre-pc home computer club having worked my way through such beauties as the ZX81, ZX-Spectrum, Commodore 64, Amstrad CPC6128 and Atari STFM. And I can confirm that an 80 column display on a TV is hard work. Lately I have my Wii hacked and I can get an 80 column text display running a Linux Shell and it doesn"t really work either even on my 42" Plasma TV. . .
Steve N – binatone mk4->intellivision->zx81->spectrum->cbm64->cpc6128->520stfm->pc->raspi ?

Docteh
Posts: 32
Joined: Tue Jan 31, 2012 6:20 am

Re: composite resolution too low to be of use for programming?

Mon Feb 20, 2012 7:13 pm

Nothing looks better to me than a 80x24 console being rendered at 1080p

carveone
Posts: 2
Joined: Wed Feb 22, 2012 4:08 pm

Re: composite resolution too low to be of use for programming?

Wed Feb 22, 2012 4:43 pm

super_tnt said:


Just tried a debian vm at 640x480 and its fine, so I guess my project is back on, don't know why I was so hasty but at least I don't have to scrap my project


I don't know how the composite is implemented by the processor - the config.txt thread shows a few settings: specifically sdtv_mode and sdtv_aspect. It looks like you can use framebuffer_width and height too but to what effect I'm not sure. I guess we'll wait and see.

The point is that by dropping the chroma you might increase the possible resolution - the problem with composite is primarily the low bandwidth assigned to the chroma causing it to smear into a big mess at higher resolutions. FYI there's some information and some really good pictures at this wikipedia article:

http://en.wikipedia.org/wiki/D....._standards

You could get much better quality if you separate the signals out into component but that's not implemented here. I had the same idea before as one of the guys earlier in the thread (nice one!) - use teletext to implement stable colour text using composite - but, er, that might be impossible on this board

Nonetheless, I like it! Press teletext for help!

Still heading through the config.txt thread, dom says the PAL resolution is 720 x 576. That's "Pal DVD" resolution. I'm not sure what games are played in the processor to make that work. (Because you can't just do that resolution like a computer display and not expect it to look pants). Video would be ok though.

drgeoff
Posts: 9825
Joined: Wed Jan 25, 2012 6:39 pm

Re: composite resolution too low to be of use for programming?

Thu Feb 23, 2012 6:14 pm

DavidS said:


.. or interleave the color between frames to get a good sharp image.


Polite reply:  technical mumbo-jumbo

Less polite version:  rubbish.

drgeoff
Posts: 9825
Joined: Wed Jan 25, 2012 6:39 pm

Re: composite resolution too low to be of use for programming?

Thu Feb 23, 2012 6:31 pm

DavidS said:


And yes for a full vertical resolution you do need interlacing, this does cause some flickering.   The flicker can be reduced enough to be comfortable by putting a simple $5.00USD polarizing filter (vertical orientation) in front of the display.


Sorry, more mumbo-jumbo.  The only way an optical filter (whether polarising or something else) can reduce interlace flicker is to reduce the brightness of the displayed info.  Just as easily and more cheaply done with the control on the monitor.

Only a long phosphor CRT or an LCD display will give high brightness, flicker free display of interlaced video which fully exploits the interlace to give extra vertical resolution.

drgeoff
Posts: 9825
Joined: Wed Jan 25, 2012 6:39 pm

Re: composite resolution too low to be of use for programming?

Thu Feb 23, 2012 6:36 pm

carveone said:

I had the same idea before as one of the guys earlier in the thread (nice one!) - use teletext to implement stable colour text using composite - but, er, that might be impossible on this board
Nonetheless, I like it! Press teletext for help!


Indeed not possible with the RP.

User avatar
jojopi
Posts: 3085
Joined: Tue Oct 11, 2011 8:38 pm

Re: composite resolution too low to be of use for programming?

Thu Feb 23, 2012 8:29 pm

drgeoff said:

Indeed not possible with the RP.
Do you mean to say that the Pi's overscan does not extend into any of the lines where any TV will recognize a teletext clock run-in, or that the available dot clocks on the Pi are neither high enough nor sufficiently close to a multiple of the teletext bit rate to allow the generation of a decodable waveform?

Return to “Staffroom, classroom and projects”