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BASIC & Screenmodes

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  BASIC & Screenmodes Robert Heaton <rob@robheaton.co.uk> - 2012-07-18 21:04 +0100
    Re: BASIC & Screenmodes Matthew Phillips <spam2011m@yahoo.co.uk> - 2012-07-18 21:46 +0100
      Re: BASIC & Screenmodes Robert Heaton <rob@robheaton.co.uk> - 2012-07-19 06:28 +0100
        Re: BASIC & Screenmodes Martin <News03@avisoft.f9.co.uk> - 2012-07-19 10:18 +0100
          Re: BASIC & Screenmodes Robert Heaton <rob@robheaton.co.uk> - 2012-07-19 20:31 +0100
      Re: BASIC & Screenmodes druck <news@druck.org.uk> - 2012-07-19 21:52 +0100
        Re: BASIC & Screenmodes Robert Heaton <rob@robheaton.co.uk> - 2012-07-20 18:53 +0100
        Re: BASIC & Screenmodes jgharston <jgh@arcade.demon.co.uk> - 2012-07-20 14:07 -0700
          Re: BASIC & Screenmodes Justin Fletcher <gerph@gerph.org> - 2012-07-21 16:53 +0100
          Re: BASIC & Screenmodes druck <news@druck.org.uk> - 2012-07-21 19:21 +0100

#1934 — BASIC & Screenmodes

I'm working my way through the excellent book "Starting BASIC" by the 
late Ray Favre.

The main program that is built throughout the book runs in MODE 12, I'm 
using a Beagleboard running RISC OS 5.19 and whenever the BASIC program 
runs, I can't see the output.
My monitor just reports "out of range"

Is there an entry needed to the MDF file I'm using? Or can someone with 
more BASIC knowledge recommend a more suitable MODE?

Many Thanks,
Rob.

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#1935

In message <500716b9$0$7326$5b6aafb4@news.zen.co.uk>
 on 18 Jul 2012 Robert Heaton  wrote:

> I'm working my way through the excellent book "Starting BASIC" by the 
> late Ray Favre.
> 
> The main program that is built throughout the book runs in MODE 12, I'm 
> using a Beagleboard running RISC OS 5.19 and whenever the BASIC program 
> runs, I can't see the output.
> My monitor just reports "out of range"
> 
> Is there an entry needed to the MDF file I'm using? Or can someone with 
> more BASIC knowledge recommend a more suitable MODE?

MODE 12 was 640 x 256 pixels in 16 colours.

I guess it rather depends on the program you are trying to run whether it
matters much what the mode is.  It depends on whether it does tricks like
writing direct to screen memory.

If it doesn't, then your best bet (without creating an MDF, which might be
quite a challenge for such a low resolution) would be to go for a 16 colour
mode with a larger resolution.  Part of the screen would probably be unused,
but at least you would get output.

Except I suspect that the Beagleboard may not support 16 colour modes.  Or
maybe I am getting muddled up with the Iyonix which does not support 4 colour
modes.

You can alter the mode command to specify the resolution and colours.  To get
the string for you current mode, just go to the Display Manager tool on the
iconbar, click Menu and follow the "Mode" item.  For example, on this machine
(an Iyonix) I see

X1280 Y1024 C16M EX1 EY1

The EX1 and EY1 indicate the conversion of OS units to pixels: in this case 2
OS units per pixel in both dimensions.

In more recent versions of BASIC (RISC OS 3.5 onwards, I suspect) you can do

MODE "X1280 Y1024 C16M EX1 EY1"

There are a few other options.  Try

HELP MODE

to see them.

-- 
Matthew Phillips
Durham

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#1936

On 2012-07-18 20:46:34 +0000, Matthew Phillips said:

> In message <500716b9$0$7326$5b6aafb4@news.zen.co.uk>
>  on 18 Jul 2012 Robert Heaton  wrote:
> 
>> I'm working my way through the excellent book "Starting BASIC" by the
>> late Ray Favre.
>> 
>> The main program that is built throughout the book runs in MODE 12, I'm
>> using a Beagleboard running RISC OS 5.19 and whenever the BASIC program
>> runs, I can't see the output.
>> My monitor just reports "out of range"
>> 
>> Is there an entry needed to the MDF file I'm using? Or can someone with
>> more BASIC knowledge recommend a more suitable MODE?
> 
> MODE 12 was 640 x 256 pixels in 16 colours.
> 
> I guess it rather depends on the program you are trying to run whether it
> matters much what the mode is.  It depends on whether it does tricks like
> writing direct to screen memory.
> 
> If it doesn't, then your best bet (without creating an MDF, which might be
> quite a challenge for such a low resolution) would be to go for a 16 colour
> mode with a larger resolution.  Part of the screen would probably be unused,
> but at least you would get output.
> 
> Except I suspect that the Beagleboard may not support 16 colour modes.  Or
> maybe I am getting muddled up with the Iyonix which does not support 4 colour
> modes.
> 
> You can alter the mode command to specify the resolution and colours.  To get
> the string for you current mode, just go to the Display Manager tool on the
> iconbar, click Menu and follow the "Mode" item.  For example, on this machine
> (an Iyonix) I see
> 
> X1280 Y1024 C16M EX1 EY1
> 
> The EX1 and EY1 indicate the conversion of OS units to pixels: in this case 2
> OS units per pixel in both dimensions.
> 
> In more recent versions of BASIC (RISC OS 3.5 onwards, I suspect) you can do
> 
> MODE "X1280 Y1024 C16M EX1 EY1"
> 
> There are a few other options.  Try
> 
> HELP MODE
> 
> to see them.

Thank You!
I'll have a play and see how I get on.

Rob.

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#1937

> On 2012-07-18 20:46:34 +0000, Matthew Phillips said:

> > MODE "X1280 Y1024 C16M EX1 EY1"

If this is just to set the current mode, then a much easier way is to use

    MODE MODE

I know this looks odd, but the second MODE is used as a function, and
returns the current MODE. The first MODE then takes the returned value of
the second to set the MODE. The result is a full-screen, single tasking,
scrolling window rather like the old BBC days ... but in a rather higher
resolution.

But if the program depends on some aspect of the mode, then this may not
work.

-- 
Martin Avison 
Note that unfortunately this email address will become invalid
without notice if (when) any spam is received. 

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#1939

In message <52b1a701a5News03@avisoft.f9.co.uk>
          Martin <News03@avisoft.f9.co.uk> wrote:

>> On 2012-07-18 20:46:34 +0000, Matthew Phillips said:

>>> MODE "X1280 Y1024 C16M EX1 EY1"

> If this is just to set the current mode, then a much easier way is to use

>     MODE MODE

> I know this looks odd, but the second MODE is used as a function, and
> returns the current MODE. The first MODE then takes the returned value of
> the second to set the MODE. The result is a full-screen, single tasking,
> scrolling window rather like the old BBC days ... but in a rather higher
> resolution.

> But if the program depends on some aspect of the mode, then this may not
> work.


MODE MODE did the trick!
Thanks again.

Rob.

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#1940

On 18/07/2012 21:46, Matthew Phillips wrote:
> In message <500716b9$0$7326$5b6aafb4@news.zen.co.uk>
>   on 18 Jul 2012 Robert Heaton  wrote:
>> The main program that is built throughout the book runs in MODE 12, I'm
>> using a Beagleboard running RISC OS 5.19 and whenever the BASIC program
>> runs, I can't see the output.
>> My monitor just reports "out of range"
>>
>> Is there an entry needed to the MDF file I'm using? Or can someone with
>> more BASIC knowledge recommend a more suitable MODE?
>
> MODE 12 was 640 x 256 pixels in 16 colours.
>
> I guess it rather depends on the program you are trying to run whether it
> matters much what the mode is.  It depends on whether it does tricks like
> writing direct to screen memory.

Old programs will assume a 1280x1024 OS unit screen size for graphics, 
80x25 for text, and will probably depend on the 16 colour variable 
palette. All of which can be overcome, but not very straight forward for 
BASIC beginners.

> X1280 Y1024 C16M EX1 EY1
>
> The EX1 and EY1 indicate the conversion of OS units to pixels: in this case 2
> OS units per pixel in both dimensions.

X1280 Y1024 C16 EX2 EY3 would simulate the OS unit screen size, and give 
80x25 text, plus 16 colours. Graphics wouldn't look exactly the same as 
lines will be a lot thinner due to their being more pixels per OS unit. 
If 16 colours aren't supported use C256.

---druck

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#1941

On 2012-07-19 20:52:17 +0000, druck said:

> On 18/07/2012 21:46, Matthew Phillips wrote:
>> In message <500716b9$0$7326$5b6aafb4@news.zen.co.uk>
>> on 18 Jul 2012 Robert Heaton  wrote:
>>> The main program that is built throughout the book runs in MODE 12, I'm
>>> using a Beagleboard running RISC OS 5.19 and whenever the BASIC program
>>> runs, I can't see the output.
>>> My monitor just reports "out of range"
>>> 
>>> Is there an entry needed to the MDF file I'm using? Or can someone with
>>> more BASIC knowledge recommend a more suitable MODE?
>> 
>> MODE 12 was 640 x 256 pixels in 16 colours.
>> 
>> I guess it rather depends on the program you are trying to run whether it
>> matters much what the mode is.  It depends on whether it does tricks like
>> writing direct to screen memory.
> 
> Old programs will assume a 1280x1024 OS unit screen size for graphics, 
> 80x25 for text, and will probably depend on the 16 colour variable 
> palette. All of which can be overcome, but not very straight forward 
> for BASIC beginners.
> 
>> X1280 Y1024 C16M EX1 EY1
>> 
>> The EX1 and EY1 indicate the conversion of OS units to pixels: in this case 2
>> OS units per pixel in both dimensions.
> 
> X1280 Y1024 C16 EX2 EY3 would simulate the OS unit screen size, and 
> give 80x25 text, plus 16 colours. Graphics wouldn't look exactly the 
> same as lines will be a lot thinner due to their being more pixels per 
> OS unit. If 16 colours aren't supported use C256.

Thanks druck,
Your suggestion provides better results than the use of MODE MODE.

Rob.

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#1942

druck wrote:
> Old programs will assume a 1280x1024 OS unit screen size for graphics,
> 80x25 for text,

80x32 for text.

MODE 12:REPEAT:V%=VPOS:PRINT:UNTIL V%=VPOS:PRINT VPOS+1

JGH

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#1943

On Fri, 20 Jul 2012, jgharston wrote:

> druck wrote:
>> Old programs will assume a 1280x1024 OS unit screen size for graphics,
>> 80x25 for text,
>
> 80x32 for text.
>
> MODE 12:REPEAT:V%=VPOS:PRINT:UNTIL V%=VPOS:PRINT VPOS+1

<sob> That's not how you get the text height of a mode.
Depending on your intentions:

SYS "OS_ReadModeVariable", mode, 2 TO ,,lines_minus_one
   - maximum addressable line for any mode

data%!0=2:data%!4=-1
SYS "OS_ReadVduVariable", data%, data%
lines_minus_one = data%!0
   - maximum addressable line in the current mode

data%!0=257:data%!4=-1
SYS "OS_ReadVduVariable", data%, data%
lines = data%!0
   - lines in the current text window

It's also wrong to use OS_Byte 160 to obtain similar information, if you 
felt inclined to do that.

-- 
Gerph <http://gerph.org/>
... You're a fraud and you know it
     But it's too good to throw it all away

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#1944

On 20/07/2012 22:07, jgharston wrote:
> druck wrote:
>> Old programs will assume a 1280x1024 OS unit screen size for graphics,
>> 80x25 for text,
>
> 80x32 for text.

Sorry, you are correct.

---druck

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