MSX-BASIC 1 SCREEN IV

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By chalky

Resident (39)

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09-05-2009, 17:45

I have returned to MSX programming (BASIC to start with, while I plod my way through PROGRAMMING THE Z80) after a 22 year break and while researching on the internet found a wiki reference to an extension for MSX-BASIC 1.0/1.1 called "SCREEN IV" which apparently added a new screen mode via software only. Unfortunately I can't seem to find any other references to it anywhere. Can anyone tell me whether this really existed - and if so, whether it is available to download or buy?

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By Sonic_aka_T

Enlighted (4130)

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09-05-2009, 19:00

Well, it might have existed, but unfortunately you can't just automagically add a new screen mode by using software. Perhaps if you describe what the program supposedly did we can tell you how to reproduce the effect?

By Edwin

Paragon (1182)

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09-05-2009, 19:59

Maybe this refers to the trick by which you can use SC2/4 as tile mode in basic as well.

By chalky

Resident (39)

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10-05-2009, 01:19

Well, it might have existed, but unfortunately you can't just automagically add a new screen mode by using software. Perhaps if you describe what the program supposedly did we can tell you how to reproduce the effect?

The following wiki text prompted my post:

"Exploring the MSX BASIC extensibility it was possible to extend MSX BASIC solely via software. A very interesting extension to the MSX BASIC 1.0/1.1 was Screen IV, a tweak of MSX BASIC adding the mixed graphic/text mode Screen 4 (hence its name Screen IV), with 64 x 24 characters and Screen 2 resolution for graphics (256 x 192 pixels, 16 colors)."

I was hoping this "Screen IV" provided a screen mode similar to that used in "The Hobbit" (top 66%=hires graphics, bottom 33%=windowed text) and was available as a software extension.

By Edwin

Paragon (1182)

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10-05-2009, 02:45

Something like that could have been written. Although I am not so sure about the 64 characters, since that would only leave 4 px per letter. Which is possible (AGE does it), but not a very comfortable read.

By chalky

Resident (39)

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01-01-2011, 02:12

Apologies for bumping this old thread, but after 20 months of searching, I have finally tracked this SCREENIV expansion down.

It was originally published in the Portugese magazine CPU from issues 8 to 17. I would be amazed if anyone actually got it to work, since it was full of printing errors in both the Hex listings and in some of the instructions regarding hook changes etc. (there were also 2 massive blocks of hex with memory addresses that were located several hundred bytes from where they should have been).

Having found a copy of MSXDEBUG, I have now successfully compiled SCREEN4.COM, and have a "new" MSX1 screen mode which allows full graphics combined with 64 characters per line text. It also adds some new commands (for use in Screen 4) such as "PRINT @", "OVER" and "SCREEN OUT". There is no denying that the text is a little hard on the eyes, but the speed is pretty amazing nevertheless.

If anyone wants a copy and can tell me how to share this on here I will gladly do so.

By sd_snatcher

Prophet (3092)

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01-01-2011, 03:29

As it's a freeware, it could be published on MRC's download session.

By Leo

Paragon (1236)

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01-01-2011, 10:00

Hi , many thanks for sharing , very interesting screen mode !!!

my email is in my profile : can you send it to me ? please ?
!)

By chalky

Resident (39)

chalky's picture

01-01-2011, 11:37

@Leo: I tried sending it to the email address in your profile - but get delivery failure notifications every time...

@sd_snatcher: that would be ideal as it makes it available for anyone who wants it, but I tried submitting a PC utility to view MSX Basic files several months ago and never got a response. Is downloads@msx.org the only route I can use (unfortunately I have no hosting facilities)?

By Leo

Paragon (1236)

Leo's picture

01-01-2011, 11:49

too bad , but someone yesterday sent me a email from this forum so it might be your address that is bounced by my gmail ...
This piece of sw resurected is very interesting ... maybe you can try leopomme@yahoo.fr if you have time ....
good job again
:)

By chalky

Resident (39)

chalky's picture

01-01-2011, 11:57

@Leo: Just tried your 2nd address - no error message, so hopefully you have mail! Smile

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