Re: Foutje, bedankt!

From: Andre Fachat (a.fachat_at_physik.tu-chemnitz.de)
Date: 1998-03-29 15:53:02

rbaltiss@worldaccess.nl wrote:
> About screen blanking: my 8032SK has NO graphics on its keyboard which means it 
> isn't able to produce them. But it does :-(. Anyway, the SCHs Chris Sent me 
> says you can use a 6316 as well as a 6332 as ROM. Using a 6316 means that the 
> GRAPHICS line is attached  to a ChipSelect instead of a addressline. In this 
> case it means that applying a (L) to GRAPHICS the ROM is disabled, meaning 
> outputting nothing (but read as $FF) meaning black screen!.

Hm. Not having the symbol on the keyboard doesn't mean not being able
to produce them. After all by switching the _charrom_ to graphics mode
the upper case chars become lower case chars and the upper case chars
become graphics characters. There is, however a set of graphics chars
you don't get with the keys - in the C64 you can use the C= key for most
of them. My 8296 doesn't have graphics chars on the keyboard, but still
produces them.

Hm. 128 chars times 8 bytes per char makes 1k charrom (the 8th bit is 
inverting the character by hardware) for one character set. 
1k fits into a 6308.
2k make up the upper/lower and upper/graphics modes, which fits to the
6316. 4k (in the 6332) would have the normal us charset (both modes)
as well as the nationalized in the second half. 

I _assume_ from the the 8032 schematics that a CRTC video address
line is used to switch to the second, nationalized half.
Setting this bit on my 8296 (us, i.e. en = 50Hz) results in an
inverted blank screen (lots of $ff), i.e. no character data.
But setting it on the nationalized one could probably switch between
us and nationalized charsets (as the DIN key does in german C128 machines).

You can fiddle around with the video address lines by 
poke $e880,12: poke $e881, *
Try to find out about the initial value (see ROM) because it also 
might implement the video signal invert (which makes the electron beam work
on flyback...)

> Anyway I cannot check this with this 8032SK so I'll run to the livingroom and 
> check it with my German SK.......... No graphics on keyboard but produces them 
> as well. And this time it is the right keyboard! (A-umlaut, O-umlaut etc...)

Can you switch the character sets on the screen to normal (i.e. us) 
chars?

Thanks again
Andre

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Andre Fachat, Institute of physics, Technische Universitšt Chemnitz, FRG
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