Posted By
SVS
on 2016-11-12
14:31:13
 |  Bit# 4 of TEd register $14
Did you know that this bit is automatically set by the TED when it starts a Hires screen?
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Posted By
Mad
on 2016-11-12
14:57:45
| Re: Bit# 4 of TEd register $14
Tried it by clearing ff14 and then setting ff07 to multicolor and back to hires again. The only thing that happens here (yape emulator) is that ff14s lowes 3 bits become one (reading ff14 gets a $07 out of it). Would be interessting if your observation would be reproducible with other plus4 machines.
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Posted By
SVS
on 2016-11-13
07:54:52
| Re: Bit# 4 of TEd register $14
@Mad: try to set the FF14 to any legal text address (say $0C) and then perform GRAPHIC 2 or GRAPHIC 4. Test again $FF14 and you'll find $1C.
If you hit GRAPHIC 0 it will become $0C.
Even if I did not  I believe that the old masters did know this. It seems that to set Hires attributes address area to, say $7800, they had to write $6800 inside register $FF14 before to use the Hires.
Any further info is welcome
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Posted By
Luca
on 2016-11-13
08:02:35
 | Re: Bit# 4 of TEd register $14
I don't see any surprise in this.
If you're in charmode (GRAPHIC 0) the screen and color RAM to be read lie in $0800-$0FE7; if you're in any bitmap mode the chroma/luma RAM to be read lie in $1800-$1FE7, and bit 4 has to be obviously set. End of the story, I guess...
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Posted By
gerliczer
on 2016-11-13
08:16:36
| Re: Bit# 4 of TEd register $14
SVS,
Your two posts contradict each other. In the first one you talk about TED doing something automatically. In the second one you talk about BASIC commands. Well, these BASIC commands obviously perform some TED register changing, but that will never mean that it is done by TED automatically as you stated it in your opening post.
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Posted By
SVS
on 2016-11-13
11:14:56
| Re: Bit# 4 of TEd register $14
Sorry if I was not so accurate. Really I'm not a graphician coder 
I've cited the Basic behavior because it is easy to check, with Monitor commands, even when Hires is on.
I meant: being in char-mode, you set $68 in Register #14. Then you turn on a graphic-mode and TED read from $7800.
Right or wrong?
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Posted By
siz
on 2016-11-14
04:16:58
| Re: Bit# 4 of TEd register $14
I haven't checked it but - as stated by gerliczer earlier - it is NOT a TED behaviour. It's likely that BASIC will set the bitmap screen to the next available address and the color/luminance address to the one right below the bitmap but it's definitely not a TED automatism.
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Posted By
Luca
on 2016-11-14
04:36:50
| Re: Bit# 4 of TEd register $14
. C613 AD 14 FF LDA $FF14
. C616 29 03 AND #$03
. C618 09 18 ORA #$18
. C61A 8D 14 FF STA $FF14
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Posted By
SVS
on 2016-11-19
07:12:38
| Re: Bit# 4 of TEd register $14
Ok I re-checked it. I was wrong, sorry.
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