SCROLL and ZxPrinter bug.

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XavSnap
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SCROLL and ZxPrinter bug.

Post by XavSnap »

Code: Select all

1 FOR A=0 TO 15
2 PRINT AT 20,10;"HELLO WORLD"
3 SCROLL
4 SCROLL
5 NEXT A
6 COPY
:shock:

COPY can't be use on a compressed D_file !
And SCROLL can't be use with a COPY command.
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
bola_dor
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Re: SCROLL and ZxPrinter bug.

Post by bola_dor »

XavSnap wrote: Sat Dec 05, 2020 8:02 pm

Code: Select all

1 FOR A=0 TO 15
2 PRINT AT 20,10;"HELLO WORLD"
3 SCROLL
4 SCROLL
5 NEXT A
6 COPY
:shock:

COPY can't be use on a compressed D_file !
And SCROLL can't be use with a COPY command.
Wow. Never tried it.. what would be the behavior?
Ernesto
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come :D
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XavSnap
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Location: 'Zx81 France' Fb group.

Re: SCROLL and ZxPrinter bug.

Post by XavSnap »

Hi,
Just a printing routine bug… the COPY is based on a 16k 20x32 screen setup…
On a 1k or 2k configuration, it's the same problem.

The SCROLL routine don't rebuild the 16k memory D_File and don't fill the screen while it's process.

In case of COPY in 1k, it print the 118 character as a displayable character !
:mrgreen:

The Copy routine isn't designed to run on a 1k computer !
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
bola_dor
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Re: SCROLL and ZxPrinter bug.

Post by bola_dor »

Thanks.. That’s good to know
Ernesto
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come :D
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stefano
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Re: SCROLL and ZxPrinter bug.

Post by stefano »

Uh, I studied the copy routine and I never thought at this limit.
The ZX Printer and compatibles need a precise timing to sync the data to be outputted and the printing needle, I'm quite sure that even the tractor feed deceleration is compensated in the program loop (every 8 dot lines, thus a full text row).
I clearly remember the row/line counters(it expects full heigth), but honestly I'm not sure on how the line termination is checked.
I think it is dynamic in size, I'm quite sure LPRINT and LLIST will work with 1K.
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stefano
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Re: SCROLL and ZxPrinter bug.

Post by stefano »

0869 COPY LD D,+16
LD HL,+D-FILE
INC HL
JR 0876,COPY*D

16 hex=22 text lines. By the way, the collapsed D-FILE includes all the text line terminations.
I don't see the bug, in the code.. yet it's not the simpler routine :D
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stefano
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Re: SCROLL and ZxPrinter bug.

Post by stefano »

Is the collapsed D-FILE making the COPY command fail also without the SCROLL interference?
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