Posted By
Csabo
on 2006-07-21
13:08:10
|  Re: MY YAPE BUG IS CAPTURED!!! (I'm not crazy. Phew.)
Well...
You guys know about the fact that if you modify anything on screen (e.g. writing characters to the screen), these operations should not be done at the same time when the machine is actually displaying those characters? When I said "should not be done" - if you want smooth display that is. The built in MONITOR or BASIC was not designed with this in mind, a lot of commands print stuff on screen at any "random" time, regardless of where the current vertical raster position is.
This effect can easily be reproduced:
A1100 SEI
LDA #$01
STA $FF0C
LDA #$56
CMP $FF1D
BNE $1108
INC $FF0D
JMP $1108
G1100
Now simply press pagedown in YAPE. When the cursor reaches line $56, you will see the exact same effect. It's no surprise: we're modifying the cursor position exactly at the same time as the TED is rendering it.
So... This is not a bug, it's just a simple side effect of MONITOR and BASIC not being a double-buffered, demo-quality application  Sure, most of us have probably seen this, but ignored it. Cool?
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