[stella] PCAE has 263 Scanlines?
Subject: [stella] PCAE has 263 Scanlines?|
From: Rodrigo <stella@xxxxxxxxxxxxx>
Date: Sun, 18 Aug 2002 14:32:45 -0300
PCAE is puzzling me (and ruining my cycle/scanline counting as
In its debugger there's a "Scan" (CY, CRT beam Y
) variable that is supposed to help the programmer to know
in which scanline TIA (and the TV) is. Its value ranges from -40 to 222,
which sums up to 263 scanlines. But, according to SPG, 3 Vsync + 37
Vblank = 40 (hence the -40 range in Scan). 192 visible scanlines + 30
Overscan = 222. And, finaly, 40+222=262. It seems that PCAE has an extra
Is that true? if so, where this "extra scanline" belongs to? To
the overscan? to VBlank? What about Z26? (Im asking about Z26 because the
same accuracy problems that led me to this question occured in Z26 too...
unfortunatly it has no Debug mode to count scanlines)