Gameboy Development Forum

There is this caution in Pan Docs (http://gbdev.gg8.se/wiki/articles/Video … lay_Enable):

CAUTION: Stopping LCD operation (Bit 7 from 1 to 0) may be performed during V-Blank ONLY, disabeling the display outside of the V-Blank period may damage the hardware. This appears to be a serious issue, Nintendo is reported to reject any games that do not follow this rule.

However, in the official Nintendo Game Boy Programming Manual (version 1.0, released 11/09/1999) it's not mentioned that it can cause any hardware damage:

2. PROGRAMMING CAUTIONS REGARDING GAME BOY
<...>
2.1.1 Setting the LCDC to OFF (Recommended)
Covers: DMG and CGB
In early DMGs, a black horizontal line appears on the screen if the LCDC is stopped (LCDC register bit 7 <- 0) at any time other than during vertical blanking. Therefore, the LCDC should be set to OFF during V-blanking. If the occurrence of V-blanking cannot be confirmed, the LCDC should be set to OFF when the value of the LY register is 145 (0x91) or greater. These restrictions do not apply in CGB. <...>

(Note that it says 'Recommended'. Some other cautions are 'Required', but not this one)

In the end, which one is correct?

Last edited by deeplinks (2015-03-16 01:58:24)