What does HM mean in the Stella TIA Debug Colors?

[lucienEn]

Hi, I'm trying to understand how Activision is skipping the first 8 pixels on each scanline. When I debug Pitfall I noticed it says HM in that area. What does that mean and how is this achieved? I tried stepping through the code but not seeing anything obvious how that is set.

[+splendidnut]

HM = HMOVE bar... Whenever HMOVE is triggered at the beginning of a line... it blanks out the first 8 pixels.

[lucienEn]

Thanks! That seems then easiest way to blank out the first 8 pixels and avoid the line chipset issue.

[glurk]

32 minutes ago, lucienEn said:

Thanks! That seems then easiest way to blank out the first 8 pixels and avoid the line chipset issue.

It's VERY common in Activision games.  They wanted to NEVER have HMOVE bars, so their games normally strobe HMOVE on every line.  In the places where they can't, they often use the ball (colored black) to hide the pixels.  They did this is pretty much every single game...