stunstall
Posts: 7
Joined: Sun Apr 09, 2017 1:10 pm

Galaxian hardware

Tue Mar 20, 2018 5:34 pm

Hi, I am looking for details on Galaxian (1979) hardware.

The memory map as detailed in MAME4ALL and HistoricMAME has a very brief memory map for OBJRAM, but is there anything more extensive?

is there a guide on the sprite hardware and attribute RAM? (Especially the sprite hardware) - believe me, I have Googled :mrgreen:

Reading the very brief MAME info in the Galaxian driver I have determined that each sprite takes up 4 bytes in a region of OBJRAM, and in the 4 bytes there is XPOS, YPOS values, and XFLIP and YFLIP bits.

How is the image selected? Is it encoded a value from, say, 0-255?

Where does the sprite data reside in ROM? (the actual memory addresses)

Are the sprites rotated 90 degrees like the screen?

Also, I've tinkered with the character map, but am unsure how you tell a column to scroll vertically, as Galaxian does to move the enemies and introduce enemies on the score table.

Regards,
Scott

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