VT and 8x8 Attributes: Vague wording

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Hamtaro126
Posts: 777
Joined: Thu Jan 19, 2006 5:08 pm

VT and 8x8 Attributes: Vague wording

Post by Hamtaro126 » Sun Feb 21, 2021 7:18 pm

I am doing some project with VT0x when I came across some vague wording how to write 8x8 attributes. only example or something to do about it is very vague:
On the original NES/Famicom, and on the VT02+ with Address Extension Disabled, both background and sprite tiles are indexed by an eight-bit number taken from the nametable for backgrounds and byte 1 of each sprites' OAM data. Address Extension adds three bits to form an eleven bit tile number, which can be seen as performing an implicit bankswitch for each tile. VR Technology's VT03 Demonstration ROM uses Background Address Extension to show off the use of more than 256 Hanzi characters on a single page
There is no other info on how those three bits can be interacted with, so I am guessing people are assuming from the documentation and/or ROMS and nothing else.

And please: How does one operate 8x8 attributes on VT systems? I would really appreciate an answer, thank you!

EDIT: 777th post!!! WOO!!!
AKA SmilyMZX/AtariHacker.

lidnariq
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Re: VT and 8x8 Attributes: Vague wording

Post by lidnariq » Sun Feb 21, 2021 7:31 pm

Right below the portion of the wiki that you quoted, it says:
Background Address Extension is enabled by setting register $2010 bit 4 (BKEXTEN). The three bits of the Extended Video Address are derived as follows: [...]
Since the two bits from the attribute table are now used as part of the tile number, they are forced to zero when forming the final palette index of each pixel.
(emphasis mine)

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