Difference between revisions of "Layer 2 RAM Page Register"
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|ShortDesc=Sets the [[Memory map|bank]] number where Layer 2 video memory begins. | |ShortDesc=Sets the [[Memory map|bank]] number where Layer 2 video memory begins. | ||
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Bits 5-0 store the number of the "SRAM page" (ie, [[Memory map|bank]]) used for the standard Layer 2 screen. The default is 8. Because the layer 2 screen is 48k, it actually occupies 3 banks, and the number set here is the first; so by default, it occupies banks 8-10. | Bits 5-0 store the number of the "SRAM page" (ie, [[Memory map|bank]]) used for the standard Layer 2 screen. The default is 8. Because the layer 2 screen is 48k, it actually occupies 3 banks, and the number set here is the first; so by default, it occupies banks 8-10. | ||
For shadow bank paging see [[Layer_2]] | For shadow bank paging see [[Layer_2]] | ||
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| + | Note that this register uses the 16kb bank method, so if you set Nextreg $12,$C if you need to read the contents via 8kb banks you would need to multiply x 2 | ||
Revision as of 03:21, 9 November 2018
| Number | $12 |
|---|---|
| Readable | Yes |
| Writable | Yes |
| Short Description | Sets the bank number where Layer 2 video memory begins. |
Bits 5-0 store the number of the "SRAM page" (ie, bank) used for the standard Layer 2 screen. The default is 8. Because the layer 2 screen is 48k, it actually occupies 3 banks, and the number set here is the first; so by default, it occupies banks 8-10.
For shadow bank paging see Layer_2
Note that this register uses the 16kb bank method, so if you set Nextreg $12,$C if you need to read the contents via 8kb banks you would need to multiply x 2