Layer 2 Access Port: Difference between revisions
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core 3.0 changes/refresh |
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| Line 2: | Line 2: | ||
|Number=$123B | |Number=$123B | ||
|ShortDesc=Enables [[Layer 2]] and controls paging of layer 2 screen into lower memory. | |ShortDesc=Enables [[Layer 2]] and controls paging of layer 2 screen into lower memory. | ||
|Readable= | |Readable=Yes | ||
|Writable= | |Writable=Yes | ||
|Subsystem=Layer 2 | |Subsystem=Layer 2 | ||
|PortMask=%0001 0010 0011 1011 ?? | |PortMask=%0001 0010 0011 1011 ?? | ||
}} | }} | ||
{| class="wikitable" | |||
! Bit !! Description | |||
|- | |||
| 7-6 || Video RAM bank select (write/read paging) | |||
|- | |||
| 5-4 || Reserved, write 0 | |||
|- | |||
| 3 || Use Shadow Layer 2 for paging - {{NextRegNo|$13}} | |||
|- | |||
| 2 || Enable Layer 2 read-only paging | |||
|- | |||
| 1 || Layer 2 visible - {{NextRegNo|$12}} | |||
Since core 3.0 this bit has mirror in {{NextRegNo|$69}} | |||
|- | |||
| 0 || Enable Layer 2 write-only paging | |||
|} | |||
Revision as of 19:17, 27 November 2019
| Number | PortNumber::$123B |
|---|---|
| Decimal | NumberDec:: |
| Short desc. | [[ShortDesc::Enables Layer 2 and controls paging of layer 2 screen into lower memory.]] |
| Bit Mask | [[PortMask::%0001 0010 0011 1011 ??]] |
| Readable | Readable::Yes |
| Writable | Writable::Yes |
| Subsystem | Subsystem::Layer 2 |
| Bit | Description |
|---|---|
| 7-6 | Video RAM bank select (write/read paging) |
| 5-4 | Reserved, write 0 |
| 3 | Use Shadow Layer 2 for paging - {{#ask:
TBRegisterNumber::$13 }} ($13) |
| 2 | Enable Layer 2 read-only paging |
| 1 | Layer 2 visible - {{#ask:
TBRegisterNumber::$12 }} ($12) Since core 3.0 this bit has mirror in {{#ask: TBRegisterNumber::$69 }} ($69) |
| 0 | Enable Layer 2 write-only paging |