Difference between revisions of "OSBYTE &6C"
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OSBYTE &6C (108) - Main/Shadow RAM access | OSBYTE &6C (108) - Main/Shadow RAM access | ||
| − | + | On entry: | |
| − | + | X=0 Main memory appears from &3000 to &7FFF | |
| + | X=1 Shadow memory appears from &3000 to &7FFF | ||
| + | On exit: | ||
| + | X=previous state | ||
| − | This has immediate effect and allows the user to access the Master | + | This has immediate effect and allows the user to access the Master shadow |
| − | + | RAM, for instance, to load or save it or manipulate it directly. The memory | |
| − | + | that is accessed by the Master VDU drivers and displayed can set with | |
[[OSBYTE &70]] and [[OSBYTE &71]]. | [[OSBYTE &70]] and [[OSBYTE &71]]. | ||
| + | |||
| + | Shadow RAM on the BBC B with the Integra-B system is also paged in with | ||
| + | OSBYTE &6C. The Aries and Watford systems use [[OSBYTE &6F]]. | ||
On the BBC B+ the displayed memory is always the bank selected with MODE or | On the BBC B+ the displayed memory is always the bank selected with MODE or | ||
| Line 15: | Line 21: | ||
==See Also== | ==See Also== | ||
| − | * [[OSBYTE &6C]] - Select Master shadow memory | + | * [[OSBYTE &49]] - Check for Integra-B shadow memory |
| + | * [[OSBYTE &6C]] - Select Master/Integra-B shadow memory | ||
* [[OSBYTE &6F]] - Select BBC B shadow memory | * [[OSBYTE &6F]] - Select BBC B shadow memory | ||
* [[OSBYTE &70]] - Select memory for Master VDU access | * [[OSBYTE &70]] - Select memory for Master VDU access | ||
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* http://mdfs.net/Docs/Comp/BBC/Osbyte00 | * http://mdfs.net/Docs/Comp/BBC/Osbyte00 | ||
| − | [[User: | + | [[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 20:27, 3 April 2015 (UTC) |
Revision as of 22:27, 3 April 2015
OSBYTE &6C (108) - Main/Shadow RAM access
On entry: X=0 Main memory appears from &3000 to &7FFF X=1 Shadow memory appears from &3000 to &7FFF On exit: X=previous state
This has immediate effect and allows the user to access the Master shadow RAM, for instance, to load or save it or manipulate it directly. The memory that is accessed by the Master VDU drivers and displayed can set with OSBYTE &70 and OSBYTE &71.
Shadow RAM on the BBC B with the Integra-B system is also paged in with OSBYTE &6C. The Aries and Watford systems use OSBYTE &6F.
On the BBC B+ the displayed memory is always the bank selected with MODE or OSBYTE &72, and the user can only access the shadow memory by calling OSRDSC.
See Also
- OSBYTE &49 - Check for Integra-B shadow memory
- OSBYTE &6C - Select Master/Integra-B shadow memory
- OSBYTE &6F - Select BBC B shadow memory
- OSBYTE &70 - Select memory for Master VDU access
- OSBYTE &71 - Select memory for Master video display
- OSBYTE &72 - Select future use of shadow memory
- OSBYTE &73 - Select shadow bank
- OSBYTE &74 - Check for Solidisk shadow memory
- Paging in video memory
- http://mdfs.net/Docs/Comp/BBC/Osbyte00
