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Wayne Warthen
2024-01-24 16:31:25 -08:00
parent a00cf821c7
commit b633c309f4
10 changed files with 33 additions and 20 deletions
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Source/Doc/SystemGuide.md
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@@ -1992,11 +1992,11 @@ If the system is using interrupt mode 1 interrupts, the you **must**
take steps to ensure interrupts are properly handled. You generally
have two choices:
- Disable interrupts while the normal user bank is switched out
- Duplicate the interrupt mode 1 vector from the normal user bank
- Disable interrupts while the User Bank is switched out
- Duplicate the interrupt mode 1 vector from the User Bank
into the bank you are switching to.
If the normal user bank has been switched out, you will not be able to
If the User Bank has been switched out, you will not be able to
invoke the HBIOS API functions using an `RST 08` instruction. You can
use the alternative mechanism using `CALL $FFF0` as described in
[Invocation].
@@ -2398,7 +2398,8 @@ concept of allocation of application banks must be implemented within
the OS or application.
This function does not change the current bank selected. You must use
[Function 0xF2 -- System Set Bank (SYSSETBNK)] or ???? for this. Be sure
[Function 0xF2 -- System Set Bank (SYSSETBNK)] or the proxy function
[Bank Select (BNKSEL)] for this. Be sure
to observe the warnings in the description of this function.
### Function 0xF9 -- System Set (SYSSET)
@@ -2629,17 +2630,32 @@ provided.
## Proxy Functions
The following special functions are implemented inside of the HBIOS
proxy area at the top of RAM. They do not cause a bank switch are are,
proxy area at the top of RAM. They do not cause a bank switch and are,
therefore, much faster than their corresponding HBIOS API functions.
The functions are invoked via the following dedicated jump table:
| **Function** | **Address** |
|----------------------------------------|----------------------------------------|
| Invoke HBIOS Function (INVOKE) | 0xFFF0 |
| Bank Select (BNKSEL) | 0xFFF3 |
| Bank Copy (BNKCPY) | 0xFFF6 |
| Bank Call (BNKCALL) | 0xFFF9 |
| **Function** | **Address** | ** Equate ** |
|----------------------------------------|---------------|------------------------|
| Invoke HBIOS Function (INVOKE) | 0xFFF0 | HB_INVOKE |
| Bank Select (BNKSEL) | 0xFFF3 | HB_BNKSEL |
| Bank Copy (BNKCPY) | 0xFFF6 | HB_BNKCPY |
| Bank Call (BNKCALL) | 0xFFF9 | HB_BNKCALL |
The function addresses are also defined as equates in hbios.inc. It
is suggested that you use the equates when possible.
To use the functions, you may either call or jump to them. Some
examples:
```
CALL $FFF0
JP $FFF3
CALL HB_BNKCPY
```
These functions are inherently dangerous and generally not value
checked. Use with extreme caution.
### Invoke HBIOS Function (INVOKE)
@@ -2651,9 +2667,6 @@ above. To put it another way, `CALL $FFF0` is equivalent to `RST 08`,
but it can be used in any scenario when the normal bank is not
selected.
These functions are inherently dangerous and generally not value
checked. Use with extreme caution.
### Bank Select (BNKSEL)
**Address 0xFFF3**
@@ -2663,9 +2676,9 @@ checked. Use with extreme caution.
| A: Bank ID | |
This function will select the memory bank identified by Bank ID (A).
All registers are preserved.
Register AF is destroyed. All other registers are preserved.
The warnings described in [Function 0xF3 -- System Get Bank (SYSGETBNK)]
The warnings described in [Function 0xF2 -- System Set Bank (SYSSETBNK)]
should be observed.
### Bank Copy (BNKCPY)
@@ -2716,7 +2729,7 @@ Register usage is determined by the routine that is called.
Since a different bank will be selected while the target function is
active, the warnings described in
[Function 0xF3 -- System Get Bank (SYSGETBNK)] should be observed.
[Function 0xF2 -- System Set Bank (SYSSETBNK)] should be observed.
`\clearpage`{=latex}