MirrorRepos/RomWBW
1
0
Fork 1
mirror of https://github.com/wwarthen/RomWBW.git synced 2026-02-06 14:11:48 -06:00
Code Issues Projects Releases Wiki Activity

Documenation changes for the NVRAM changes

Browse Source
This commit is contained in:
Mark Pruden
2024-11-29 09:06:51 +11:00
parent f6ef90fe14
commit 9713ca445c
14 changed files with 879 additions and 602 deletions
Download Patch File Download Diff File Expand all files Collapse all files

113
Source/Doc/SystemGuide.md
View File

@@ -499,6 +499,77 @@ The startup then proceeds very much like the Application Boot
process described above. HBIOS is installed in its operating bank
and control is passed to the Boot Loader.
# Configuration
## RomWBW NVRAM Configuration
On systems with RTC devices (that have Non-Volitile RAM), RomWBW supports storing
some limited configuration option options inside this RAM
Several configuration options are currently supported, these are known as Switches
The following switch ID's are defined, and described in sections below
| Switch Number | Name | Description |
|---------------|--------------|-----------------------------------------------|
| 0x00 | -reserved- | Reserved |
| 0x01 | Default Boot | Default boot, either a Rom App or Disk Boot |
| 0x02 | -n/a- | -n/a- high order byte of previous switch |
| 0x03 | Auto Boot | Automatically boot enabled without user input |
| 0x04 - 0xFE | -future- | Future general usage |
| 0xFF | Status Reset | Get Status or Reset Switches to Default |
RomWBW uses bytes located at the start of RTC NVRAM, and includes a Parity check of
the bytes in NVRAM to check for authenticity before using the configuration.
| NVRAM Byte | Name | Description |
|-------------|--------------|-----------------------------------|
| 0x00 | Header Byte | Header Signature Byte 'W' |
| 0x01 - 0x03 | Switch Data | Actual Switch Data |
| 0x04 | Parity Check | Parity byte to check authenticity |
The above data is copied into HBIOS Configuration Block (HCB) at startup at
the loacation starting at CB_SWITCHES
### Default Boot (NVSW_DEFBOOT)
16 bit Switch defining the default Rom application or Disk device to boot.
| Bit 15 | Bits 14-8 | Bits 7-0 |
|-------------|-------------------|--------------------|
| 1 = Rom App | -undefined- | App to Boot (Char) |
| 0 = Disk | Disk Unit (0-127) | Disk Slice (0-255) |
### Auto Boot (NVSW_AUTOBOOT)
8 bit Switch defining if the system should auto boot at startup
| Bits 7-6 | Bit 5 | Bit 4 | Bits 3-0 |
|----------|------------------------|----------|--------------------------------------|
| -unused- | 1 = Auto Boot Enabled | -unused- | 0 = Immediate Boot with no delay |
| -unused- | 1 = Auto Boot Enabled | -unused- | (1-15) Timeout (seconds) before boot |
| -unused- | 0 = Auto Boot Disabled | -unused- | -undefined- |
### Status Reset (0xFF)
The Status Reset switch is not a general purpose switch, it is a control mechanism
to allow the global status of all switches to be determined. The meaning of the switch
is different for Read (Get Status) and Write (Reset NVRAM)
#### GET (Get Status)
The read Get Status of switches. This returns very specific values from the function call.
| Status | A Register | Z / NZ Flag |
|----------------------------------------------|------------|--------------|
| NVRAM does not exist | A=0 | NZ flag set |
| NVRAM exists, but has not been initialised | A=1 | NZ flag set |
| NVRAM exists, and has been fully initialised | A='W' | Z flag set |
#### SET (Reset NVRAM)
Reset NVRAM to default values. This will wipe any existing data and set default
values into NVRAM.
# Driver Model
The framework code for bank switching also allows hardware drivers to be
@@ -2611,6 +2682,27 @@ the caller can use interbank calls directly to the function in the
driver which bypasses the overhead of the normal function invocation
lookup.
#### SYSGET Subfunction 0xC0 -- Get Switches (SWITCH)
| **Entry Parameters** | **Returned Values** |
|----------------------|---------------------|
| B: 0xF8 | A: Status |
| C: 0xC0 | HL: Switch Value |
| D: Switch Key | |
This function will return the current value (HL) of the switch (D) from NVRAM.
Switches may be returned as a 16 bit (HL) or 8 bit (L) value. It is up to the caller
to process the returned value correctly. Note for Switch 0xFF (status) the returned value
is primarily in the Status (A) register.
Errors are signalled in the return by setting the NZ flag. When set the
(A) register may contain an error code, but this code does not conform to RomWBW standard
Success is indicated by setting the Z flag
For a description of switches please see [RomWBW NVRAM Configuration]
#### SYSGET Subfunction 0xD0 -- Get Timer Tick Count (TIMER)
| **Entry Parameters** | **Returned Values** |
@@ -2783,6 +2875,27 @@ sub-function value. The following lists the subfunctions available along
with the registers/information utilized. The Status (A) is a standard
HBIOS result code.
#### SYSSET Subfunction 0xC0 -- Set Switches (SWITCH)
| **Entry Parameters** | **Returned Values** |
|----------------------|---------------------|
| B: 0xF9 | A: Status |
| C: 0xC0 | |
| D: Switch Key | |
| HL: Switch Value | |
This function will set the value (HL) into the switch (D) and store it into NVRAM.
Switches may be passed as a 16 bit (HL) or 8 bit (L) value. It is up to the caller
to send the value correctly. Note for Switch 0xFF (reset) the value (HL) is ignored
Errors are signalled in the return by setting the NZ flag. When set the
(A) register may contain an error code, but this code does not conform to RomWBW standard
Success is indicated by setting the Z flag
For a description of switches please see [RomWBW NVRAM Configuration]
#### SYSSET Subfunction 0xD0 -- Set Timer Tick Count (TIMER)
| **Entry Parameters** | **Returned Values** |