OS_Byte 255
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» Part 15 – SWI Calls
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» OS_Byte 255
OS_Byte 255
(SWI &06)
| Entry | |
|---|---|
| R0 | 255 (&FF) |
| R1 | EOR value |
| R2 | AND value |
| Exit | |
|---|---|
| R0 | Preserved |
| R1 | Previous state |
| R2 | Corrupted |
Use
The purpose of this call is to read or set the current auto boot flag in OS_Byte CMOS Settings.
Notes
This call is deprecated. You should use OS_FSControl 10 instead.
If NoBoot is set, after a reset the computer isn’t automatically booted. If Boot is set, the boot file on the filing system is accessed on reset. To invert this setting, hold Shift down after releasing the reset keys. The bit 3 of R1 indicates the named option. Set means NoBoot, Clear means Boot.
Hum. Yes. This is what the PRM says, and it’s utter garbage.
This call reads or sets the soft copy, which defaults to the contents of the CMOS ram. But you can change it. And OS_FSControl 10 sets the boot option, which is something else (even if machine will try to boot, if the boot option on the disc is off, nothing happens.) OS_FSControl 10 cannot read anything. It’s write only.