Screensaver cmos bytes on risc os 4.39/six

Hi folks.

RISC OS 4 and 5 (and earlier) seem to use a standard cmos location for reading/writing the blank time (Misc1bits).

However, 4.39 and Six seem to allow for two times to be set – DPMS time and blank time. Neither seem to use Misc1bits address, as far as I can see.
Translation – my code seems OK on RISC OS 5, and reads/writes the cmos locations OK, but Adjust doesn’t seem to notice.

Does anyone have any more info on this that could point me in the right direction for those OS versions? (And yes, I know, this isn’t entirely the place, but it’s all we got!).

OS4.39 and OS6.20

See !Boot.Choices.Users.Single.Boot.Tasks.SvrSetup

Thanks David. I was semi-aware of that, but it suggests that 4.39 and six no longer use CMOS at all for this… Is that really the case?

Is that really the case?

It would make sense – such things can be set up in the boot sequence (if you don’t boot properly then screensavers probably wouldn’t work anyway!) which saves the problem of what to do with a resource that is as restricted as CMOS RAM.
After all, CMOS might hold the Econet station ID, but it doesn’t hold the machine’s IP address, name servers, or gateway…
Ideally, CMOS ought to be restricted in use for that which is absolutely necessary to get a functioning system started (language, monitor type (less relevant these days), default filesystem and drive, and so on) with all the other customisations being held in Choices.

Some examples of stuff that is not necessary to bring up the machine: bytes 15 ¹, 22, 23, 27, 28, 140, 197, 198, 220, 221, 222, and 223. Many of these are Wimp behaviour, there’s no reason it can’t be done in PreDesk.

¹ You can’t even say it might be useful for setting serial options for debugging, as that stuff is set up prior to CMOS even being looked at, and the CMOS value tops out at 19200 which is comically slow these days.

After all, CMOS might hold the Econet station ID, but it doesn’t hold the machine’s IP address

Bytes 108-110 would like a word with you :P

Admittedly the address isn’t stored there by default, but if you’ve set “Obtain IP address from CMOS” in your network configuration then that’s where it’ll look.

but it suggests that 4.39 and six no longer use CMOS at all for this… Is that really the case?

I found this in S3FEATURES/HTML on the 3i3 CD :-

“ScreenBlanker now supports a second-level blanking using DPMS. ScreenBlanker no longer uses CMOS to get its initial settings and defaults to ‘off’.”

Thanks David – that’s really great. I now have the software working nicely with both flavours of RISC OS.