[Rpcemu] A pleasant blue window...
ralph at inputplus.co.uk
Sun Mar 21 17:33:44 PDT 2010
> The 3.71 rom works, as does the 'vanilla' 3.70 rom image I extracted
> from this RPC after a power on with shift & * (??) held down - the
> sha1sum of which equalled that of Ralph's so I know it's okay.
> At least this long sorry saga has highlighted the possible problem of
> patched rom images causing startup errors, and possibly running
My guess is the blue screen is RISC OS detecting that some internal
checksum on the ROM isn't correct during POST. That vaguely rings a
bell on other earlier emulators. (So much gets learnt, forgotten, and
has to be re-learnt!) Perhaps it needs to be mentioned somewhere in the
rpcemu FAQ/troubleshooting section? Along with a link to known good
SHA1 digests. :-)
Would it be nice if rpcemu looked at the ROM image provided and gave a
warning it if wasn't recognised? Digging out the "MOS Utilities"
version and seeing if that matched the expected CRC-32-IEEE 802.3 may
stop these kind of issues. I say CRC-32 rather than SHA1 because it's
still good enough but much easier to compute in code. And it's what the
POSIX cksum(1) command gives too.
$ cksum *
1806840565 4194304 david
212344744 4194304 davidwife
2820737424 4194304 musus
2453876003 4194304 mybad
3184921365 4194304 mygood
3728305141 4194304 rolf3.60
4102711502 4194304 rolf3.71
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