Date   : Tue, 23 Aug 1994 12:16:03 +0100
From   : jfid@... (James Fidell)
Subject: Re: Mine did something! Eeek!

lamcw wrote:

> beeb snapshot formats were discussed a while back. naturally the contents
> of the paged io needs to be dumped but what is dumped will depend on
> how you emulate the hardware. therefore to get one snapshot to work on
> more than one emulator is probably unlikely unless an overall strategy is
> agreed upon.

My proposed snapshot format does allow for all hardware register contents
and some status information to be stored.  If it is insufficient for
any particular emulator implementation then I'd suggest that we discuss
it and extend the specification so that we've covered all of the
possibilities.

Since we are all emulating the same hardware, it ought to be possible
to re-generate the machine state from the same information.

> my philosophy for handling the paged io is to do all the emulation when
> values are STORED to sheila. therefore any reads from sheila will be 
> correct and one does not need to 'intercept' the read.

I'm not sure about this.  It's theoretically possibly for the data to
change between the write and a subsequent read, even if it's unlikely
(which would probably depend upon you're emulator implementation).

> a really invaluable (but somewhat unheard of) book is 'guide to the bbc
> roms' by don thomasson, published by melbourne books. there wasn't a hope
> in hell of me getting this far without it.

I haven't seen this, even though my boss has promised me several times
that he'd let me borrow it.  What's it like ?

James.

-- 
 "Yield to temptation --             |
  it may not pass your way again"    |     jfid@...        
                                     |
        - Lazarus Long               |              James Fidell