Date   : Fri, 18 Nov 2005 02:58:57 +0000
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re: Best Emulator??

Jonathan Graham Harston wrote:
>> Message-ID: <1132229969.1702.9.camel@...>
>  
> Jules Richardson <julesrichardsonuk@...> wrote:
>> This purely on the Master? I seem to recall the BBC B SCSI board being
>> significantly more complex than the Master one, or at least in terms of
>> chip count.
>  
> Early scis cards may have been more complex, but as far as the
> hardware API is concerned, they are the same. Data register at
> &FC40, status register at &FC41, control register at &FC42. I
> think it can be done in twelve or fourteen ICs.

I don't remember the Master one being more than half that number though, 
although I could be wrong.

I think my homebrew SASI controller came out as 8 chips though - with enough 
spare gates to add the extra SCSI gubbins if needs be.

I've never actually taken either of the Acorn BBC B versions that I have apart 
(as I'm sure you know, they're buried beneath the SCSI/ST506 bridge boards), 
but it looks like significantly more chips that the Master has.

>> I believe that the SCSI controller in the Viglen BBCs is different yet
>> again, plus of course Torch made both a SASI and SCSI controller for the
>> BBC... so there's at least 5 different flavours out there!

On a somewhat related note, a Cumana 68008 copro turned up today quite by 
chance (just after I'd mentioned them a few weeks ago too, and thought I'd 
never see a live one!). Turns out that has a built-in SASI interface on it, 
which I didn't realise.

So that's technically another SCSI/SASI controller to add to the pile...

> Yep! I haven't scanned in my Torch schematics yet. I'll put them
> on my "to-do" list.

I *think* I have mine scanned already for their drive controllers - I should 
really plonk them somewhere! I want to actually create a proper Torch-related 
corner of the web though rather than bunch them in with a load of Acorn stuff 
(so I can put all the relevant ROM dumps, other Torch schematics, and disk 
images all in the same place). Of course wanting and finding the time to do it 
are two different things! :-)

Incidentally, I'm pretty sure I don't have schematics for either flavour of 
the Torch Z80 boards on the offchance that you do? (also missing Quad X 
schematics but I doubt they exist anywhere these days!)

cheers

Jules