Date   : Sat, 20 Aug 2011 23:21:04 GMT
From   : jgh@... (J.G.Harston)
Subject: Tube ROM

Rick Murray wrote:
> I was wondering what is on the 6502 co-processor EPROM. I've not pulled
> it to read it, as I think I've found a copy in BeebEm:
>    ...BeebEm\UserData\BeebFile\6502Tube.rom

Commented source code at http://mdfs.net/tube/6502

> It's only 2K!
> Somehow, I expected it to be larger...

It doesn't take much code to pass the MOS API over a connection to
a host. Tube clients for most CPUs can be written in about 1K of
code, additional code is usually to add things like a few extra
client-side *commands and client-specific *HELP responses.

> A question I have is if HiBASIC is present as a BBC Micro EPROM, but it
> won't work unless it is copied onto the co-processor, why is it not part
> of the co-processor firmware, and just copied into RAM at startup? It's

Because a second processor is just that - a second processor. You
may as well ask why HiVIEW or HiEDIT isn't in the 6502 second
processor. A second processor executes whatever code the I/O
processor tells it to, sent to it either from ROM or from a filing
system.

Also, languages aren't part of any bit of Acorn firmware, they are
applications. The MOS is the firmware, whatever languages you chose
to use on your system is down to you.

-- 
J.G.Harston - jgh@...      - mdfs.net/jgh
There are three food groups: brown, green and ice cream.