Re: PRODOS in ROM chip; boot from ROM

[dempson@actrix.gen.nz (David Empson)]

stephen e buggie <buggie@musca.unm.edu> wrote:

> I am setting up a Mac SE/30 to connect to the college Ethernet.  I need
> to do it this way because I get locked out of e-mail at every college
> vacation interval because at present, all e-mail is via pee cee klones in
> a college classroom.
> 
> A technician told me that the Mac launches its desktop from a system 
> stored in ROMs; it does not need disk access or hard drive access.

Well, not really - it cannot do anything useful until it reads the
system file, etc. from the boot disk.

It is true that the file system and most of the system software is in
the ROM.

> PRODOS IIe/IIc is only about 35K or 35 blocks; this could easily fit on a
> ROM.

Yes.

> Since there are no more recent Prodos-8 versions other than v.2.0.3, 
> could Prodos be placed on a ROm for super-fast booting???

Possibly.  ProDOS cannot actually _run_ from a ROM, as the in-memory
image contains several data structures which are updated.  You could put
the PRODOS file into a ROM disk, and boot from that.

The main question: where does this ROM go?  You would need yet another
card to contain the ROM.  This card would act as a ROM disk (it would
look pretty much like a RAM card).

If you wanted to go further than this, e.g. by patching the main ROM to
load ProDOS directly, then you would break booting other devices or
other operating systems, and you still have the problem of where to put
this extra ROM.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand