Path: utzoo!utgpu!watmath!clyde!att!osu-cis!killer!ames!mailrus!iuvax!uxc!tank!nucsrl!accuvax.nwu.edu!bob
From: bob@accuvax.nwu.edu (Bob Hablutzel)
Newsgroups: comp.sys.mac
Subject: Re: Tough Ramdisk?
Message-ID: <10330111@accuvax.nwu.edu>
Date: 10 Jan 89 13:47:22 GMT
References: <30519@cs.tcd.ie>
Organization: Northwestern U, Evanston IL, USA
Lines: 22

> I was doing some programming on Amigas recently and the only thing that kept
> me from going insane was a really nice Ramdisk that survived resets. I would
> really, really like something similarly tough for the Mac. Y'see, I'm using
> Lightspeed C 3.01 from floppies and turnaround time is less than stunning.
> I'd like to compile to ram, or put Lightspeed itself there, or something,
> depending on memory limitations. I'm currently working on a 1M Mac+, but I
> may be expanding this. So, anyone know of a Ramdisk that survives DS errors,
> generally, and, ideally, is size-configurable?

I doubt this can be done with the Mac except with dedicated external hardware.
The problem is that the top of memory mark is reset at each startup, to the
physical top of memory. The RAM disk would have no control over the possible
overwritting of it's data before the RAM disk INIT executed.

On the external hardware side, it would be fairly easy. Matter of fact, I
remember a Q-Bus board (for PDP-11/x3 machines) which emulated RX01 drives
with bubble memory. This gained you a persistant drive at bubble memory 
speeds. (Note - bubble memory is considerably slower than memory we're used
to, at least the last time I looked). No recollection about the speed/price/
manufacturer. And no idea if a similar puppy exists for the Mac.

Bob Hablutzel	BOB@NUACC.ACNS.NWU.EDU