Xref: utzoo comp.unix.wizards:6023 comp.arch:3090
Path: utzoo!utgpu!water!watmath!clyde!ho95e!wcs
From: wcs@ho95e.ATT.COM (Bill.Stewart)
Newsgroups: comp.unix.wizards,comp.arch
Subject: Re: Jerry Pournelle on UNIX (From BYTE)
Keywords: ROMable UNIX
Message-ID: <1958@ho95e.ATT.COM>
Date: 9 Jan 88 05:12:50 GMT
References: <1495@osiris.UUCP> <2126@haddock.ISC.COM> <1497@osiris.UUCP> <3100@phri.UUCP>
Reply-To: wcs@ho95e.UUCP (46323-Bill.Stewart,2G218,x0705,)
Organization: AT&T Bell Labs 46133, Holmdel, NJ
Lines: 29

In article <3100@phri.UUCP> roy@phri.UUCP (Roy Smith) writes:
:	The proposal is to put Unix (the kernel and/or root file system) in
:ROM.  The problems are that it's hard to change and there may be problems
:with mounting a writeable filesystem on a read-only root.

A long, long time ago, in a laboratory not very far away, when we might
have still been the Phone Company, I met a laptop UNIX machine that was
hoping to be given the name 3B1.  It had UNIX in ROM, an LCD screen,
a WE32000 chipset, and a case that looked suspiciously like a TI745.
It never became a product; the economics weren't right, LCD, RAM, and
the 32000 were still too expensive and the marketing people weren't
sure if they could sell it.  It was wonderful anyway, even if it did need AC.

:	As for the first problem, why not use eeprom?  It's non-volatile,
:so you get almost-instant boots, but you can still write in it if you have
:to under program control for updates.

	The ROMs lived in a pod that clomped on the back, and were easy
to change, though a realistic physical design would probably put them
inside.  EEPROM might be a nice alternative, though for safety it might
be worth adding a backup ROM in case youtrash the EEPROM.

:	As for the second problem, I doubt it's a problem.  ...... ro /usr.

Minix takes the rather nice approach of making root a RAM disk.  You
can get a writable root even though the files come from ROM.
-- 
#				Thanks;
# Bill Stewart, AT&T Bell Labs 2G218, Holmdel NJ 1-201-949-0705 ihnp4!ho95c!wcs