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From: sl@van-bc.UUCP (Stuart Lynne)
Newsgroups: comp.sys.mac
Subject: Re: DIY SCSI... It's done!
Message-ID: <1355@van-bc.UUCP>
Date: Mon, 21-Sep-87 02:43:28 EDT
Article-I.D.: van-bc.1355
Posted: Mon Sep 21 02:43:28 1987
Date-Received: Tue, 22-Sep-87 01:24:41 EDT
References: <1479@imagen.UUCP> <3898@sdcsvax.UCSD.EDU>
Reply-To: sl@van-bc.UUCP (Stuart Lynne)
Organization: Public Access Network, Vancouver, BC.
Lines: 42

In article <3898@sdcsvax.UCSD.EDU> jww@sdcsvax.UCSD.EDU (Joel West) writes:
>In the September batch of Tech Notes, #159 finally addresses
>the issue of "How do I build my own SCSI drive?"  I would say,

.... misc. warnings etc deleted to save space

>This may sound like it is hard to write your own
>driver.  It is.  This may sound like we are trying
>to scare you off from writing your own driver.  We are.

I built my own when the Mac Plus first came out. While they make some
obvious points about the difficulty involved they are going overboard a bit.
I make no pretense to being Joe C/Asm Hacker, don't know +5 from ground and
had never worked with SCSI.

It took me less than two weeks to get something useable. Some of *that* time
was implementing the SCSI driver hooks (this was late '85, before you get
get the libraries etc from Apple or anyone else); and debugging Apple's ROM
driver to get Blind transfer's to work. 

Given the level of knowledge available about the subject matter, and
availability of misc. bits of software I don't think that anyone with
reasonable programming skills shouldn't attempt this *if* they want to have
some fun and learn something about how drivers work with the Mac.

Basically this project is fun because *it is* moderately difficult in spots,
but without any huge amounts of drudge. As a learning tool it's fun and you
do end up getting yourself a drive for about half price. (E.g. pick up a
Seagate ST225N for about $400, last time I checked, probably cheaper now!)

Start with one of the RAM disk's available. The SCSI code slot's right in.
Formatting is usually a matter of issuing one or two commands to the drive
via the SCSI manager. You will probably want to implement a simple program
to right the boot blocks on the drive so you can auto-boot.

Good luck and have fun. 

PS. I use a Dataframe these days.. provided by my employers.


-- 
{ihnp4!alberta!ubc-vision,uunet}!van-bc!Stuart.Lynne Vancouver,BC,604-937-7532