Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.3 alpha 4/3/85; site ukecc.UUCP
Path: utzoo!watmath!clyde!cbosgd!ukma!ukecc!crowe
From: crowe@ukecc.UUCP (Donald "Deke" Crowe)
Newsgroups: net.micro.mac
Subject: Re: MacSCSI board query
Message-ID: <284@ukecc.UUCP>
Date: Mon, 14-Oct-85 17:22:16 EDT
Article-I.D.: ukecc.284
Posted: Mon Oct 14 17:22:16 1985
Date-Received: Wed, 16-Oct-85 05:05:01 EDT
References: <2469@ut-ngp.UTEXAS>
Distribution: net
Organization: Univ. of Ky. Engineering Computing Center
Lines: 32

In article <2469@ut-ngp.UTEXAS>, rick@ut-ngp.UTEXAS (Rick Watson) writes:
> A quick query regarding the MacSCSI interface described in the September
> Dr. Dobbs:  Has anyone successfully built an interface from scratch?  If
> so, what changes did you make to the schematic?  For starters: 1) I
> think the pin labeled A11 on the rom should be labeled A16. 2) No
> termination is shown for the SCSI bus. 3) Experimenting with a board
> delivered from Fastime seems to indicate that BSY and ATN are not shown
> correctly on the schematic.
> 
> Also, has anyone figured out if the address space of the board is going
> to collide with the address space of the new roms?
> 
Some of us at U of Ky are doing three of these hard disk systems and we have 
already etched the boards and assembled the disk controllers, etc.  Now we are 
all worried that the Dobb's article has some typos.  We noticed at first that
the address decoding doesn`t make a great deal of sense.  But decoding can be
done a million different ways and still work.  We have talked to John Bass at 
Fastimes and he says the new ROMs will not work.  This is logical because the 
new ROMs will be decoded where the SCSI board is being addressed.  There is no
way to get around this because there are no more address lines available from
the ROM sockets.  You would have to pull lines from elsewhere(68000) to decode.

If anybody has built this or has the fastimes board, could you please tell all
of us if this thing will work as is?  If so please post the corrections as 
soon as possible.  For anyone interested, we will post our results and where
we got our parts.  We think we have some good sources of low price parts.
Our price for a complete 5M hard disk is about $375.  Not too bad!!!



						D Crowe
					cbosg!ukma!ukecc!crowe