UNIX pc 2nd drive modifications (was Re: P5.1 upgrade instructions)

[Jan Isley]

In article <924 at icus.islp.ny.us>, lenny at icus.islp.ny.us (Lenny Tropiano) writes:
> In article <792 at bagend.UUCP> jan at bagend.UUCP (Jan Isley) writes:
> ...
> |>After much deliberation and the soon to be released 2nd disk drive upgrade
> |>that will require this modification, ...
> ...
> Soon to be released?  The ICUS plans have been out for 6 months now.  I assume
> you are talking about John Milton's soon-to-be-released board.  As far as

Okay, okay, okay.  Yes, I was talking about John Milton's soon-to-be-released
board.  Since the ICUS board has been released it is not 'soon-to-be-released'.
You are certainly right in pointing this out.  I assumed that everyone out 
there had been following this group forever and would know what I was talking
about.  *I* have not been following this group forever! 8-)

> *REQUIRING* the P5.1 upgrade, I think you are misinformed (slightly).  The
> ICUS plans for upgrading your 3B1 to accept two hard drives DOES NOT REQUIRE
> the previous installation of the P5.1 upgrade.   I believe the same goes
> for John's forthcoming board, although I could be mistaken.  The P5.1
> FIELD upgrade's jumpers on the motherboard will speed up the installation
> of the upgrades because some of the jumpers, as well as, the socket that
> needs to be installed on the motherboard will already be there.   

John's board will plug into the socket provided by the P5.1 upgrade and
REPLACE the PAL used in the P5.1.  

I have actually had inquiries from people who want the P5.1 but do not
plan on adding a second hard disk but they have a monster full height
drive waiting now.  How they are going to backup a 15 head drive without
being able to mount a second hard disk does conjure up masochistic 
thoughts though doesn't it?

> I believe John is using another type of PAL (obviously with different
> PAL equations) for his upgrade, so the PAL will be a wasted part (and
> probably the hardest part to get to do the P5.1 upgrade, since most
> people don't have PAL programmers handy).

Yes, and yes.  The 9 jumpers and socket for the PAL are still needed,
aren't they, John?

> Both upgrades (ICUS and John's) will have the functionality that the
> P5.1 FIELD upgrade gives, namely the additional head select line (for
> hard drives >8 heads).
> 
> Hope this clarifies things a bit...
> -Lenny

Yes, it does clarify things a bit.  As the summary line says, I probably
should not post articles in the wee hours of the morning.  What was obvious
to me at 2 AM does look different at 2 in the afternoon if you cannot read
my mind (a feat that even I have a hard time with :-)).

Jan Isley, follower of Zen, picker of nit
jan at bagend | gatech!bagend!jan | (404) 434-1335