You've lost me, Allison. How did you "try it out?" There's a bit that has
to be set in one of the registers to make the drive use and 8-bit interface
rather than the usual 16. No amount of fiddling with the drive will change
that. It either does it or it doesn't, and I've sent email to several
makers of IDE drives, referring to the standard and asking how their drives
handled that paragraph in the standard. Of course you'd have to look up the
standard that prevailed at the time the drives were made.
Please see comments below.
Dick
----- Original Message -----
From: allisonp <allisonp_at_world.std.com>
To: <classiccmp_at_classiccmp.org>
Sent: Sunday, April 16, 2000 5:17 PM
Subject: Re: 8-bit IDE
> >As it happens, the committee did standardize on the one mode bit that
makes
> >the interface an 8-bitter. How extensively that was adhered to remains
to
> >be seen, I guess.
>
>
> Well wishful thinking had me check it out using several 85-130mb drives
> (quantum, Seagate, maxtor, WD) and none seem to do that. After all
> having that would make the interface a no brainer and save a simple silo
> for splitting read and writes. However, it was wishful thinking.
>
What???
>
> As to doing it on S100, been there done that. the interface logic needed
> to do the bus does 3/4s of the work and it only needs a bit more the
> close the loop. CPLD/FPGA/PAL could cover most of that but for S100
> I like real TTL (244/241/373) like parts and NO cmos where the bis
> interface occurs.
>
I personally like the CMOS much better since it drives harder, and since it
pulls and pushes with the same impedance, unlike TTL which sinks 16 and
sources 1.6 mA. I've tried replacing all the bus interface buffers on my
old S-100 cards with AC logic. In some cases I used HC or AHCT (SAMSUNG)
always finding that it all works better than TTL or at least makes prettier
waveforms on the bus. My S-100's are normally DC terminated with simple
220/330 resistor dividers. In a couple of cases I have a passive
termination board with a 3-volt regulator on board, while in another case I
have an active terminator.
>
> Allison
>
>
Received on Sun Apr 16 2000 - 23:40:31 BST