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From: djh9381@ultb.isc.rit.edu (D.J. Halko)
Newsgroups: comp.sys.tandy
Subject: Re: Tandy TL/2, memory upgrade?
Message-ID: <2431@ultb.isc.rit.edu>
Date: 14 Mar 90 01:47:31 GMT
References: <2831@uwm.edu> <90071.005749JAP131@psuvm.psu.edu>
Reply-To: djh9381@ultb.isc.rit.edu (D.J. Halko)
Organization: Information Systems and Computing @ RIT, Rochester, New York
Lines: 45

> I have a 20 meg IDE drive, can I put a hard card into it also?

People say that the power supply isn't big enough to handle it... well folks,
I was running my 40 Meg st251 (I think it was a 251 now... been a long time
now) with a power supply that delivered 1 amp at 12 V and 1 at 5 V... it heated
it up alot, but as long as it was heat-sinked down, there was no problem
(I never shut the machine down either... always stayed running...)

Now, you have to remember, the largest draw from that hard drive is during
startup and during seeks... as long as you don't do 2 simultaneous seeks
with both hard drives, you won't be straining anything. 

A fine example of this is my current hard drive now. I have a Priam 519
running 191.2 Megabytes... the power consumption at startup is 64 Watts 
(peak startup) and 57 Watts (peak seeking) with an average consumption
of 35 Watts and an idle of 29 Watts. In other words, an idle hard drive
(just spinning) will draw about 1/2 as much as 1 drive spinning up or
seeking... 2 drives in idle pull as much as 1 starting up. If the 
power supplies were designed right in the TL/2, it should give MORE than
required for 1 hard drive spining up/seeking, which means with one drive
idle at any one time, you should not be having any problem. 

Now, since you are probably running MSDos on the TL/2, you should not have
a problem with 2 drives seeking simultaneously often. With a slight strain
of something like that happening occasionally, you will not do any damage.
The power supplies are made with a good margin of "beat-on-ability" since
they have no idea how many cards you will be popping in there. With 5 slots
(I think it is 5 slots, eh? I forget sometimes...) there should be adequate
power... I have seen 2 drives run in several 1000's before.  The IDE drive
should take even less power since you don't have a separate controller card.
Your hard cards are miniscribes (if not, just 3 1/2" hard disks) and you
can run those off of batteries... they don't really pull alot...

Now my system, I have to worry about simultaneous seeking on drives all
the time (running OS9 with 191.2 Meg drives and DMA floppies and other
DMA hard drives simultaneously, there are always simultaneous seeks going
on.... I have to be a little more careful... but then again, there is another
OS9 system running in Rochester that was running a 191.2 Meg, 150 Meg, and
2 80 track drives on a 65 Watt power supply with lots of simultaneous seeks
for about 1 year... never any problems... he was running a BBS!

You would be suprised how well that equipment is built that you buy at Shack.

djh9381@ritvax.bitnet
David J. Halko