[Coco] Coco1 and IDE HD power

[Gene Heskett]

On Monday 02 October 2017 08:35:04 Rietveld Rietveld wrote:

> Just curious. Why does the drive need both 5 and 12v.   And I assume
> that the computer power supply converts from ac to DC? I thought it
> would be ac only?
>
> Sent from my BlackBerry Passport Red Edition.
>   Original Message
> From: Francis Swygert
> Sent: Monday, October 2, 2017 6:37 AM
> To: coco at maltedmedia.com
> Reply To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] Coco1 and IDE HD power
>
>
> You may need two wall wart, a +5V DC (about 0.5A -- 500mA) and a +12V
> (at least 1A -- 1000mA). Just make sure they have DC output, not AC.
> Will say in the text on the wall wart.  Frank Swygert Fix-It-Frank
> Handyman Service
>  803-604-6548

Back in the day of IDE drives, the logic needed 5 volts, often an amp or 
more, and the disk motors needed 12 volts, sometimes 2+ amps for the 
first 2 or so seconds at spinup time.  Half an amp or less once spun up.
Some of the reductions in current draw are the reduced number of heads 
that come with higher recording density medium, and of course the 
reduced number of disks on the spindle to be spun up, and the 
autoparking off the disk of the heads made possible by the upside down 
aerodynamic head profiles, so the head can be several thousandhs off the 
disk at rest, and as the disk spins up, the air flow drives them closer 
to the disk until they are balanced at flying height above the surface 
of the disk.  All of which contribute to less power draw to spin the 
disk.

I have, currently spinning, 2 of the ultra thin 1TB Seagate 2.5" drives 
that are being powered by the 5 volts at under half an amp available 
from a usb-2 port on a raspberry pi 3b in one case, and from a rock64's 
usb-3 port in the other case. Neither disk is developing more than a 5F 
temp rise anyplace on its case.  With that lack of heat, I expect to 
have good life from both, at a cost of nominally $50 each from Wallies 
today.

The "commodity" drives seem to be getting more dependable. The oldest 
drive of the 3 in this machine, all 1 terabyte 3.5" Sata-II drives, had 
25 reallocated sectors when I first installed smartctl several years 
ago, had 20,000 spinning hours then, just a month ago still had only 25 
reallocated sectors, and will soon have 68,000 spinning hours accrued.  
But I am going to have to replace it before too long, or reduce the 
number of virtual tapes on it as amanda (a backup program for *nix's) 
has it at 85% of capacity now.

7.5 years is pretty good for a drive I paid about $140 for that far back 
up the logs. :)  And $50 a terabyte today.  Our toys are getting 
cheaper, and in some cases, more dependable.

I am convinced also that my habit, when I put a new drive into this 
machine, I go to the makers site and download a cd image that has the 
latest firmware for that drive in an auto-install format, all I have to 
do is put the burnt image into a dvd-rw and reboot to it, the software 
scans the machine and if the drive it finds needs its firmware updated, 
it does it. One of those early 1TB drives was slow, 20 megs a second.  
The firmware update brought it up to 120 megs/second.

Highly recommended by Grandpa Gene.

Also, a prayer or hundred, for those at the concert in Lost Wages last 
night. This guy has handily broken John W. Hardin's record. They need 
our prayers, and in way too many cases, those 7 Spanish Angels to do the 
carrying home.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>