H89 CP/M hard-secored boot diskette

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Mon Apr 7 14:03:00 2003

>From: "Patrick Rigney" <patrick_at_evocative.com>
>> Hi All
>> Well, I dug out my H89. I turned it on, POP, turned it
>> off. Smoke comes from the one side.
>> Well, it looked like one of the 2.2 uf tantalums decided
>Oh yeah... that's fully the behavior of the "popcorn" machine I referred to
>> Years ago, I'd place a second drive in the machine by
>> installing two half height drives. The boot drive it
>> behind the other drive so I can't see what the difficulty
>> is with the other disk.
>I just bought a handful of half-height drives and was about to launch into
>this myself. Did you feel a need to upgrade anything in the power supply
>before doing this, or is it up to running both motors simultaneously if/when
>that occurs?

Hi Patrick
 I used it this way for a number of years without any problems.
I do have the drives setup so that the select turns the motors
off when not being accessed. I believe this is the same as the
original. This is a jumper select on most drives.
 I did have to file a little material from the bezel where the
drives fit into the front. Other than that it was reasonable.
You can't see this with the drive installed.
 You do need to make sure that all of the shielding is put back
in. It is close to the yoke of the tube and needs to be protected
from the stray fields( writes will fail ). I don't recall if I
had to drill any more mount holes but I'll know more as I debug
my disk spinning problem. Of course, you need a new cable
( easily made ) and an extra power connector.
 Make sure that only one drive has the terminator( this is often
missed by many ). The controller was originally setup to run
3 drives, one inside and two outside. Dual drives are handy.
Received on Mon Apr 07 2003 - 14:03:00 BST

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