Altair 8800b + drive alignment

From: W. Tom Sanderson <>
Date: Thu Feb 12 18:47:40 1998

I also need alignment for a drive on my 8800b. I have the documentation and procedures plus the MITS program to step to a specific track. In addition to an oscilloscope, one tool needed for alignment is a hammer! The biggest problem will be finding an alignment diskette. The Pertec drives are 32-hard-sectored eight-inch. Most eight-inch drives are soft-sectored. Assuming your drives are one drive per case, they are probably a FD410 with a DC motor. If your drives are two drives per case, they are probably FD511s with a AC motor. Both drives can read the same diskettes. I also have a supply of blank diskettes.

I would appreciate any suggestions on locating an alignment diskette. I would also like to hear from anyone with working drives. I would like backup and add to my MITS software collection.

Tom Sanderson Virtual Altair Museum

To: "Discussion re-collecting of classic computers" <
Subject: Altair 8800b + drive alignment
From: "Andrew Davie" <
Date: Thu, 5 Feb 1998 00:13:10 +1100

I recently purchased an Altair 8800b from the original owner. He told me
that last he used it (1984?), he was having trouble reading from the disk
drive, and he was sure that it needed alignment. Apparently an alignment
disk is required.
I suspect an oscilloscope as well.

I have two questions;

1) Can someone explain the process of aligning a disk drive, what is out of
whack, and how tricky it is for a rank electronics amateur like myself
2) Where can I obtain an alignment disk, if required.

Oh, I forgot to mention, the drive is an 8", the Altair model that has the
same basic case and look of the Altair itself. This repair is one of the (I
suspect) many that will be required to bring the Altair back to life.

I've managed to get it (almost) firing up during the self-test stage, but
one of the address lines doesn't behave (the light doesn't come on on A2
when I flick the switch that should light all of them, yet the light is
operational at other stages). I'll get to that one later.

Looks like a long, slow process. But worth it, no?


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Received on Thu Feb 12 1998 - 18:47:40 GMT

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