Oki 3305 disk drives

Wouter de Waal wrm at dW.co.za
Wed Mar 15 04:15:33 CDT 2017

Hi all

OK, following up on my own post here.

>I have a couple of Oki 3305BU 1/3 height 5 1/4" drives.
>On startup the motor spins and the heads load, but the heads don't
>move. Also, my BIOS tells me I have a drive failure.
>On taking them apart for a bit of a lube I noticed they have EPROM
>8748s inside. Could this be the problem, EPROMs lost data? This would
>be a first for me, I have EPROMs from the seventies which are still fine.

I caused (I have people working for me who are really good at this) 
the 8748 to be removed from the one PCB. Reading it in my Expro gives 
me sort-of random results. Looks like some bits are high, some are 
low, and some float all over the place. No two reads return the same 
data, but some bytes are constant over two or three reads and other 
bytes are constant over two or three other reads.

Is this the way an EPROM would fail? Seems reasonable to me.

Anyway, I guess I'm SOL unless I can find a working drive. As far as 
I can tell these were used in the Heath / Zenith 170/170 luggables, 
also in the Morrow Pivot maybe.

Tony would probably just rewrite the firmware. It's only 1024 bytes, 
how hard can it be? :-) Seriously, I am thinking of reading each byte 
say 100 times, averaging that, and then sticking the whole thing 
through a disassembler. But it seems a bit of a mammoth task.


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