Needed: 1 IBM 8" alignment disk.

From: John B <dylanb_at_sympatico.ca>
Date: Mon Nov 29 20:26:14 1999

-----Original Message-----
From: Al Kossow <aek_at_spies.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Monday, November 29, 1999 10:05 PM
Subject: Re: Needed: 1 IBM 8" alignment disk.


>"I wonder if it really is working most of the way (i.e. it can read ID
>marks and even data) but there's a problem getting that read data to the
>CPU (shift registers, bus drivers, etc)."
>
>Are you trying this on your 8/I or 8/S ?

The PDP-8i.. (it works the same on both units).. This drive has a dual
buffer (50) and was made to be used on some of the slowest computers... The
manual claims from high speed to "DC"... I have it on the 8i as I don't like
to subject the 8/s to questionable hardware.



>
>>From memory, the Sykes interface is REALLY dumb. An 8/S might be too slow
>to handle the data rates..
>

It is... *really* dumb... Its got a 2 sector buffer option(claims it can do
2 things at the same time with the buffers) so I got a bigger really dumb
controller.

It's search algorithm is really funny too:

Read Sector <-------------
If requested Sector <> address then |
If CRC not okay then ---------------------|

(you get the idea.. and infinite loop for most errors)


john


PDP-8 and other rare mini computers

http://www.pdp8.com
Received on Mon Nov 29 1999 - 20:26:14 GMT

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