Questions - Universe/68, HP-9134A,VT420 composite video

[J. David Bryan]

On 18 Apr 2005 at 11:54, David Comley wrote:

> And that may be the problem. When I had this pointed to the 1631, it
> reported itself as a 9895.

>From "HP's 5 1/4-Inch Winchester Disc Drive Service Documentation" (HP 
09134-90032, August 1983):

  "The 4-Volume configurations cause a 5 Mbyte drive to appear, to the
   host, as a four-unit 9895A flexible disc.  [...]  The controller also
   identifies itself to the host as a 9895A.

  "The Single-Volume configuration is similar to the 4-Volume in that they
   also use the 9895A Amigo protocol. With the Single-Volume, however, a
   drive does not appear to the host to be indentical [sic] to the 9895A."

The four-volume configuration supplies "Identify" bytes 00H/81H (same as 
the 9895A?).  The single-volume configuration supplies "Identify" bytes 
01H/06H.


> Can the option setting be tweaked ? Is it something as simple as a
> jumper setting ?

According to the service manual, there were three controller boards used in 
the 9134A:

 * 09135-69515 for the standard configuration

 * 09135-69501 for option 010

 * 09133-69514 for both standard and option 010 after S/N 2151A04165

Only the last had jumpers for one volume/four volume configuration.  So if 
you had one of the earlier units, you'd apparently need a controller swap 
to effect the change.  For the later unit, there's a "one volume" jumper 
that is installed for option 010, removed for standard.

If your unit is not marked Option 010, then the best bet would be to open 
it up and see which controller is inside to confirm.

                                      -- Dave