WH-27 Problems (was RE: Heathkit H8's, H9's and H-11's)

[Allison]

>
>Subject: Re: WH-27 Problems (was RE: Heathkit H8's, H9's and H-11's)
>   From: "Barry Watzman" <Watzman at neo.rr.com>
>   Date: Thu, 19 Apr 2007 12:54:42 -0400
>     To: <cctech at classiccmp.org>
>
>Re:
>
>From: "Robert Armstrong" <bob at jfcl.com>
>Subject: WH-27 Problems (was RE: Heathkit H8's, H9's and H-11's)
>
>.....
>
>  In extended mode the drive could handle 512K diskettes ... So the bottom
>line is that if you want to run standard RT-11 on the H-11, you have to set
>the switch to RX-01 mode and you have the equivalent of an RX01 drive.  No
>double density ...
>
>*************
>
>I don't think that's correct; the controller in the H-27 (WH-27) is a Z-80
>with a Western Digital 1771.  The 1771 is most definitely single density
>only.  It's not capable of double density.

Barry is correct. I know the beastie well enough and single density was 
it's thing.  However there was a third party version on the market that 
could do DD (but not DEC RX02) and was modeled like the H27.  

there wer others in the PDP-11 market that did compatable rx02 DD (two
sided) such as the DSD880 and a few others.

Allison