Heathkit H27

[Allison]

>
>Subject: Re: Heathkit H27
>   From: "Ethan Dicks" <ethan.dicks at gmail.com>
>   Date: Thu, 07 Sep 2006 12:30:11 +1200
>     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>On 9/7/06, Jay West <jwest at classiccmp.org> wrote:
>> Can the H27 (dual 8" floppy drive) be hooked up to an H8? Or was that
>> strictly an H11-only device?
>
>Dunno about the H8.
>
>> Of for that matter, can an H27 be hooked up to a non-heath Micro PDP11?

Yes, if you have the heath interface card as well.  If memory serves 
the standard RT-11 DX.sys was compatable.

>
>My recollection of debugging some H27 issues a couple of years back is
>that there's a boot prom on the Qbus card for the H27.  If that's the
>case, then as long as it isn't stomping on a bootstrap ROM somewhere
>else on the bus, then you should have no problems.  Heath's card should
>be register-level compatible with either the RXV11 or the RXV21 (can't
>remember which one right now).

The prom on card can be disabled.  It worked well with 11/2 and KDF-11A 
cpus.

The card is RXV-11 compatable.   The big upside with the H27 is it would 
format 8" (RX01) disks.  The downside is the drives, the spindle clamp
was plastic and would dryout and crack.


>My H-11 came with a KDF-11, DEC memory, pretty much DEC
>everything; just the Heath backplane and PSU and floppy controller.
>The previous owner never booted from floppy, though; he hacked the
>case and added an off-to-the-side CD-interconnect and used an RLV11.

Thats a ugly hack.  Many were upgraded to 11/23 cpu, Q18 ram and some
times DLV11j for more IO with fewer boards.

>It took a bit of work to get it all back together.

I'll bet.  Test the PS well, the LVSMPS was not every reliable.



Allison