Booting real RT11 on a Heath H-11

From: Robert Armstrong <bob_at_jfcl.com>
Date: Sun Jul 25 22:24:06 2004

  I've made some progress on this topic since my original post and the
short answer is yes, you can run RT-11 on the H11.

  The WH-27 drives have some enhancements over real RX02s - in
particular, the WH-27s can format diskettes (!!!) - and there's a switch
on the front of the WH-27 for "Enhanced Mode" or "RX-01" mode.

  HT-11 (the Heath crippled version of RT-11) will only boot if the
switch is set to "extended" (if you try to boot with it set to "RX-01",
HT-11 tells you to change the switch and reboot!). I think Ethan asked
how Heath/Digital prevented users from running HT-11 on a real PDP-11;
I'd assume this is the way.

  If you set the switch to "RX-01" then you can boot real RT-11 (at
least V4 and V5 - I've tried both) _provided_ that your diskette is a
RX01. "RX-01" mode really means RX01, not RX02. But if you have a
bootable single density RX01 floppy with the system handler set to the
DX device, it will boot. My only mistake was that I was trying to boot
RX02 media.

  This is doubly annoying because the WH-27 is double density capable,
but only in "extended" mode. In fact, you can boot HT-11 (again, in
"extended" mode) and do a directory listing of a double density RT-11
RX02 diskette, but you can't boot it in "RX-01" mode.

  Of course, the LSI-11/2 has no memory management so you can't run the
XM monitor, but that's to be expected.

  Actually, I want to do something similar to Ethan's old boss, except
that I plan to add a hard disk by using a Dilog DI-602 card. It
attaches to a standard MFM disk and emulates a RL02 controller and, best
of all, it's only a double module. It'll fit the backplane easily.

  The only problem is that the boot ROMs, which are on the WH-27 card,
don't know how to boot a RL02. Any ideas?

Bob

-----Original Message-----
From: ed sharpe [mailto:esharpe_at_uswest.net]
Sent: Sunday, July 25, 2004 5:38 PM
To: bob_at_jfcl.com; General Discussion: On-Topic Posts Only
Subject: Re: Booting real RT11 on a Heath H-11


we will be watching this thread but please CC us on any discussing on
this as we will soon be firing up our H 11... and yea it has the heath
drives... I thought I saw some copies of rt 11 that were in the boxes
that did not look heathkit specific but do not know if the guy ever got
them running.

ed sharpe archivist for smecc
----- Original Message -----
From: "Robert Armstrong" <bob_at_jfcl.com>
To: <cctalk_at_classiccmp.org>
Sent: Thursday, July 22, 2004 10:24 PM
Subject: Booting real RT11 on a Heath H-11


>
> I have a Heath H11A (LSI-11/2 CPU!) with the Heath WH-27 floppy
> diskette drives. It boots and runs HT11 (Heath's crippled version of
> RT11) just fine, but when I try to boot a real RT-11 v5 RX01 diskette
> it just halts. I thought that the WH-27 was RX01 compatible. Am I
> wrong, or is there some trick that Heath put in (maybe in the WH-27
> boot ROMs?) to keep it from working?
>
> Thanks much,
> Bob Armstrong
>
>
>
Received on Sun Jul 25 2004 - 22:24:06 BST