Another PDP-11 available: Wisconsin

From: Jerome Fine <jhfine_at_idirect.com>
Date: Wed Oct 11 19:29:19 2000

>ajp166 wrote:

> It can but... Try doing a hardware hack using a DRV11 card with
> a static ram hooked to it as a ram disk. You can emulate up to
> a point and then it stops.

Jerome Fine replies:

I agree that if the emulator does not handle all hardware interfaces -
and none do all - then what you refer to can't be done. But since
the emulator allows a RAM: disk of any size (I have used up to
64 MBytes on a 96 MByte system), I don't need the limited
"ram disk" you use on the real PDP-11 hardware. Again, I am not
knocking the real PDP-11 hardware for those who feel that way,
I just don't find it very exiting running real PDP-11 hardware as
opposed to using the emulator when it is appropriate.

Now when I can't run the emulator on a newer PC any more and the real
PDP-11 hardware is still working and the old PC is broken, then back
to the tried and true. It will be a race between 3 things:

(a) The real PDP-11 hardware broken

(b) The emulator not able to run on a new PC OS and the old PC broken

(c) Me broken (dead!)

I figure the race to last between 10 and 40 years. Right now I am 62 years
old and have been using the PDP-11 for over 25 years. My minimum goal
is at least 50 years!! I would like to last until January 1st, 2036 when the
DATE value in RT-11 first becomes negative. Talk about long range goals
when this list is supposed to look back only 10 years.

> >and this is a VERY BIG PLUS - I had occasion to attempt
> >to debug (or at least understand) the boot code for a stand alone
> >program. Try stepping through the boot block of an RX02 on
> >a real PDP-11. With the emulator and even rudimentary
> I've done it, ODT. Emulators help some here, then again if the
> boot block is on a real RX02 (in DD mode) or an RL02. Your
> cooked again and must have real hardware.

Yes, I could have gone to the trouble of putting ODT into memory along
with the boot ROM code for that DD RX02 on the real PDP-11, but
it was much easier to copy the RX02 image to an RX50, then copy
the RX50 image from the HD floppy drive to a container file on the
Pentium which was then MOUNTed as an RX02 image. The emulator
allowed me to stop after the code at boot block zero was loaded and
then step through the code. Interestingly enough, the stand alone program
contained a copy of software ODT which I then used to continue the
debugging (after it was loaded by the boot program in block zero).
Since the emulator was able to emulate a real RX02 drive in double
density mode (pretend the container file of 988 blocks was an RX02
image on an 8" RX02 DD compatible floppy), there was no problem
at all with the emulator. And it was all quite legal since no operating
system was involved (although the RX02 image had been prepared
under RSX-11 for which I don't have a license).

The real trouble is that I think you are correct for being very inclined
to be real PDP-11 hardware oriented. But do you feel it is OK for
me to be very inclined toward software? If your answer is YES!,
then we both agree completely. BUT, I will still continue to agree
that real PDP-11 hardware is great for those who are inclined that
way!!

Sincerely yours,

Jerome Fine
Received on Wed Oct 11 2000 - 19:29:19 BST