[Simh] XXDP v2

Wed Dec 30 14:49:42 EST 2015

2015-12-30 18:57 GMT+01:00 Bob Supnik <bob at supnik.org>:

> It's the MMU.
>
> After adding the BEVENT disable logic, I noticed that the MMU option
> cannot be disabled in any model, although it was in fact optional in the
> KDF11A module (but not the 11/23 system). So I hacked the configuration
> table to make the MMU optional and tried an 11/23 with no MMU. It hangs
> just like the 11/03, 04, 05, and 20.
>

Great that we have a solution for BEVENT!

According to the manual XXDP shall resort to the small monitor if the MMU
is non present or faulty. (page 2-2 indicate so as far as I read it)

I tested the images at
http://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/xxdp/
I can boot the two XXDP RL02 images attached to rl0 on 11/04, 11/05 and
11/20.

PDP-11 simulator V4.0-0 Beta        git commit id: ea4d9a16
sim> set 11/04
Disabling XQ
sim> attach rl0 ./xxdp22.rl02.img
sim> b rl0

CHMDLD0 XXDP+ DL MONITOR
BOOTED VIA UNIT 0
28K UNIBUS SYSTEM

ENTER DATE (DD-MMM-YY):
Simulation stopped, PC: 150574 (BPL 150652)
sim> attach rl0 ./xxdp25.rl02.img
sim> b rl0

CPU NOT SUPPORTED BY XXDP-XM

BOOTING UP XXDP-SM SMALL MONITOR

XXDP-SM SMALL MONITOR - XXDP V2.4
REVISION: D0
BOOTED FROM DL0
28KW OF MEMORY
UNIBUS SYSTEM

RESTART ADDRESS: 152010
TYPE "H" FOR HELP

.
Simulation stopped, PC: 151006 (TST R0)
sim> set 11/05
sim> b rl0

CPU NOT SUPPORTED BY XXDP-XM

BOOTING UP XXDP-SM SMALL MONITOR

XXDP-SM SMALL MONITOR - XXDP V2.4
REVISION: D0
BOOTED FROM DL0
28KW OF MEMORY
UNIBUS SYSTEM

RESTART ADDRESS: 152010
TYPE "H" FOR HELP

.
Simulation stopped, PC: 151002 (JSR PC,150664)
sim> set 11/20
sim> b rl0

CPU NOT SUPPORTED BY XXDP-XM

BOOTING UP XXDP-SM SMALL MONITOR

XXDP-SM SMALL MONITOR - XXDP V2.4
REVISION: D0
BOOTED FROM DL0
28KW OF MEMORY
UNIBUS SYSTEM

RESTART ADDRESS: 152010
TYPE "H" FOR HELP

.
Simulation stopped, PC: 150674 (BPL 150750)

So it cannot be the MMU (not alone at least). It has to be a combination
with device driver.

>
> Why it fails is unknown. Mattis' real 11/04 gets further than the
> simulator, although it ultimately fails.
>

I am not sure if this is a co-incidence but the real 11/03 behaves very
similar to the emulated 11/04 in that sense that the address it stops at
when halted are very similar. The emulated 11/04 seems to be in some kind
of loop testing for console input.

I did some further testing creating DU-device images (RD51) for XXDP+, XXDP
V2.5 (2.4?) from the RL02-images mentioned above. They both boot on a 11/04
(and all the others) in SimH.

https://dl.dropboxusercontent.com/u/96935524/xxdp-plus-du.dsk.gz
https://dl.dropboxusercontent.com/u/96935524/xxdp-v25-du.dsk.gz

Then I used the V2.2 XXDP image I posted earlier and made a small RD51
image out of it.

https://dl.dropboxusercontent.com/u/96935524/xxdp-v22-du.dsk.gz

In SimH it boots on 11/73 but not the 11/04.

I have not been able to test real systems yet.

I don't think this is such a big issue since SimH can in fact run both
XXDP+ and XXDP V2.5 (V2.6) and the real machine also had problems with XXDP
V2.2. It can also be bugs in XXDP V2.2 that behaves slightly different?

/Mattis

>
> /Bob
>
> On 12/30/2015 12:00 PM, simh-request at trailing-edge.com wrote:
>
>> Message: 1
>> Date: Wed, 30 Dec 2015 11:28:35 -0500
>> From: Bob Supnik <bob at supnik.org>
>> To: "simh at trailing-edge.com" <simh at trailing-edge.com>
>> Subject: Re: [Simh] XXDP v2
>> Message-ID: <56840633.5080505 at supnik.org>
>> Content-Type: text/plain; charset=utf-8; format=flowed
>>
>> I did a quick hack and removed the clock from the device list,
>> effectively disabling it. With that done, the 11/23 runs XXDP V2
>> correctly, with 64KB of memory. I'll add BEVENT DISABLE to formalize this.
>>
>> So the failing systems are the 03, 04, 05, and 20. Possible common
>> factors:
>>
>> - no memory management
>> - no EIS
>>
>> I tried an 11/03 with EIS and no clock, and it fails, so EIS does not
>> appear to be the problem.
>>
>> I'm now looking for XXDP monitor sources. The failure happens before
>> anything is printed, but a listing would still be of great help.
>>
>> /Bob
>>
>>
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