[Simh] Simh Digest, Vol 117, Issue 4

[Jon Elson]

> Date: Thu, 05 Sep 2013 12:02:04 +0200
> From: Johnny Billquist <bqt at softjar.se>
> To: simh at trailing-edge.com
> Subject: Re: [Simh] single cycle stepping for pdp11
> Message-ID: <5228569C.3060307 at softjar.se>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 2013-09-05 07:15, Mark Pizzolato - Info Comm wrote:
>   
>> On Wednesday, September 04, 2013 at 10:08 PM, Doug Snyder wrote:
>>     
>>> it appears that simh supports single instruction stepping, but not single cycle stepping for the pdp11.
>>>       
>>   
>>
>> Hi Doug,
>>
>> The core behaviors of the simh simulators are built around the execution of instructions.  This is the level which things are simulated at.
>>
>> What problem are you trying to solve or deal with your request to be concerned about clock cycles?
>>     
>
> And even further - single cycle stepping will mean different things on 
> different models of the PDP-11. Or rather, different models do different 
> amounts of work in a single cycle.
>
>   
I worked for years on PDP-11s, and never heard of this single cycle 
stepping.
I can imagine there might be a jumper on one of the boards that enables this
for customer engineer's debugging, but as far as I know you only got single
complete instruction stepping with the halt switch.  I worked with the
11/20, 11/34, 11/45 and even the CalData emulator.

Jon