From: "M. Edward (Ed) Borasky" <znmeb@...>
Date: 2006-10-27T08:00:57+09:00
Subject: Re: modeling a simple cpu

ara.t.howard@noaa.gov wrote:
> On Fri, 27 Oct 2006, Paul Lutus wrote:
> 
>> Gavin Kistner wrote:
>>
>>> From: Ara.T.Howard [mailto:ara.t.howard@noaa.gov]
>>>> i need to model the on board cpu of a satellite in order to
>>>> mock running uploaded commands.  basically i need to model
>>>> the internal state and all incoming commands so i can
>>>> determine register states at a given point in time.
>>>
>>> Not to distract the thread from your very real question, but you do
>>> realize that you have one of the coolest jobs around, right? :)
>>
>> The last processor I successfully modeled was the old 6502 (Apple II),
>> since
>> then processor behavior has become too difficult to sort out in any
>> reliable way (IMHO).
>>
>> It would be interesting for the OP to reveal what kind of processor is
>> involved, and how complex. I am going to assume it doesn't support
>> interrupts or threads, otherwise there is little chance to mimic its
>> behavior.
> 
> 
> it's for these guys
> 
>   http://heasarc.nasa.gov/docs/heasarc/missions/dmsp.html
>   http://www.ngdc.noaa.gov/dmsp/
> 
> at this point i only need to model a limited subset of the processor (i
> don't
> know the type yet).  basically i'll be executing something long these lines
> 
> 
>     !=================================================================
>     !*****  GAIN ORBIT MEMORY FOR OPS45  26 JAN 04 - 01 FEB 04   *****
>     !=================================================================
>     !
>      0.000  CMD  OAXSPG   0x00       ; 807E#  (PAGE=0)
>      0.000  CMD  OGNASG   LIN        ; 0010#  ASGC LIN
>     !
>      0.076  CMD  OAXLOD   0xA2       ; 511E#  (112dB) (SED)
>      0.076  CMD  OAXSTR   0x44       ; A22E#  (BC MAX)
>     !
>      0.316  CMD  OAXLOD   0x03       ; 819E#  (.08) (VED-1/00)
>      0.316  CMD  OAXSTR   0x48       ; A42E#  (BRDF X2)
>     !
>      0.324  CMD  OAXLOD   0x06       ; 831E#  (.25) (VED-00/12)
>      0.324  CMD  OAXSTR   0x46       ; 232E#  (BRDF HRD)
>      0.324  CMD  OAXLOD   0x9E       ; 4F1E#  (136dB)
>      0.324  CMD  OAXSTR   0x44       ; A22E#  (BC MAX)
>     !
>      0.326  CMD  OAXLOD   0x8E       ; C71E#  (118dB) (VES)
>      0.326  CMD  OAXSTR   0x44       ; A22E#  (BC MAX)
>     !
>      0.650  CMD  OAXLOD   0x29       ; 149E#  (.02)
>      0.650  CMD  OAXSTR   0x48       ; A42E#  (BRDF X2)
> 
>     ....
>     ....
>     ....
> 
> as you can tell these are load/store/add instuctions.  there are no
> parameters, all the values are burned on board before flight - so there are
> only certain values you can do ops with.  as you can tell it's ultra
> simple -
> basically i'll just have to model rom, ram, registes, and ops.
> 
> 
> hey - a smell a ruby quiz!  ;-)
> 
> 
> -a

Isn't there an open-source "universal old architecture emulator" package
of some kind? I remember seeing it in Debian when I was running Debian
-- it could play most of the old Atari games, etc.

I can certainly see if it's in Gentoo, if I can figure out what it was
called.