# Re: modeling a simple cpu **URL:** \ **Category:** Ruby\ **Created:** [October 26, 2006, 10:28pm UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764 "2006-10-26T22:28:48Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 26, 2006, 10:28pm UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/1 "2006-10-26T22:28:48Z")
From: Ara.T.Howard [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] > 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? šŸ™‚ ---
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 26, 2006, 10:34pm UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/2 "2006-10-26T22:34:49Z")
On 10/26/06, Gavin K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > From: Ara.T.Howard [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] > > > 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? šŸ™‚ Right, why should we help him hey? Seriously Ara wasnā€™t there a Ruby Q. about it [http://rubyquiz.com/quiz88.html](http://rubyquiz.com/quiz88.html) (the only one I replied to BTW)? HTH Robert ā€“ The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. - George Bernard Shaw ---
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 26, 2006, 10:36pm UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/3 "2006-10-26T22:36:49Z")
On Oct 26, 2006, at 3:28 PM, Gavin K. wrote: > From: Ara.T.Howard [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] > > > 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? šŸ™‚ I agree. šŸ˜‰ James Edward G. II ---
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 26, 2006, 10:50pm UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/4 "2006-10-26T22:50:51Z")
Gavin K. wrote: > From: Ara.T.Howard [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] > > > 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? šŸ™‚ 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 doesnā€™t support interrupts or threads, otherwise there is little chance to mimic its behavior. ---
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 27, 2006, 12:35am UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/5 "2006-10-27T00:35:06Z")
On Fri, 27 Oct 2006, Paul L. wrote: > 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 doesnā€™t support > interrupts or threads, otherwise there is little chance to mimic its > behavior. itā€™s for these guys [http://heasarc.nasa.gov/docs/heasarc/missions/dmsp.html](http://heasarc.nasa.gov/docs/heasarc/missions/dmsp.html) [http://www.ngdc.noaa.gov/dmsp/](http://www.ngdc.noaa.gov/dmsp/) at this point i only need to model a limited subset of the processor (i donā€™t know the type yet). basically iā€™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 itā€™s ultra simple - basically iā€™ll just have to model rom, ram, registes, and ops. hey - a smell a ruby quiz! šŸ˜‰ -a ---
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 27, 2006, 12:27am UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/6 "2006-10-27T00:27:05Z")
On Fri, 27 Oct 2006, Robert D. wrote: > Right, why should we help him hey? > Seriously Ara wasnā€™t there a Ruby Q. about it > [Ruby Quiz - Chip-8 (#88)](http://rubyquiz.com/quiz88.html) > (the only one I replied to BTW)? > > HTH > Robert great resource! thanks! -a ---
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 27, 2006, 1:01am UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/7 "2006-10-27T01:01:10Z")
removed\_email\_address@domain.invalid wrote: > > > Not to distract the thread from your very real question, but you do > > > behavior. > > ``` > ! > ! > > ``` > > simple - > basically iā€™ll just have to model rom, ram, registes, and ops. > > hey - a smell a ruby quiz! šŸ˜‰ > > -a Isnā€™t there an open-source ā€œuniversal old architecture emulatorā€ package of some kind? I remember seeing it in Debian when I was running Debian ā€“ it could play most of the old Atari games, etc. I can certainly see if itā€™s in Gentoo, if I can figure out what it was called. ---
**Author:** ![phrogz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/2acd7d/32.png) [@phrogz](https://www.ruby-forum.com/u/phrogz)\ **Post date:** [October 27, 2006, 1:25am UTC](https://www.ruby-forum.com/t/re-modeling-a-simple-cpu/73764/8 "2006-10-27T01:25:12Z")
M. Edward (Ed) Borasky wrote: > Isnā€™t there an open-source ā€œuniversal old architecture emulatorā€ package > of some kind? I remember seeing it in Debian when I was running Debian > ā€“ it could play most of the old Atari games, etc. > > I can certainly see if itā€™s in Gentoo, if I can figure out what it was > called. I think I found it ā€¦ simh [http://simh.trailing-edge.com/](http://simh.trailing-edge.com/) Of course, Iā€™m probably the only one on this list thatā€™s actually _touched_ some of those gizmos šŸ™‚ Sheesh ā€“ a computer museum on your hard drive šŸ™‚