[c-nsp] 1600R series router internals

[Tom Storey]

Hi Alexander,

Yep, had come across uClinux, but Im going to a lower level than they did I
think. And by the time I looked at their documentation I had pretty much
already worked out everything they had.

Im much more of a "bare metal" kind of person I guess (I do a lot of
hobby work with microcontrollers). So for my projects I took out the
factory boot ROMs and flash and started from the ground up - locate and
document internal registers, address map, etc - basically working out how
to bend them to my will.

Theres a pretty big "retro scene" these days around old computer hardware
and processors, and I figure with 680x0 processors on-board and a bunch of
other components (like ethernet controllers!), these old routers could
maybe see some new life. :-)

Ive put everything I know up on github with some example code:

https://github.com/tomstorey/c2500re
https://github.com/tomstorey/c1600re

As projects they are still somewhat "works in progress", but the code
examples do compile and boot with appropriate mods.

On Fri, 26 Mar 2021 at 13:30, Alexander Huemer <alexander.huemer at xx.vu>
wrote:

> A long time ago somebody attempted a port of Linux to the Cisco 2500
> platform already. Not sure if you stumbled upon this already during
> research.
> Please share your achievements, this is interesting.
>
> -Alex
>
> [1] http://www.kdvelectronics.eu/uClinux-cisco2500/uClinux-cisco2500.html
>
> On Thu, Mar 25, 2021 at 05:23:31PM +0000, Tom Storey wrote:
> > Hi all, this is probably a long shot from far out of left field, but I
> > wonder if anyone is familiar with the deep inner workings of the 1600R
> > series routers?
> >
> > Long story short, I got a bit bored recently with all of the coronavirus
> > related restrictions, and started to reverse engineer some older model
> > Cisco routers (2500 and 1600R) that are based on Motorola 68000 family
> > CPUs, with a "no particular reason" goal of making FreeRTOS run on them
> > (achievement unlocked.)
> >
> > But the 1600R is throwing me a curve ball, and Im having difficulty
> > seemingly "unlocking" access to the memory ranges that cover the WIC slot
> > and the PCMCIA controller registers.
> >
> > Ive used Ghidra to disassemble and rummage through the factory boot ROM
> > code to figure out basically "what Cisco did", and re-implemented it
> > myself, but I still seem to be missing something. Basically, I wondered
> if
> > someone here might be familiar enough with these old boxes at a low
> enough
> > level and might know if there is something in particular that needs to be
> > poked to make this work?
> >
> > Thanks in advance!
> >
> > Tom
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