[vcf-midatlantic] early Cisco routers, was Re: WTB: Cisco IGS

Dave McGuire mcguire at neurotica.com
Thu Feb 8 22:42:02 EST 2018

On 02/08/2018 09:51 PM, Kenneth Seefried via vcf-midatlantic wrote:
>> Anyone have an old IGS kicking around? I've been working on my
>> DEChub 90T1 and would like to see just how similar the two are.
> I have at least one (I learned IOS on it), but have no idea where I stored
> it or when I'll have time to find it.  I'll keep you in mind.
> Yes, the IGS was a 68k-based, fixed-port (1 AUI ethernet and 1 sync serial)
> router.  It was contemporary with the high-end AGS and midrage CGS.  Ran
> IOS out of ROM, and upgrading required a physical ROM swap.  Mine was IOS
> 8, but I think there was an IOS 9 update before the IGS was replaced by the
> c2500 series.

  There were distributions of IOS 10, and possibly 11, for the IGS.  I
don't know if they were commercially available, but we had it at Digex.
I have EPROM and flash images for 10 for the IGS/MGS/etc routers here

  There was only one version of the IGS that stored its IOS image in
flash, the token ring version.  That was closer to being a 3000 than an
IGS, but it was badged "IGS".

  The 3000 was an IGS with a 20MHz 68030 replacing the 16MHz 68020, and
flash instead of EPROM for IOS.  And the chassis paint and stickers were
the later colors, and had the updated logo.

  The 2500 series was a technology refresh, shrink, and repackaging of
the 3000, but the systems-level architecture remained largely the same.
So close, in fact, that early IOS releases were the same (actually the
same image files) between them.

  All of these are "integrated interfaces" versions of the modular CGS
("Compact"), MGS ("Medium"), and AGS ("Advanced") routers.  Essentially
small, medium, and large.  These were all Multibus-based, but the AGS+
added the Cbus interconnect, which required a separate board, a Cbus
controller to bridge it to the Multibus.  I was told by a Cisco guy at
the time that Cbus was an implementation of the NuBus protocol, but that
may not have been correct.  Cbus is about four times faster than
Multibus.  The Cbus slots go alongside the Multbus P1 connectors, where
the card-edge P2 connectors would normally go, but used (I think) DIN
41612 connectors instead of card-edge.

  The CGS/MGS/AGS/AGS+ routers could be 68030- or 68040-based, depending
on whether you populated it with a CSC/3 or CSC/4 CPU board.

  Great machines, all of them.  And great memories too.


Dave McGuire, AK4HZ
New Kensington, PA

More information about the vcf-midatlantic mailing list