contemplating selling my Canon Cat

Tony Duell ard at
Thu Jan 10 15:43:29 CST 2008

> >> All of the I/O, Floppy, video, modem and such, are through custom
> >> Canon chips. I'm told that they emulate standard chips because
> >> they originally built the prototypes with standard off the shelf parts.
> >
> > Ouch!. Before I read that, the Cat was high uop on my (mental) list of
> > desirable machines. Now it's at the bottom :-(.
> >
> > How much is known about these ICs? Software interface (registers, etc)?
> > Pinouts?

>  The fail rate on these parts is quite low. I know a fellow in Oregon
> that uses around 6 of these daily in his business. The only fails he's

Err, yes, but it still makes the machine a lot less interesting for a 
hardware hacker like me. 

> had is one CRT and several disk drives. He has been using them
> for years!
>  The disk drive is hard to find. They have a 20 pin ribbon cable intead
> of the more standard cable connector. This cable supplies the power as well.

Is it standard signals and data rates? If so, presuamly an adaptor could 
be wired up.

>  Like I said, these do emulate standard off the shelf parts, it
> is just that I've not dug into the code enough to see what
> might be the particular part used. I've seen the low level disk code
> and it look familiar. I think it is 765 but don't quoke me on that.
> The display is a question. I know there are several value in the init
> routine that are sent to it but I have no idea what it might be.
>  The video is bit mapped in RAM so doing graphics is easy enough.
>  Anyway, the price is most likely higher than what you might expect.
> The last one on ebay went for around $800. Unless your just lucky

YEs, I realise they're not exactly cheap, and finding one in the UK is 
almost impossible (this is not the sort of thing I'd risk having shipped. 
I've seen what shipping companies can do to well-packed HP (== built like 
a brick outhouse) machines.

Now while I _would_ consider spending that sort of money on a classic 
computer, I'd not now sped it on a Cat. The reason is that I couldn't 
maintain the Cat, due to all that custom silicon. And if one of those 
chips failes, I've essentially lost my money. Whereas if a TTL chip fails 
in an old minicomputer, I can probanly get the machine goign again. The 
chip in questiuon may well have not been made for many years, but there 
are likely to still be soem around and if not, I can get data and kludge 
up a substitute. This doesn't apply to the Cat's custom chips.


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