New (to me) Cat - newbie q's, ROM version, etc...

Skip to first unread message

Jan 29, 2015, 8:20:10 PM1/29/15
Hello All,

I've recently acquired a Cat. After a good cleaning, everything seems to work - the disk, all keys, etc... though I have not tried to print yet. The double centronics cable should arrive tomorrow.

Anyway, I know I have to replace the battery - Are there any other must-do's I should know about when I have it opened up?

Also, I noticed that it is version 1.74 - are there reasons to want the 2.40, etc that I see people discussing on this group? Any easy way to update the ROMs?

Finally, if anyone has an extra machine they would part with, I wouldn't mind having another...



Jan 31, 2015, 11:56:48 AM1/31/15
Be careful taking it apart.
I recommend removing the disk drive, still on the bracket
first. Then remove the monitor on its sled.
Then it will be easier to get the keyboard out of the way.
It is a lot easier then trying to lower the processor board
from the bottom to remove the battery. The keyboard connection
will pull off and you'll need to disassemble it anyway.
I also recommend disassembling the drive and reinforce the
piece of plastic finger holding the rod that guides the head.
I completely replace these on my drive. When they fail, ( and
they will fail )  you'll be tempted to yank the disk out.
 This will destroy the head, making the drive
useless. If the disk gets stuck take the drive apart, remove
the disk and repair the rod mount. It will save the disk drive.
Do note that the cable does not pull off the drive, it is fixed
to the drive. You need to pull the IDC connector from the
mother board.
With the current firmware, if you need to replace the drive,
you need to find one with the DriveReady signal instead of the
DiskChange signal or at least one that can be jumpered. These drive are
This is a possible reason for changing to 2.40. We have source code for
the 2.40.
Another reason is to change a printer driver to work with a printer
you have. With the disk drive problem, you'd need to change the
firmware but it is possible to patch the printer on a disk image
without replacing the firmware.
If you have a Canon printer that matches one of the listed types,
you are fine. The one listed as the "Common" printer is FX80 compatible.
Most all of those are dot matrix printers.
I have made a custom 2.40 with HP pcl5 escape codes. If your printer
needs some other escape codes, you may need to modify the ROM.
it is not that hard to modify the code but recompiling requires
modifications to the machine. You need to increase the RAM
and also add SRAM somehow. IA used a buddy board but I used
some SRAM that I piggy backed on the empty sockets near
the SRAM and Spell checker ROM.
Of course, you can always edit the code and I can compile it for
you, then send it.
If one really wants, one could write a cross compiler and use a
An alternative is to write Forth code to patch the code from the disk
that you load. The code in the machine is designed to allow
patching. I did that initially, before Sandy made the source code
available.  You just have to be careful to make
sure you put the compiled code on each disk you intended to print
from. It self  installs if you put that disk in.
An alternative is to just export to a PC and print from there.
This can also got to a printer but
some of the formatting may be lost. It does require a serial input
to the printer though. I don't recall if it can send rare text to
the parallel without a patch.
I hope this all makes sense.


Date: Thu, 29 Jan 2015 17:20:10 -0800
Subject: [Canon Cat] New (to me) Cat - newbie q's, ROM version, etc...
You received this message because you are subscribed to the Google Groups "Canon Cat" group.
To unsubscribe from this group and stop receiving emails from it, send an email to
To post to this group, send email to
Visit this group at
For more options, visit

David Young

Jan 31, 2015, 12:24:41 PM1/31/15
On Sat, Jan 31, 2015 at 08:56:47AM -0800, dwight wrote:
> Be careful taking it apart.


Is it necessary to remove the monitor and disk drive to reach the

It's been months since I took apart my Cat to replace the battery, but
ISTR turning it upside down and removing the bottom. The motherboard
was attached to the bottom plate. I don't remember if I had to unscrew
the motherboard from the plate or not. According to my hazy memory, the
battery was near one of the corners of the motherboard.

I feel certain that I did not have to remove the monitor. I vaguely
remember unplugging the keyboard.

I know that I took the top off of the Cat at some point, but I thought
that it was an unnecessary step that I took while I hunting for the


David Young Urbana, IL (217) 721-9981


Jan 31, 2015, 12:35:13 PM1/31/15
It is just harder to put the keyboard connector back on.
It can be done from the bottom as you suggest. Mine
is just a recommendation, not a requirement. It is also
a good time to clean dust.
I do consider fixing the drive a requirement.
Virtually, 100% of the Cat drives have the plastic finger
fractured. It is just a time bomb waiting to fail.
One can either replace the finger or glue the end down.
It will fail and when it does, you have to remember,
at that instant, to not yank the disk out of the drive.

> Date: Sat, 31 Jan 2015 11:24:38 -0600
> From:
> To:
> Subject: Re: [Canon Cat] New (to me) Cat - newbie q's, ROM version, etc...


Jan 31, 2015, 5:24:16 PM1/31/15
I thought I'd mention that if you want to soft patch
the printer code, you can see a listing and some instructions
on the DigiBarn Canon Cat page.
Although, specifically for the HP printer, it can be relatively
easy to use it as a basis for any printer. You'll see that it relatively clearly
lays out the typical escape sequences for things like page
length and margins.
It doesn't show how to deal with special print character that are
not ASCII but I can give you that information if you need it.
You will need to know the escape sequences for your particular
Do note, Bruce typed this stuff in from my printed code.
There may be a typo hear or there but I looked at the printer
code that needs to be entered and it look OK. There is one
exception. The editor he used didn't let him type ' without
attaching it to the previous character. It didn't know that in
Forth ' is a word. There are a lot of [' that should be [ '
so watch out. ['] is a word though.
The printer patching code it at the end of the text. There are
a lot of disassembled pieces there that you don't need to
type in.
The strings are counted strings so the first bit is the count.

Sandy Bum

Feb 1, 2015, 11:07:11 AM2/1/15
I might remind everyone that, as precautionary measures, I would recommend removing and discarding the sheet metal covering on the main PCB and also the plastic back cover.  The reason, folks, is for cooling.  The US FCC will not care about the tiny amount of RF leakage and the Cat's CRT assembly will benefit from the cooler environment.


Sent from my iPhone

California Electric

Feb 2, 2015, 1:11:34 PM2/2/15

Thanks for the replies.

For the battery replacement I tried the minimally invasive approach. I can verify that the following procedure worked (documented to help searchers in the future):

Unplug everything, turn cat upside down.
Remove screws securing metal plate
Tilt front edge of plate up, slide it forward to clear serial and parallel ports.
Paying attention to keyboard and power connections, carefully rotate the metal plate up.
The battery is right there at the corner. I removed two screws securing the shield and motherboard to the metal plate so that I could use my fingers to replace the 2032 coin cell.
Replace those two screws, verify keyboard and power are still connected and rotate the plate back down.
Paying attention to the clips on the parallel port, make sure the ports fit into the case properly and slide the plate into final position.
Replace those screws, flip the Cat back over, plug in and test.

I will follow up later on drive, rom and shielding questions that came up in the replies.

Thanks again,


Sent from my iPhone
> --
> You received this message because you are subscribed to a topic in the Google Groups "Canon Cat" group.
> To unsubscribe from this topic, visit
> To unsubscribe from this group and all its topics, send an email to
Reply all
Reply to author
0 new messages