[Coco] AT306 Mouse and Keyboard

[Paul Fitch]

> Six months later I had heard nothing from Kevin. Several 
> phone call where he was always at work and many email 
> messages I finally got a message that said, "He had 
> everything working except the  mouse and didn't have a scope 
> to check it with."
> 
> I told him I was a keyboard  person and did not own a mouse 
> (I didn't) go ahead and return it.
> 
> I used it that way until The Coco Birthday Pennfest when I 
> bought my Linux system from Ron Bull.
> 
> Here again, IIRC.
> The manual in the introduction says the idea behind the 306 
> was to use readily available parts and devices for an OS9 
> based computer. Isn't there a plug next to the keyboard plug 
> for the mouse.
> 
> Standardization.
> 
> Tight code,
> Dave
>

No mouse plug near the keyboard plug.  Just the 3-pin header by the SuperIO
chip.

The layout diagram in the AT306 manual shows the MDAT and MCLK lines coming
off the SuperIO chip, but the lines just end.  No terminaion or grounds, or
anything.

I pulled the data sheet off the web for the PC87303 IAT VUL that is on the
motherboard.  The KBDAT is connected to pins 95 and 141 of the SuperIO chip.
The KBCLK is connected to pins 96 and 4.  The MDAT is connected to pins 94
and 142, and MCLK is connected to pins 93 and 3.  The RTC is on pins 8-10.
I don't have a big enough magnifying glass (the eyes are going) to see any
damage to the traces coming off the chip in the area of pins 3-10.

Still, after further play, I'm sure the problem is somewhere along in there
for the following reasons:

1) the Kernal error said it couldn't start the RTC, not that the time was
wrong.  

2) The keyboards (AT with full size connector and the PS/2 to AT converter)
both showed the numberlock light on bootup.  That tells me that the keyboard
is getting its + and - power.  The only two lines remaining are the KBDAT
and KBCLK. 

Question for all:  Would the RTC fail to keep any time at all if the battery
was dead?  And if theres no internal clock, would that affect the KBCLK
signal?

I made a mistake earlier, the CR2025 is a 3v lithium not 5v like I
originally thought (please refer to eyes going bad statement above).  Anyone
know if a CR2032 (which is the same form factor) could be used in its place.
I don't want to do any damage I can avoid, but I'm thinking my problem with
the keyboard could be traced to a dead RTC battery?