Re: Stellation Two - Mill 6809 card

["RedskullDC" <RDC@oz.org>]

Hi Michael,

"Michael J. Mahon" <mjmahon@aol.com> wrote in message 
E--dndCr75G1HZ_fRVn-hA@comcast.com">news:E--dndCr75G1HZ_fRVn-hA@comcast.com...

>> Could somebody please tell me what IC's are at
>> U6, and U14?
>
> On my Stellation Two "The Mill" card, U6 is a 74LS14
> and the U14 socket has a daughterboard with two IC's
> and a switch plugged into it which is an "OS9 ROM
> Interface".
>
> It looks like one of the chips on the daughterboard
> was originally in the U14 position--a 74S288, perhaps,
> but the other daughter board chip is a 74LS367, and
> it is possible that the chip originally in the U14
> socket was neither of these.

Thanks for your help with this.

>
> The ROM socket at U11 is empty on my board--does yours
> have a ROM?
>
Mine doesn't have a ROM either.

Having a quick look at the back of the circuit board where the
ROM is, you will see a large trace between pin 24 and 21.
You could fairly safely say that it has to be either a 2716 or
a 2532 which both require VCC on pin 21 to operate.

I haven't checked the A11 trace to see exactly which EPROM
is required.

Cheers,
Red