[Coco] NitrOS9 driver for Tandy RS232 Pak?

[Gene Heskett]

On Monday 29 December 2008, Steven Hirsch wrote:
>On Mon, 29 Dec 2008, Gene Heskett wrote:
>>> Only one respondant mentioned the need to remove the EPROM from the
>>> Program Pak.  I'd rather not damage the label to extract the case screw
>>> unless absolutely necessary.  Can anyone confirm that removal of the
>>> internal EPROM is, in fact, a requirement under NitrOS9?
>>
>> Yes.  In fact I am amazed that it is still intact and in place.  It may
>> already have been removed.  IIRC, it contains some sort of a broken, never
>> was supported by anybody, autobooting vid-text terminal program.  IIRC
>> that is, please understand its been 2+ decades and many many such case
>> openings for mine.
>
>I'm not seeing an EPROM in this unit.  Holding the PCB with the DB25F
>connector facing me, there's a 6551 ACIA chip on the right and a 24-pin
>chip on the left labeled 'SCM95046P.  Is that a masked ROM carrying the
>firmware?
>
It could be, google for it.  The acia (6551) only needs a pair of MC14xx chips 
for level translation, its 74ls** adress decodeingaddress decoding, and a 
crystal.  Another 24 pin chip would have to be that rom.

>Would like to be sure before warming up the desoldering station!
>
>> Mine no longer has the little tin can power convertor either as it
>> smoked itself at least 15 years ago, so mine is rewired and must live in
>> an MPI for power purposes.  It also has the piggy backed kit which I use
>> for a serial mouse now.  Sweet.  I also used it for a 2nd midi port with
>> ultimuse for a while, but ultimuse never grew a recording function, so the
>> mouse won.
>
>What piggybacked unit is this?

That is where you piggy back another 6551 on top of the existing one, but its 
chip select logic enables it in the next 4 byte wide address block, usually 
by grabbing an adjacent pin on the address decoder.  The MC14xx chips are 
also stacked.  I brought out a db9 connector on the side for it, so the 
seriel mouse plugs right in.

Its a fairly commonly done method to make a dual serial port device out of it, 
and I believe there is probably a howto on rtsi, but I've NDI what its 
filename would be.  Can someone bail me out that has done this more recent 
than I?, since its been probably 20 years and memory fades from lack of 
refresh at my age.  About all I can recall ATM is the 2 or 3 feet of wire 
wrapping wire it took to do all that.

It may even be in one of the Rainbows.

>Steve



-- 
Cheers, Gene
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