[Coco] COCO3 System Arrangement of modules

[Gene Heskett]

On Friday 23 May 2008, John T Chasteen wrote:
>Gene
>Thanks so much for the detailed reply. I do have an ohmmeter. I did not
>check Cloud9
>recommended to place the two units that plug in MPI. Since I"M recovering
>from
>the Shingles and less than 30 days until my 80th birthday, it is hard to
>play for more
>than 4 or 5 hours at one time.

Hummph, I've been trounced, rather royally!  Here I was thinking at 73, that I 
was one of the older ones here.  Congrats John, and many more too.

>Thanks for the download saver. I hope I recognize the sockets you
>mentioned. I can't
>remember if I have a schematic. I hope pin one is printed on the circuit
>board.

Not on the bottom of the pcb, but on the 4 long (probably green) card sockets 
themselves, every pin is labeled right in the plastic molding, but its teeny 
stuff and one might need a good light and a magnifying glass if cataracts are 
in ones future.  It is beginning for me.

BTW, they now have a shot, a vaccine they are calling it, recommended for all 
over 60 to get it.  Unforch, it is also 150+ dollars, which for the retired 
crowd, might be hard to part with.  I am going to get it ordered for me as I 
had the shingles pretty bad a decade+ back after almost electrocuting myself, 
and have been in more or less constant pain since in the area of the rib cage 
and diaphram.  That is not a pleasant condition, just as yours wasn't a couple 
of weeks ago.

If medicaid doesn't cover it, yell, loudly, at your congress-critter.
 
>Thanks again for your help. I think I'll wait awhile before running
>jumpers, and see how things work.

If you put it online, and I used to use Supercomm for all my dialup access a 
decade or more back up the calendar, that, or one of the other "bypass the mpi 
for the irq's" hacks will need to be done.  Some even went so far as to run a 
separate wire, but that is not required, IMO is more dangerous, and this method 
is all out of sight.  And it Just Works(TM).  :)

>John
>
>On Fri, 23 May 2008 15:55:43 -0400 Gene Heskett
>
><gene.heskett at verizon.net> writes:
>> On Friday 23 May 2008, John T Chasteen wrote:
>> >Hello COCO Family
>> >
>> >I would like to get your opinions about a COCO3 System arrangement
>> >COCO3 with 6309 connected to an Upgraded MPI unit
>> >Place the Floppy in slot #4, Cloud9 SuperIDE unit with
>> >a Cloud9 configured CF unit and CFA (CF Adapter).
>>
>> John, I think you may be walking in pretty high grass there.  I
>> could be wrong,
>> but I think the boot device is hard coded to be in slot 4, although
>> a rebuild
>> of nitros9 after changing that code might be possible.  I think,
>> subject to
>> corrections, that the CF must therefore be used as an attachment to
>> the floppy
>> controller in slot 4, else the code that manipulates the slot
>> selector in the
>> mpi will switch you away from the CF access you want.
>>
>> Also, and here is a download saver, please open up the mpi and
>> jumper all 4
>> sockets so pin 8 is common to all, else os-9 will probably miss any
>> irq's
>> generated by incoming data from an i/o card in one of the other
>> slots.
>>
>> Doing this will also commonize the 4 irq pullup resistors located
>> near the front
>> edge of the mpi board, 3 of which should be removed as they
>> represent enough of
>> a load that some cards may not have enough stuff to pull the irq
>> line down, or
>> may blow the transistor doing it.  If that transistor is part of a
>> larger
>> integrated circuit, ooops.
>>
>> Those resistors are labeled r1, r2, r3 & r4 on one mpi I have, but
>> can be
>> identified by an ohmmeter connected to the socket's pin 8, and
>> probing them,
>> you should find 4 virtual short ( < 2 ohms ) circuits on one end of
>> each of the
>> correct resistors, remove 3 of them.
>>
>> By enabling the bypassing of the unselected slot's irq, so it gets
>> to the coco
>> regardless, the os itself will look for the source of the irq,
>> manipulating the
>> slot access until it finds the guilty card and will service the
>> interrupt with
>> no more than a 150 microsecond lag, more likely 15 to 20
>> microseconds though,
>> the 150 is absolute worst case I ever measured, and fast enough
>> you'll never
>> miss an incoming character from the rs-232 pack again.
>>
>> >I want save files from my Cassette tapes.
>> >Save files from 5.25 floppy disk.
>> >Transfer files to the CF or the CFA units
>> >Use the CF to boot.
>> >
>> >I would like to also use my Drive Wire cable to
>> >download files (disk images or files) from the internet
>> >or from my _PC hard drive.
>> >
>> >Do you see any bugs in this conciliation
>>
>> Just the caveats I pointed out, John.  Boisy, Robert, Mark or Alan
>> may correct
>> me, but that's how I've understood it for about 15 years. :)
>>
>> --
>> Cheers, Gene
>> "There are four boxes to be used in defense of liberty:
>>  soap, ballot, jury, and ammo. Please use in that order."
>> -Ed Howdershelt (Author)
>> "There is nothing new under the sun, but there are lots of old
>> things
>>  we don't know yet."
>>  -Ambrose Bierce
>>
>> --
>> Coco mailing list
>> Coco at maltedmedia.com
>> http://five.pairlist.net/mailman/listinfo/coco
>
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
It's better to be wanted for murder that not to be wanted at all.
		-- Marty Winch