[Coco] Weird CoCo3 problem...

[Mike Pepe]

I've never seen this particular issue before, but from what you describe the only thing I can think of is the SCS signal is not making it into the cartridge itself. I wonder if a different I/O pak such as the RS232 pak is functional on this system or not.




> -----Original Message-----

> From: coco-bounces at maltedmedia.com [mailto:coco-

> bounces at maltedmedia.com] On Behalf Of Brian Blake

> Sent: Saturday, January 02, 2010 6:05 AM

> To: CoCoList for Color Computer Enthusiasts

> Subject: Re: [Coco] Weird CoCo3 problem...

> 

> Hi Mike,

> The answer to both of those is 'yes'.

> 

> I tried Tetris and it worked fine.

> I also tried the POKE on the CoCo3 with the C9 512k upgrade and the

> Drive 0 light did come on.

> --- On Sat, 1/2/10, Mike Pepe <lamune at doki-doki.net> wrote:

> 

> From: Mike Pepe <lamune at doki-doki.net>

> Subject: Re: [Coco] Weird CoCo3 problem...

> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>

> Date: Saturday, January 2, 2010, 2:10 AM

> 

> 15KHz sounds about right for a loop like that. Every poke to that

> address should drive SCS low momentarily.

> 

> Two other things come to mind for checking- if you put this

> controller/drive on another machine, does the poke make the drive

> activity light come on? Second thing is- do any other cartridges work

> on this machine? Any game paks to test with?

> 

> 

> > -----Original Message-----

> > From: coco-bounces at maltedmedia.com [mailto:coco-

> > bounces at maltedmedia.com] On Behalf Of Brian Blake

> > Sent: Friday, January 01, 2010 9:08 PM

> > To: CoCoList for Color Computer Enthusiasts

> > Subject: Re: [Coco] Weird CoCo3 problem...

> >

> > Hi Mike,

> >

> > Here's what I did - not sure if it was correct:

> >

> > 10 POKE &HFF40,1

> > 20 GOTO 10

> > RUN

> >

> > I then checked pin 6 of IC9 - which according to my schematic is the

> > /SCS line - HI reading on my DMM in logic mode (<1 = LO, >2 = HI, in

> > between it shows the voltage).

> > I then checked pin 40 on the 6809 - the /HALT line - and got a

> reading

> > of 1.545vdc.

> > Not sure if my DMM would react fast enough, I changed to Frequency

> mode

> > and checked pin 6 of IC9 again - got a reading of about 15-kHz.

> > I hit the break key and checked pin 6 again, and it was still HI.

> > Shut of the CoCo, waited a few seconds and turned it back on, checked

> > again and it was still HI.

> > Checking pin 36 on the slot yielded similar results, except the

> > frequency was very different ~110-kHz.

> >

> >

> >

> > ________________________________

> > From: Mike Pepe <lamune at doki-doki.net>

> > To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>

> > Sent: Fri, January 1, 2010 9:45:14 PM

> > Subject: Re: [Coco] Weird CoCo3 problem...

> >

> > I'd put that POKE &HFF40,1 into an endless loop and look to see if

> the

> > SCS line on the cartridge port is stuck high or if it pulsates.

> >

> > Radio Shack used to sell a pretty decent logic probe for about $20.

> Not

> > sure if they still do, but it would help diagnose the problem in this

> > case.

> >

> > The latch at $FF40 should function independently of a blown out 6809

> > HALT line which is what usually indicates a CPU replacement.

> >

> > > -----Original Message-----

> > > From: coco-bounces at maltedmedia.com [mailto:coco-

> > > bounces at maltedmedia.com] On Behalf Of Brian Blake

> > > Sent: Friday, January 01, 2010 4:48 PM

> > > To: CoCoList for Color Computer Enthusiasts

> > > Subject: Re: [Coco] Weird CoCo3 problem...

> > >

> > > Nope - no logic probe. What kind of signal should be seen there? My

> > DMM

> > > has some logic functions built into it, but, I'm not sure off hand

> > what

> > > it's capable of...

> > >

> > >

> > >

> > > ________________________________

> > > From: Mike Pepe <lamune at doki-doki.net>

> > > To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>

> > > Sent: Fri, January 1, 2010 7:39:58 PM

> > > Subject: Re: [Coco] Weird CoCo3 problem...

> > >

> > > That's pretty strange. If you have a logic probe you can do some

> more

> > > investigation. The LS138 chip may be faulty.

> > >

> > > > -----Original Message-----

> > > > From: coco-bounces at maltedmedia.com [mailto:coco-

> > > > bounces at maltedmedia.com] Ong happens accept an I/O error - not

> > light,

> > > no

> > > > disk activity, nothing...

> > > >

> > > >  Behalf Of Brian Blake

> > > > Sent: Friday, January 01, 2010 3:24 PM

> > > > To: CoCoList for Color Computer Enthusiasts

> > > > Subject: Re: [Coco] Weird CoCo3 problem...

> > > >

> > > > Tried the POKE and no drive activity light came on. Anytime I try

> > to

> > > > access the disk, nothin

> > > >

> > > > ________________________________

> > > > From: Mike Pepe <lamune at doki-doki.net>

> > > > To: CoCoList for Color Computer Enthusiasts

> <coco at maltedmedia.com>

> > > > Sent: Fri, January 1, 2010 6:08:28 PM

> > > > Subject: Re: [Coco] Weird CoCo3 problem...

> > > >

> > > > I suspect the 6809 as well. But if you do a poke &HFF40,1 the

> drive

> > 1

> > > > activity light should go on. If not something else may be wrong.

> > > >

> > > > > -----Original Message-----

> > > > > From: coco-bounces at maltedmedia.com [mailto:coco-

> > > > > bounces at maltedmedia.com] On Behalf Of Brian Blake

> > > > > Sent: Friday, January 01, 2010 2:36 PM

> > > > > To: CoCoList for Color Computer Enthusiasts

> > > > > Subject: Re: [Coco] Weird CoCo3 problem...

> > > > >

> > > > > Hi Arthur,

> > > > >

> > > > > Unfortunately, it's not socketed. Tho, I have about 9 6309's

> and

> > > > plenty

> > > > > of sockets... hmmmm.... maybe tomorrow....

> > > > >

> > > > >

> > > > >

> > > > > ________________________________

> > > > > From: Arthur Flexser <flexser at fiu.edu>

> > > > > To: CoCoList for Color Computer Enthusiasts

> > <coco at maltedmedia.com>

> > > > > Sent: Fri, January 1, 2010 3:56:15 PM

> > > > > Subject: Re: [Coco] Weird CoCo3 problem...

> > > > >

> > > > > I vaguely recall something like this happening to me years ago

> > that

> > > > was

> > > > > fixed by replacing the 6809.  If this machine and one of your

> > > others

> > > > > has had

> > > > > the 6809 socketed, it would be easy enough to swap in a 6809

> from

> > > one

> > > > > of the

> > > > > other machines and see if the problem goes away.

> > > > >

> > > > > Art

> > > > >

> > > > > On 1/1/10, Brian Blake <random_rodder at yahoo.com> wrote:

> > > > > >

> > > > > >

> > > > > >

> > > > > > All of these new developments on the CoCo front finally lit

> the

> > > > fire

> > > > > under

> > > > > > my arse to set up real hardware again. Besides my repack

> > project,

> > > I

> > > > > have 3

> > > > > > other CoCo3's, two with 512k upgrades (one C9 and one PBJ)

> and

> > > one

> > > > > 128k. The

> > > > > > one with the C9 upgrade works fine - can load and play

> > > Sockmaster's

> > > > > Donkey

> > > > > > Kong.

> > > > > >

> > > > > > The one with the PBJ upgrade, not so... At boot, it comes up

> as

> > > it

> > > > > should

> > > > > > with the proper display. However, any floppy commands are met

> > > with

> > > > no

> > > > > > response from the floppy drive (with an FD-502 controller) at

> > > all.

> > > > > Almost

> > > > > > like the drive is off. The drive responds as it should in the

> > > other

> > > > > two

> > > > > > machines. Upon removing the top case and k/b, I saw two

> wires,

> > > each

> > > > > had been

> > > > > > soldered to opposite sides of R23. Now, under the keyboard,

> is

> > > > > another wire

> > > > > > with alligator clips on each end, and the clips are holding

> on

> > to

> > > > the

> > > > > bare

> > > > > > end of the wires soldered to R23, effectively bypassing the

> > > > resistor.

> > > > > I'm

> > > > > > looking for the PBJ instructions, pretty sure I have them, to

> > > find

> > > > > out if

> > > > > > this is called for. I can also see where C65 & C66 have been

> > cut

> > > > and

> > > > > > re-soldered. I have reseated the GIME and the PBJ memory

> chips,

> > > and

> > > > > cleaned

> > > > > > the 40 pin connector.

> > > > > >

> > > > > > Any other suggestions? My 100MHz o'scope bit the dust so I

> > don't

> > > > have

> > > > > that

> > > > > > tool any more (anybody have a CRT for a Leader 3 channel

> 100MHz

> > > > > scope??)

> > > > > >

> > > > > >

> > > > > > Thanks,

> > > > > >

> > > > > > Brian

> > > > > >

> > > > > >

> > > > > >

> > > > > >

> > > > > >

> > > > > > --

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> > > > >

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