[Coco] Bad memory reported by Disto Coco III RAM Test by Tony Distefano

[Kip Koon]

Hi Michael,
I am so glad you figured out what the problem was.  Whew!  That was an easy fix.  

Kip Koon
computerdoc at sc.rr.com
http://www.cocopedia.com/wiki/index.php/Kip_Koon



> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Michael R. Furman
> Sent: Thursday, November 17, 2016 1:47 AM
> To: coco at maltedmedia.com
> Subject: Re: [Coco] Bad memory reported by Disto Coco III RAM Test by Tony Distefano
> 
> Thanks Kip, Richard, and Gene.
> 
> I figured out what the problem was.
> 
> I was using a brand new CocoSDC and it has a a jumper to connect the CART line to Q so you can use it to autostart ROM images in it’s
> onboard flash.  Well when I opened up the CoCoSDC package the jumper fell out on the floor and I absently found a place to connect
> it to without thinking and it wound up in the AUTO position.  The CoCoSDC manual clearly says not to do this to use SDC DOS. Oops.
> 
> 
> 
> —
> 
> Michael R. Furman
> Email: n6il at ocs.net
> Phone: +1 (408) 480-5865
> 
> 
> > On Nov 16, 2016, at 9:37 PM, Richard Goedeken <Richard at fascinationsoftware.com> wrote:
> >
> > I would suggest running my RAM test program:
> >
> > http://www.fascinationsoftware.com/media/Coco3_RAM_Test_v1.2.zip
> >
> > It will run continuously and print multiple errors, and give you the
> > values written and read back, so you may see a pattern.
> >
> > Richard
> >
> >
> > On 11/16/2016 09:25 AM, Kip Koon wrote:
> >> Hi Michael,
> >> Whenever a 512KB memory upgrade is installed in the Coco 3, the original 4 memory chips are removed and C65 & C66 are
> removed by cutting one leg and lifting up on the cap slightly.  That's the procedure I used when I added my 512KB memory board to
> my Coco 3. That upgraded Coco 3 is still running strong.
> >> As to the 8K address range that is bad, if an address line is truly bad, that 8K block would be bad everywhere, not just in one place I
> would think.  Maybe there is a logic problem somewhere maybe?
> >> Can anyone shed more light on this situation?
> >>
> >> Kip Koon
> >> computerdoc at sc.rr.com
> >> http://www.cocopedia.com/wiki/index.php/Kip_Koon
> >>
> >>
> >>> -----Original Message-----
> >>> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of
> >>> Michael R. Furman
> >>> Sent: Wednesday, November 16, 2016 11:37 AM
> >>> To: coco at maltedmedia.com
> >>> Subject: [Coco] Bad memory reported by Disto Coco III RAM Test by
> >>> Tony Distefano
> >>>
> >>> Does anyone have a manual for the Disto Coco III RAM Test by Tony Distefano?
> >>>
> >>> http://www.colorcomputerarchive.com/coco/Disks/Utilities/Disto%20Coc
> >>> o%203%20RAM%20Test%20%28Tony%20Distefano%29%2
> >>> 0%28Coco%203%29.zip
> >>>
> >>> I ran it on one of my Coco 3’s and it is returning an error, says
> >>> that block 60 is bad, which I interpret to be 0x78000 to 0x79FFF
> >>>
> >>> A second observation is that when loading certain programs in to
> >>> BASIC from the CocoSDC those programs get corrupted at the same place every time.
> >>>
> >>> I was looking at the schematics to try to figure this out and I am a
> >>> bit confused.  What I see on the schematic is each of the 256k x 1
> >>> chips on the 512 ram expansion board is attached to one data line
> >>> and there are two sets of chips selected by WE0 or WE1.  The part I
> >>> am confused about is what it means that a particular range of memory is bad.  If one data bit is bad across the entire 256k range I
> understand that one, that’s a bad chip. But it only seems to be bad in a particular 8k range of addresses, so maybe this is some issue
> with RAS or CAS or a flakey address line to only the WE1 set of chips?
> >>>
> >>> What would happen if C65 or C66 still in place?  Why do they have those RC filters on RAS and CAS anyway?
> >>>
> 
> 
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco