[Coco] Coco 2b problem: reboots when accessing the disk

[Luis Antoniosi (CoCoDemus)]

both tests fail. computer clicks and after some time the screen is gone.

so, do i need to replace the 6809 ? for a coco2b is pointless going for a
6309 right ?

On Tue, Feb 26, 2013 at 1:13 AM, Darren A <mechacoco at gmail.com> wrote:

> On Mon, Feb 25, 2013 at 10:15 PM, Luis Antoniosi (CoCoDemus) wrote:
> > Hi,
> >
> > I have this coco2b and when doing a DIR  with a FD500 it reboots with
> > garbled screen. If the drive is not connected it returns I/O Error.
> >
>
> That sounds like either the CPU's HALT or NMI lines are blown.  With
> the floppy controller connected, you can enter this one-liner to test
> HALT:
>
> POKE &HFF48,3:POKE &HFF40,128
>
> If HALT is working correctly, the computer should freeze for about 8
> seconds and then the OK prompt will return.
>
> To test both HALT and NMI together, you can use the following program:
>
> 10 POKE &H600,&H7C
> 20 POKE &H601,4
> 30 POKE &H602,0
> 40 POKE &H603,&H3B
> 50 POKE &H109,&H7E
> 60 POKE &H10A,6
> 70 POKE &H10B,0
> 80 POKE &HFF48,0
> 90 POKE &HFF40,&HA0
> 100 GOTO 80
>
> When you run this program the character in the top-left corner of the
> screen (standard 32 column mode) should increment once every 1.5
> seconds.  Again, a floppy controller is required for this test.
>
> Darren
>
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>



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