Oric computers, My oric don' t boot

Hi,

I've just got an Atmos and when i start it i just see a cursor on a frozen
screen. The cursor is at the right bottom of the screen.
To describe a little bit more :

1) When i power on the atmos, i've the classical boot screen with the black
screen and some white chars on it.
2) After that (1 sec app) the screen goes blank and the cursor stay in the
right bottom of the screen.
Normally just after that the oric should display de 37631 bytes free screen.
I've changed the Rom with an other Atmos and it's still the same problem. On
a working atmos the rom of the non working computer works fine.
The Motherboard is a Rev 3 one.


Did someone know what may be wrong ?

Thanks
Philippe
http://www.cmpi.fr.st

"CMPI" < XXXX@XXXXX.COM > wrote


Are you turning on the power and then pluging in to the Atmos ? That can
help. If you have it connected and switch on it may not boot.

Possibly a faulty DRAM chip - check to see if any are warm.

Try going through the service manual. Available in French and English.
http://www.48katmos.freeuk.com/projects.htm

Steve M

"CMPI" < XXXX@XXXXX.COM > a rit dans le message de

black
screen.
On

This is not a cursor but a text attribute which is written in $BFDF (right
bottom of the screen),
and this is typical of a faulty VIA.
The routine that switches to text mode first write this attribute in $BFDF
and then waits 3 VIA interrupts to be sure 20ms has elapsed (ie. to be sure
the ULA has read this attribute when scanning the screen).
When the VIA is broken, no interrupt occurs, and the routine waits
forever...

Cheers,

Fabrice

Ok ... So if I follow you the 6522 Chip under the 6502 proc is out of order
....

Is it possible to test it with a multimeter to be sure of that ?

Anyway thanks for your answer !!

Best Regards
Philippe

In article <4198f58b$0$10730$ XXXX@XXXXX.COM >,



A multimeter is unlikely to help, sadly. An oscilloscope may help you to
see what's happening, but without some known "good" signals to look at
you may find nothing of use. If the chip is broken, it may not be obvious
by just looking at signals on the legs.

If you can get a spare 6522 chip (eBay?) then removing the old 6522 and
replacing it (preferably with a socket, while you're at it) is the best
way to go. The socket allows you to change it again in the future, as
removing the chip and replacing it stresses the PCB. You only want to
do this once :)

--
--------------------------------------+------------------------------------
Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/

"CMPI" < XXXX@XXXXX.COM > a rit dans le message de

order

Yeap... if you have this image on screen, there are chances that the 6522 is
the *only* chip out of order ( http://oric.free.fr/IMAGES/Screen7.bmp )


I wouldn't know how, most signals are transient ones...
But you can try the diagnose rom I have written
( http://oric.free.fr/ROMS/diag.rom )
Its function is to point out which ram chips are faulty, but it will also
tell you if the VIA is out of order...

Cheers,

Fabrice

YES It's EXACTLY the screen i have !!!

Gonna look for that damned 6522A .... and a socket for it of course !!

Thanks to everybody !!!

Philippe
www.cmpi.fr.st

Ps: Great job fabrice for euphoric !!


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