19 Jan
2015
19 Jan
'15
1:07 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
duell
Sent: 19 January 2015 08:05
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: VT101 8085 CPU Fault
>
> I just found something interesting, the pin activity on the address
> lines, RD, WR, ALE etc appears normal for a bit, and only after a few
seconds
does it all become inactive.
>
> Perhaps this really is an indication that the ROM is bad, if it is
> getting into some kind of loop where it does no external activity. I
don't
really
know the 8085 to know whether that is possible.
What if (due to ROM or RAM problems maybe) the 8085 executed a HLT
instruction?
-tony
=
Good point. The S signals seem to tell you if it is halted, I will check
this evening.
I was trying to identify the chips on the board to see if I can identify the
ROMs but I can't find some of the numbers. The only socketed component is
marked CN55004N 8232 DEC TP03 23-028E4-00, could that be it? Anyone have a
datasheet for it? It would be good to try to read its contents.
Regards
Rob