[Techtoolslist] ADDR ERROR @ XXXXh - LOOP? = Address line issue

[John Robertson]

I should mention this is a Fluke 9010A running with a 6800 pod - testing 
Bally MPU, which board being tested shouldn't matter though...

On 2021/03/24 12:46 p.m., John Robertson via Techtoolslist wrote:
> On 2019/01/11 5:25 p.m., John Robertson wrote:
>> And here is a new one for me, don't recall seeing that error message 
>> before, nor can I find reference to it in the 9010A Operator Manual.
>>
>> Pressing the MORE key gives me "ADDR BITS 0100 - LOOP?" so I assumed 
>> this was some sort of a decode issue and will proceed accordingly. 
>> Just thought I would post it here in case anyone else runs across 
>> this rare error message which I assume was added to the 3A ROMs in 
>> the 9010, but not to the manual - at least the copy I have...
>>
>> (later) It was indeed a problem with some address lines. For only A7 
>> and A8 when loop reading @ 0000 (easiest - all should be Low) with 
>> the 9010 probe (set to Address) the Low light was flickering, not 
>> steady Low. Turned out to be a 74LS367 that had two inputs that were 
>> somehow pulling the lines slightly high. This did not show up when 
>> doing a ROM or BUSS test - only in either of the RAM tests.
>>
>> FYI
>>
>> John :-#)#
>>
> Still later.
>
> Ran into this "ADDR ERROR @ 0000-LOOP? again, this time it was an 
> Address line (A5) shorted to a Data line (D7). It doesn't matter which 
> Data line the address line is shorted to, it gives the same message:
>
> Any Data line shorted to A0 gives/More ADDR BTS 0001-LOOP?
> Any Data line shorted to A1 gives/More ADDR BTS 0002-LOOP?
> Any Data line shorted to A2 gives/More ADDR BTS 0004-LOOP?
> Any Data line shorted to A3 gives/More ADDR BTS 0008-LOOP?
> Any Data line shorted to A4 gives/More ADDR BTS 0010-LOOP?
> ...
> Any Data line shorted to A15 gives/More ADDR BTS 8000-LOOP?
>
> FYI.
>
> John :-#)#
>

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