[Techtoolslist] Cat box, and fluke usage..

[John Robertson]

Kevin Moore wrote:

> Hi all, in my quest to learn more about using these tools, I've actually

> come up with a problem, and could use a little explanation.

>

> I'm working on a liberator board, and was using the atari cat box. The first

> two tests in the liberator manual have you check address lines. Well those

> checked out good. Next was the Data lines. This is where things fell apart,

> and I'm not sure what I'm seeing.

>

> Punch in address 0000, and write AA check the D0-D7 lines going to the ls245

> well half the incoming lines are the wrong state, and the output of the

> ls245 is non existent. Ie pins 2-9 have no output.

>

> So I hook up my fluke 9010a thinking there may be something wrong with the

> catbox, since this is the first time I've used it. Did the same basic setup

> wddis grounded, and Φ0 Φ2 shorted together. Do a write to 0000 with AA and

> use my logic probe to check. Same results.

>

> Am I to assume Bad memory at location 0000.??

>   

Yes.

Did you do the BUS Test first? That will show if any address or data 
lines are misbehaving.

If BUS Test is OK, and you get this problem for RAM @ 0000h, then try 
the next RAM set - say @ 0800h or 1000h (if RAM present - check Memory 
Map). If other RAM all checks OK, or ANY RAM checks OK, then the RAM @ 
0000h is certainly suspect.

If the RAM is 4-bit, then which bits are locked will tell you which RAM 
to replace.

John :-#)#

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