HP 9845 C with 280 option startup failure

[Dwight K. Elvey]

>From: "Tequi Lizer" <tequilizer at gmx.net>
>
>I recently acquired a HP 9845C option 280 (was looking for it for a 
>really long time).
>
>The machine is in an overall good condition, however it hangs during 
>memory test ("MEMORY TEST IN PROGRESS"), even after cleaning all board 
>connectors, resocketing all ROMs & repeated control-stop's. Before 
>entering nirvana the printer outputs a couple of memory addresses. 
>Although lots of defects may be responsible, I assume there is a 
>combination of both a bad RAM chip and a ROM failure, since a RAM defect 
>alone should (?) not crash the system during the test.
>
>The printout looks like this:
>
>000000 100112 052525
>000000 110112 052525
>000000 120112 052525
>000000 130112 052525

---snip---

Hi
 It looks like it is more likely that you are having a data bus
buffer or address buffer issue than a massive RAM/ROM failure.
You might look at things with a 'scope or logic analyser.
Dwight