[Techtoolslist] Berzerk and Fluke 9010a

[John Robertson]

On 04/21/2014 12:19 PM, Grant Thienemann wrote:

> Hey Guys,

>

> I'm bound and determined to get my Berzerk working again. Currently I have

> it working to the point that the game will boot however the game will

> freeze randomly. List of things I have done:

>

> New sockets on the ZPU-1000 with new EPROMs and Z80 processor

> New ram sockets on the VFB-1000 and I have 4164 ram and 4116 ram that I'm

> looking into putting onto the VFB-1000.

>

> The BSC-1000 color board is fine, and the cleanest board I have on the

> machine.

>

> When I go to do the short ram check on my Berzerk board set, the 0-7FF

> fails, however the second one, 1000-17FF if I remember passes correctly.

>

> If anyone knows any tips or tricks with using the Fluke 9010a with a

> Berzerk board set I would appreciate it.

>

> Thanks

> Grant

> ____________


If the RAM test fails in one section, but not another then you likely 
have a problem with a RAM chip. If you have 4-bit chips then you can 
tell which it is by the error code - if it is X- that is the High 4-bit 
RAM, and if it is -X then that is the low 4-bit RAM. Where "X" indicates 
the bad read.

I use "55" and "AA" write then read to suspect RAM and this can show up 
the errors a bit faster.

Say you write 55 and then read 51 - that means the lower 4-bit RAM has a 
stuck bit (Bit 3 always low). Now you may get 55, so then you try AA 
which may give you A2 and again that indicates a bad lower RAM Bit 3.

John :-#)#
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