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HP/Agilent 1675x logic analyzer card memory up-hack
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gslick:

--- Quote from: MarkL on November 28, 2017, 06:55:49 pm ---Does your 16740A have the same amount of memory populated as a 16752B?  The 16752A has 34 x Micron 48LC4M16A2-8E (4M x 16).

--- End quote ---

I just took a look at the 16741A that I have. It has (34x) MT48LC4M16A2-75 64Mb (1 Meg x 16 x 4 banks) parts. So if my math is right that should be sufficient for 32M samples of 68 channels, even though the 16740A, 16741A, and 16742A are 1M, 4M, and 16M analyzers.
MarkL:

--- Quote from: gslick on November 28, 2017, 10:23:38 pm ---
--- Quote from: MarkL on November 28, 2017, 06:55:49 pm ---Does your 16740A have the same amount of memory populated as a 16752B?  The 16752A has 34 x Micron 48LC4M16A2-8E (4M x 16).

--- End quote ---

I just took a look at the 16741A that I have. It has (34x) MT48LC4M16A2-75 64Mb (1 Meg x 16 x 4 banks) parts. So if my math is right that should be sufficient for 32M samples of 68 channels, even though the 16740A, 16741A, and 16742A are 1M, 4M, and 16M analyzers.

--- End quote ---
Your math is right: 34chips * 4M*16/chip = 2176M/68ch = 32M/ch

Plus you have the -75 version which is a 133MHz part and I have the -8E part in a 16751A which is 125MHz, so it would be reasonable to assume the upped 1674x cards can also do the full sample rate of 400Msa/s.  Some verification testing from DocBen (or yourself, if you feel like playing with it), would tell for sure.

That must have been some pretty fine segmentation in the market to make Agilent produce 6 different performance levels on essentially the same hardware.  Go sales team!
gslick:
There is flux residue around the pads of two of the unpopulated resistors on my 16741A module. I wonder if those resistors were populated during manufactured and initial testing in a maximum configuration and then removed when the module was configured to be a 16741A.

Does someone have a photo of a 16742A for comparison?
DocBen:
Well it makes a lot of sense to have the exact same hardware, because it effectivly eliminates testing and designing of different products and eliminates the need for early product differentiation.
So you can buy in bulk.

I didnt try to solder in all resistors, but it will probably not be recognized by the analyzer (factory test setting?)

Also if you think about: the memory is run of the mill Pc100/PC133 memory not even special temperature range or rad hardend. Even if they built 10000 cards thats not even 500k chips for the whole lifetime of the cards. A PC manufacturer back in the day probably used that per day or per week. Micron probably asked when they would stop sampling and start buying  ;)

I guess thats also the reason why all the other chips come in multiples: it is just cheaper (or you cant even get them in lower quantities).

@gslick: I think that card was originally a different model. might have been a 16750b not sure.
forgot to take a picture of my card when I modded it to be a 16742a but I think R68 belongs at R63 not sure. ebay constantly wants to give me a free iphone so I cant look at the pictures of 16742a there right now, but you can give it try
DocBen:
I just checked what kind of equipment you need to actually verify specs (from the service guide):
- a pulse generator with 200 MHz (still reasonable) with 2.5 ns pulse width and < 600 ps rise time (and i'm out)
- a digitizing oszilloscope (check) with >= 6 GHz bandwidth, < 58 ps rise time (and i'm out)

so at least an "offical" verification is off the table for me.

I might do some experiments with an FPGA ( upduino when (if) I get it ) as it supposedly has a 275 MHz PLL onboard that can drive an I/O pin. Maybe clock doubling with an XOR gate from potato semi and a clock buffer. That setup could in theory reach 800 MHz but I don't have an oscilloscope that can verify that so  :-\
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