When testing RAM and ROM chips in circuit electronic technicians use a fluke 9010A. They type in the address location to the RAM and ROM chips to check for errors or flags.

I only know of the fluke 9010A to test RAM and ROM chips in circuit, is there any of type of equipment that does this or another way to test RAM and ROM chips in circuit?

How does a tech know what the address is and location for each RAM and ROM chip that is on a circuit board to be tested?

The Fluke 9010A needs the address and location of which RAM or ROM chip you want to test, but where to find that information out is the hard part.

The Fluke 9010A floods the address lines, data lines, control lines to check for errors and flags.

The address lines, control lines, data line are always hexadecimal? never binary or octal?

 

Incorrect.

The address and data lines are always binary, never decimal, hexadecimal or octal.

You are being fooled if you think otherwise.

Ask the question, what is your bank balance on the bank's computer system?
Is it binary, decimal, hexadecimal or something else.
Guess what, it is binary!!!

How is the text that you just entered into your computer stored?
It is binary.

 

The Address mapping is addressed I think in hexadecimal

Most circuit boards don't come with the address mapping sheet, so how can you test the RAM and ROM chips without the address mapping locations?

The address mapping sheets tells the address buss locations, control buss locations and databuss lociations

 

What you see on the screen is hexadecimal. What you might enter from your keyboard might be hexadecimal.
This is converted into binary.

Another analogy. How much spare change is in you pocket? How many quarters, dimes, nickles and pennies (in the days when we did have pennies)? That is one way to represent the total sum in your pocket. Another way is to state the total amount in pennies.

Hexadecimal, octal and decimal are simply different ways of representing a value.

 

Most circuit boards don't come with the address mapping sheet, so how can you test the RAM and ROM chips without the address mapping locations?

The address mapping sheets tells the address buss locations, control buss locations and databuss lociations

If you not know the correct content of the RAM or ROM then you cannot verify its contents.

 

Most circuit boards don't come with the address mapping sheet, so how can you test the RAM and ROM chips without the address mapping locations?

You can't: if you don't know what should be there, you can't tell if it's right. The Fluke (or any tester) is for those who do know what they are looking for.

 

So how can I test the RAM and ROM chips in circuit or out of circuit without having the address mapping?

How do you guys approach testing and verifying ROM and RAM chips in circuit and out of circuit? what do you use for equipment

 

We don't test ROM and RAM chips. We have never had a reason to doubt their integrity.

 

Was it really possible to test RAM and ROM when it is soldered in the PCB?

I have an 48K Apple II plus, and if one of the DRAM chip is faulty, as long as it was not in the lowest row of the 48K memory map. I can test which 4116 DRAM is faulty using a test program from the Integer ROM card (DO ROM chip IIRC). But if one of the ROM chip is faulty, then I would have to replace them one at a time with a known good one.

In a PC, the only ROM nowadays is the BIOS ROM which can be an OTP eeprom or a flash ROM. If this chip is faulty, I dont think you are able to boot the PC and I see there is no way how a in-circuit ROM tester can determine that it was faulty or not. The only way I think is to swap it with a known good one, or re-flash it with a copy of BIOS program from the net.

As for the DDR ram in a PC, you can swap or replace them easily and they are all socketed.

In a musical instrument like keyboard. The ROM can be carrying the data of wave table to a tone generator or it can be carrying the main operating programs of the cpu of the keyboard. All of them are surface mounted and have a distance of 0.5mm between 2 adjacent pins and with different type of packages. Even in the service manual, the contents of them are not listed in it. I doubt how are you going to test them with a tester without those infos. The same goes with the static modern rams (multi-mega bytes) inside the keyboards.

Allen

 

here is a youtube video about the fluke 9010A to test RAM and ROM chips