I met a question during my sample test.
In my opinion, a RAM will change its content when you write the data into it.But I found that read option alone will sometimes change the content of the RAM. So could anybody tell me why this happens? Or is this related to the foundary 's RAM?
If what you say is true, no electronic device with RAM should work reliably ..
Remember, these things are not cleaver at all and if YOU make a mistake (software or hardware) .. BOOM!!!
Back to your case: several issues involved - timing problem (R/W pulse to short, to long, ....), two or more devices accessing data/addres bus at the same time, de-coupling of the (+)Vcc/Vdd line ..... and so on ..
I think it does not need to be discussed. If the value is changed in read process, it must has something wrong. Just check your RAM model or your stimulus to the RAM.
This cannot happen with any RAM, but if it's taking place, as is just said synchronize your operations or You are accidentally writing something into RAM. In big designs, when we deal with number of dedicated RAMs for different components, Synchronizing all of them becomes an issue sometimes.
Hi...
What you are asking is that "RAM content changes when you read it !!"..
This is the pratical problem in SRAM .. This can happen when the Noise Margin of the cell is not large and the read operation is sufficient to make it trip....
In case you are interested in the papers you can search for static nosie margin in SRAM cells in case your RAM is Static (6 transistor RAM)
I think you should make it clear whether the RAM is DRAM or SRAM, or it's actually on-chip cache. There is a big difference between DRAM and SRAM.
Another thing is what it's the speed of RAM you're using. If it's high speed, there is a possibility that your IO timing does not have enough margin which may cause some
wired thing happens.
I think that you first check what RAM you are using and its characteristics.
If your RAM changes its values in read operation, it may have faults: either RAM itself or the surrounding circuits.
read operation itself can't change a normal ram's content, your ram
may has been damaged.
sunms said:
I met a question during my sample test.
In my opinion, a RAM will change its content when you write the data into it.But I found that read option alone will sometimes change the content of the RAM. So could anybody tell me why this happens? Or is this related to the foundary 's RAM?