simple sram question

[digitalundernet]

I can't find this answer on google or the data sheets. When sram says 2mb x 8 does this mean I need 8 chips to get 2mb or is the memory divided up into 8 byte blocks? I think Its  the former but I don't know for sure

[wkb]

Typically means 8 bit wide memory

[slateraptor]

Second wkb.

Furthermore, memory is typically specified as something like 2M x 8, not 2Mb x 8.

2M translates to 21-bit address space.
8 translates to each address being 8 bits wide.

Therefore, the SRAM has 16Mbit = 2MByte storage capability.

Another example for the sake of completeness: another 2MB specified chip can be partitioned as 1M x 16, which has a 20-bit address space.

[westfw]

I frequently see some memories described in terms of total capacity, and bus-width.  Usually ExPROMs, but still...
At 27C512 is a 512Kbit EPROM in x8 organization, for example.  A 24C04 is a 4kbit EEPROM.  And a 62256 is a 256Kbit Static Ram in x8 configuration.  It all depends on where the comma is.  "2k x 8" really ought to mean a 16kbit memory, but "2k, x8" is unfortunately common as well, and sometimes the comma is forgotten.

Read your datasheets.

[slateraptor]

I frequently see some memories described in terms of total capacity, and bus-width.  Usually ExPROMs, but still...
At 27C512 is a 512Kbit EPROM in x8 organization, for example.  A 24C04 is a 4kbit EEPROM.  And a 62256 is a 256Kbit Static Ram in x8 configuration.  It all depends on where the comma is.  "2k x 8" really ought to mean a 16kbit memory, but "2k, x8" is unfortunately common as well, and sometimes the comma is forgotten.

Read your datasheets.

Do you have a specific datasheet you can point to? Did a quick search on the devices you've listed and all appear to specify the standard <address space> x <data width> org convention. It sounds like you're talking about raw array blocks which require peripheral address decode; haven't seen those outside of a textbook description on programmable logic...then again, I'm not nearly as "seasoned" as some people around here.

The OP did disclaim his loss for an acceptable answer...I can see where he might be coming from considering how interpretation of the convention assumes an understanding of how memory devices are generally organized.

[westfw]

The part numbers themselves aren't enough?
I certainly hope the datasheets are clear enough; it's the marketing dialog and product summaries that tend to get ambiguous.  "24c04 4kb EEPROM chip" without a clear indication of whether that's kbits or kbytes.  Although, looking around, it does seem to be less common than I remember...

[slateraptor]

As previously mentioned, I performed a findchips search on all the part number you listed and looked at datasheets from multiple vendors, none of which showed the atypical specification scheme that you alluded to. Now it just sounds like you're referring to datasheet page-1 marketing rubbish and ambiguity in vendor-specific part numbers...in which case, disregard.

[westfw]

Ah.  I see.  When I said "read your datasheets", I meant that that was where correct and clear information would be, compared to the ambiguous "4kb eeprom" part description or part number, not that reading datasheets would find you examples of "problem" I was describing.