What's the meaning of these specifications?

[jetset]

In the datasheet of my CPLD, it says this:

Typical gates (logic and RAM) = 10,000
Maximum system gates = 31,000

What does these specifications mean?
I mean what is the number of typical gates, and what is the number of maximum sysem gates?? What's the difference??

 

[echo47]

Excerpt from A1tera's "AN 110: Gate Counting Methodology for APEX 20K Devices":

Typical gate count is the capacity metric indicating the gate array size that can be implemented in an APEX 20K device. Typical gate count assumes that a design uses the logic array and the embedded array. It also assumes that portions of the embedded array are used for both memory and logic functions.

Maximum system gate count is the number of gates when 100% of the ESBs are used as memory. This measurement approximates the gate counting method used by field-programmable gate array (FPGA) vendors when determining “system gates”.

 

[javad]

Dear friend,
A system gate is a standard for representing the number of two input NAND gates that can be emulated using this device. Remembering that the NAND gate is the "universal" gate and that any logic device can be built with enough of them. For example if you have cpld with 1,500 system gates, this is another way of saying that this device can make any project that can be made with 1,500 NAND gates.

For more information see :
**broken link removed**
which contains good lab lecture notes that can help you more!