What is microcode ?

[mdmuazzam]

Hi,

   can anybody tell why microcode is used and when it started?.

freescale mpc8321E doest't have microcode whereas mpc8309twr board has.But why ?

Thanks

Muazzam(india)

[alexander_yakov]

Both mentioned devices have "Quicc Engine" communication co-processor, which handles some peripheral communication controllers without main core intervention. This co-processor is actually a RISC core running its microcode. This microcode may be pre-programmed in internal ROM or loaded to internal RAM at startup. MPC8309 processor does not have internal ROM, so QE microcode should loaded to internal RAM at startup.

Have a great day,
Alexander
TIC

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[mdmuazzam]

Hi Alex,

           So from your above answer do you wanna say that mpc8321 has internal ROM hence no need to load microcode since it's already has microcode feature with itself by gates and all.

Next , should i assume that HDLC controller(UCC5) works with almost no core intervention and it also assert interrupt to QEIC .So my question is QEIC has to assert interrupt to IPIC or not ? Since QEIC parent is IPIC.

Next, the irq handler which we register through request_irq() Kernel API ,it is executed by co-processor QE or Core processor?

Thanks

Muazzam(india)