The question, "which tools are better" has a number of qualifications that are not necessarily obvious.

1. Will you mainly write C or assembler code?

2. Do you have a program size limit? Will the tools you select keep your code within this limit?

3. Do you need any special features/functions that are unique to a specific compiler vendor?

4. How will you debug your application? Emulator, monitor, in-system debugger, simulation?

5. Do you need instruction set simulation?

6. Do you need on-chip peripheral simulation?

7. For the ADuC812, will you need compiler support for the extended address space? Do the tools support that or will you have to manually create code to handle that?

8. Is this the only 8051 project you will work on or will there be others? If you will work on other chips will the tools you select support all the features you'll use on those applications?

9. Will you need training? By that I mean do you already know the 8051 architecture or will you have to learn it? Do you need or would you like any special training for the tools? Do you need any special assistance? And, where will you get it?

10. How much are you willing to spend? If the answer is not much, then you should not expect much from the tools. Price is relative to the performance of the tools.

After you have answered these questions for yourself, you can begin to search the web sites of the various vendors to find out if they offer a product that meets your criteria.

Keil: www.keil.com
IAR: www.iar.com
Tasking: www.tasking.com
HiTech: www.htsoft.com
Raisonance: www.raisonance.com
Dunfield: www.dunfield.com

While investigating these web sites, you may learn about special features of a particular vendor that are important to you.

As for who generates the best code, most of these companies provide an evaluation compiler that lets you write and compiler real programs. You can create your own test code and then compare the output from the various compilers to ascertain which one YOU THINK generates the best code.

On the subject of price, one month of an engineer's time costs more than the most expensive 8051 C Compiler. The real question is "Will this C Compiler save me time and help me get my job done faster?"

Jon Ward
Keil Software