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Hello,

My name is Marcel and I am new on this forum, I have a question about the following:

I am working on a 16 bit application for a AM186ES processor (x86 compatible), this processor has no internal ROM or RAM. My application will be stored on a PC-Card from which the processor directly can execute the code.
One purpose of the program is to test the RAM memory which is externally mounted on the PCB next to the AM186ES, now is my question, how can I create stack after I have tested my RAM memory, the standard keyword STACK declares the stack before the program is executed, but I want to create the stack (dynamically) after my program has checked the RAM memory.

Another question, how does my AM186ES now where to create the stack, it can address max 1 MB but it is connected to a flash as well, how does the AM186ES know at which address the RAM memory is located? Do I need to set the ss register to the (base) addres of the RAM?

And the last question, I have declared some global variables in my data segment, does the AM186ES store this variables on the stack or on my PC-Card? If on my stack, how can I "delay" this till my RAM is checked, as mentioned above.

I use a TASM assembler for the project.

Thanks for your help,

Marcel

1.stack is creating with initialisation of ss:sp only. if you wish to test memory first, you may use ram-less call trick in your code:

replace with:

this trick is used in bios on the first stage when memory is not used yet. look into any bios to check how does it work. you may use also far procedure call, just put value to "restore" cs also into that local "stack"

2.your cpu has no brain to differ ram from rom. it is the task of your software. just place ram into the start of adress range, and rom into the end of it. cpu will need ffff:0000 adress in rom after reset and ram starting from 0000:0000 for interrupts vectors (if they are in use in your device, of course)

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look there: you may found a code there to blink through lpt on 386 board without installed memory at all: http://www.winasm.net/forum/index.php?showtopic=770
it is generally useless, but works, so, can be used as test

This post has been edited by shoorick on Dec 7 2009, 07:11 AM