Re: BCC, ELKS 24 Bit addressing mode

[Segin <segin2005@gmail.com>]

Serdar Sutay wrote:

> Dear All,
>
> I am porting ELKS to a special version of 80186 to be used in embedded 
> devices. This special version known as Turbo186 is using 24 bit 
> addressing using a special addressing scheme. So I need to modify bcc 
> or as86 to support 24 bit addressing mode.
>
> This type of operation is common in embedded usage. 24 bit addressing 
> is working like this,
>
> In normal 20 bit addressing when far jumps are used, two 16 bit 
> operands are given for address calculation. First operand is left 
> shifted 4 bits and added to second operand, then 20 bit address is 
> calculated.
>
> In 24 bit addressing mode, first operand is left shifted 8 bits and 
> added to second operand, resulting in 24 bit address.
>
> What am I required to do to support 24 bits addressing in bcc? Can you 
> give me some insight or guide me to the correct person?
>
> Thank you for your consideration and help.
>
> Kindest regards,
>
> Serdar Sutay
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Basically you're working with a 286 that's been lobotmized down to a 186 
with the addressing features in place?