Mohammad,
I suggest you read the description of the Load Address instruction in
the z/Architecture POPS, The hardware ignores the HO bit in 24-bit and
31-bit addressing modes, and loads it as is in 64-bit mode.
As for 32-bit mode (TSS) I don't have a POPS for that architecture but I
suspect the HO bit is treated as any other. TSS did not use the "sign
bit" as a signal, just as an address bit.
HTH,
Steve Samson
Mohammad Khan wrote:
Mr. Samson,
Would you please clarify another point in this regard for me. Is it the
hardware that ignores the high order bit or the OS that plays some trick before
the address is sent out to hardware ?
Thanks in advance
Mohammad
On Mon, 5 Nov 2007 16:47:23 -0800, Steve Samson <[EMAIL PROTECTED]>
wrote:
A 24-bit program using fullword (24-bit) addresses in a variable length
parameter list will have the high-order bit on in the last such address.
This bit is ignored in addressing modes less than 64-bit. It is
significant in 64-bit mode, placing the address in the "dead zone".
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