Split I/D vs. Z8000

[Brandon Allbery]

Expires:

Quoted from <796 at tekcrl.UUCP> ["Re: cc(1): Questions about "-i""], by terryl at tekcrl.UUCP...
+---------------
| In article <374 at chinet.UUCP>, megabyte at chinet.UUCP (Mark E. Sunderlin) writes:
| > 
| >    My SYSIII machine has a -i option to its ld(1) command. It is described
| > as such:
| > -i	Seperate the program text and data areas when the output file is
| > executed.  Text occupies segement 0; its origin is 0x0000. Data and bss
| > occupy segement 1;data's origin is 0x0000. Bss follows data.
| > ...
| > If it means anything , I am running on a Zilog S8000 wih ZEUS 3.21 which is a
| > sysIII port.  
| 
|      Now to the -i flag to the loader. When you specify the -i option to the
| loader, the program instructions and data are NOT really mixed in among each
| other, even though it may look like that. What you have to remember is that
| a program running in VIRTUAL space actually has two address spaces to access:
| instruction space, and data space. Each space is separate (hence the name
| separate I/D) and independent of one another. It is up to the loader to
| link the file correctly with the correct address in either instruction space
| or data space, so the program can run correctly. It is then up to the opera-
| ting system to set up both sets of memory management registers (at least on
| the PDP) correctly so the program can run.
+---------------

Just one comment.  The Z8000 (to be precise, the Z8001) is segmented rather
similarly to the 8086; but the Z8001 can handle memory management.  As a
result, the PDP-11 style of memory management is used on Z8001's.

(Why Z8001?  The Z8000 doesn't have segment registers and can only address
64K.  Period.)

--Brandon
-- 
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