🚀 go-pugleaf

In article <358@sky.COM> hamill@sky.UUCP (John Hamill) writes:
>
>	Does anyone out there know how to play with memory beyond 64k
>in a PDP-11 running RT-11SJ? I know there is a RT-11XM that can use the
>extended memory, but I don't have a copy. I'm running PDP-11/23's on Q-bus
>and need to address devices beyond the 16 bit boundary. The PDP-11/23 uses
>18 bit addressing on the bus but can't be talked to as far as I can tell.
>Specifically, I need to talk to 0x20000 (hex) using a Whitesmith C compiler.
>Any suggestion would be appreciated to the maximum. Please reply through
>E-mail.

The easiest way to use the extra memory with RT-11SJ is to use the VM device
driver to access it as RAM disk.  Then you can use the standard file I/O
routines.  Otherwise, you have to manipulate the MMU registers yourself.

I have done this in MACRO with partial success.  I was able to access memory
just fine, but had to disable all interrupts to do it so that the monitor
wouldn't crash by having the I/O page mapped out when it needed it (thats
where I put my 'window' into the extended memory.

--------------------------------------------------------------------------------
Bradley's Bromide:
	If computers get too powerful, we can organize them into a
	committee -- that will do them in.
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Dr. Jon Brinkmann			Internet:	jvb7u@Virginia.EDU
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