What does PUSHJ do? - test-drb@ccmp.vtda.org

21 May 2005

...
 Subject: Re: What does PUSHJ do?
   From: Johnny Billquist <bqt at Update.UU.SE>
   Date: Sat, 21 May 2005 12:47:45 +0200 (CEST)
     To: cctalk at classiccmp.org

Ah! That explains it. :-) 
I do have a PCdos compatable asm that is pretty neat but for little stuff
the eyeball does it fast enough. ;)

One day when time permits a RS08 equivelent will be made for the 8f
and I'll start running real software.

...
   I've used
one that did.  Might have been a hack.  The 6120 however does
 and the DEC purchase spec is clear on that too. It's still done with IOTs. 
Must have been some additional hardware. One brain cell seems to think
that DEC maybe sold some hardware to implement stacks on the pdp8, but it
might have been the pdp-12 as well.
But yes, the 6120 did have IOTs for that.

I have several PDP-8/A systems around, but no 6120 systems... 
I have no PDP-8a.  I do have three 6120 based systems, two DECmateIII
and a homebrew using the chip.  The 6120 is the second generation of the
6100 PDP-8 in CMOS.  It adds EMA and stacks via IOTs in hardware.  Runs 
OS/278 flavor of OS/8 well enough.

Allison