The following message is a courtesy copy of an article that has been posted to bit.listserv.ibm-main,alt.folklore.computers as well.
[EMAIL PROTECTED] (John P. Baker) writes: > The Diagnose instruction has been documented in every Principles of > Operation manual issued for the S/360 architecture and for all > subsequent superseding architectures, and in every case, has > specifically stated that the functions performed by the Diagnose > instruction are not published, but may impact any and all aspects of > system operation, and if invoked by a user application built without > access to that unpublished documentation, may negatively impact the > proper functioning of the machine, requiring a Power On Reset and/or > the assistance of a Hardware Support Engineer to bring the system back > into proper working order. re: http://www.garlic.com/~lynn/2007v.html#21 It keeps getting uglier it also says that the operation of the diagnose may be model dependent. less than a month since it has been 40yrs since I was introduced to (virtual machine) cp67 system ... three people came out to the university from cambridge science center http://www.garlic.com/~lynn/subtopic.html#545tech to install cp67. while an undergraduate I did a lot of rework and optimization of the cp67 kernel. i had also done a lot of work on os/360 optimization ... for the workload at the univ. i gave a presentation at the aug68 share meeting in boston on some of that work ... part of that presentation http://www.garlic.com/~lynn/94.html#18 CP/67 & OS MFT14 one of the other things i did was develop a fast-path ccw translation for cms disk i/o when running in a virtual machine (original cms was implemented to be able to run on bare 360/40). I did this by defining a new channel program op-code for disk read/writes ... which acted as an immediate operation ... held the virtual SIO "busy" until the operation had completed and then presented CC=1, CSW STORED. I got some grief from the people at the science center since i was violating the 360 principles of operation. however, it was a useful performance improvement ... and so it was explained to me that I could "use" the diagnose instruction ... since the diagnose instruction was defined as being model dependent ... and for CP67 ... and artificial "virtual machine" 360 *model* could be defined where the diagnose instruction acted as defined by CP67 (w/o violating the principles of operation). misc. past posts mentioning model dependent diagnose instruction: http://www.garlic.com/~lynn/96.html#23 Old IBM's http://www.garlic.com/~lynn/2001b.html#32 z900 and Virtual Machine Theory http://www.garlic.com/~lynn/2002d.html#31 2 questions: diag 68 and calling convention http://www.garlic.com/~lynn/2002h.html#62 history of CMS http://www.garlic.com/~lynn/2003.html#60 MIDAS http://www.garlic.com/~lynn/2003k.html#52 dissassembled code http://www.garlic.com/~lynn/2003m.html#36 S/360 undocumented instructions? http://www.garlic.com/~lynn/2003p.html#9 virtual-machine theory http://www.garlic.com/~lynn/2004.html#8 virtual-machine theory http://www.garlic.com/~lynn/2004d.html#66 System/360 40 years old today http://www.garlic.com/~lynn/2004q.html#72 IUCV in VM/CMS http://www.garlic.com/~lynn/2005b.html#23 360 DIAGNOSE http://www.garlic.com/~lynn/2005j.html#54 Q ALLOC PAGE vs. CP Q ALLOC vs ESAMAP http://www.garlic.com/~lynn/2007f.html#33 Historical curiosity question http://www.garlic.com/~lynn/2007p.html#72 A question for the Wheelers - Diagnose instruction ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
