It's been ages since I debugged a user program in CMS, and I'm stumbling over things I used to remember, so I have a few questions for anyone who's got something to offer.

I have a program that has multiple SD entries, and the addresses start at X'020000' and go up. The programs were separately compiled so the displacements shown in the listings are for that particular routine->text deck->module. That is ... a module that loads at 275F0, and the instruction I want to look at is X'0A' (10 decimal) bytes in, I want to X 275FA 8, to see the code in memory, -OR- if I have defined the ORIGIN 02000, then I have to remember to really use X 075FA 8.

I can DEFINE addresses to stop at, and use BREAK to stop execution to look at the GPR and X or DUMP memory, and GO from there. These I usually remember what I have set ORIGIN to, so the BREAKs stop at the right instruction.

What I seem to keep tripping over is the use of ORIGIN. I know if it gets set to say, 020000, that value is added to the addresses I use in DEFINEs, or in X or DUMP commands. This is all well and good, until I forget, while looking at a listing to which I have written down the absolute address (the sum of the SD entry and the listing's displacement) to a command or data area. Then it becomes a game of addition and subtraction in hexadecimal, which isn't fun, yet.

SO ... when you are debugging, do you actually make use of ORIGIN, or not?
At X'000000' or X'020000' or ...?
Do you change it as you work through your program, or leave it alone?
If you change it, do you have it set to the SD value of the routine you are examining?
Or should I bias my paper calculations, as I refer to my listings?

Thanks for your help.

?... Mark S.

On Tue, Feb 7, 2023 at 02:42 AM, Dave Wade wrote:

If your work is on OS SVCs and you are familiar with OS please note that the OS emulation in CMS is based on OS/MVT release 21.8.

I guess I'm going to need to start collecting MVT books from Bitsavers, and the like.

Thanks!

?... Mark S.

On Mon, Feb 6, 2023 at 09:28 PM, Mark Waterbury wrote:

The CMS OS simulation is fairly well described in that VM/370 Release 6 Vol 2 Mar 1979? PLM ... :-)

One of several books/PDFs I have cracked open at this point.

Thanks!

?... Mark S.

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Hi, Mark,

The CMS OS simulation is fairly well described in that VM/370 Release 6 Vol 2 Mar 1979? PLM ... :-)

I hope that helps,

Mark

On Sun, Feb 5, 2023 at 06:08 PM, Mark Waterbury wrote:

There are overlapping SVC numbers between CP and CMS, because the CP ones only matter when you are running inside CP ... some DMKxxx modules;? CMS is running in a virtual machine (the DMSxxx modules) and has its own "set" of SVC numbers.? ?CMS also supports OS simulation so many SVC numbers come from OS/360 MVT ... to allow those OS compilers etc. to run under CMS.? ?

If you "SET DOS ON" in CMS, that swaps in a different SVC table, to emulate DOS/VS SVC numbers.

Mark,

Thanks for the information. I was not aware of the overlap. I was aware of OS vs DOS for some stuff, but now I know about SVCs.

My focus is on the OS simulation, since the assembler code I am working with is supposed to support OS(MVS) and CMS conventions.

?... Mark S.

Mark,

See:
? ?

Note the last three manuals on that page ... Vol. 1 is for CP, Vol. 2 is for CMS ... Vol. 3 is for RSCS etc.

SVC 202 and 203 are for CMS ... and are defined or described on page 2-7 of that Vol. 2 manual:

?

There are overlapping SVC numbers between CP and CMS, because the CP ones only matter when you are running inside CP ... some DMKxxx modules;? CMS is running in a virtual machine (the DMSxxx modules) and has its own "set" of SVC numbers.? ?CMS also supports OS simulation so many SVC numbers come from OS/360 MVT ... to allow those OS compilers etc. to run under CMS.? ?

If you "SET DOS ON" in CMS, that swaps in a different SVC table, to emulate DOS/VS SVC numbers.

Hope that helps,

Mark S. Waterbury

On Sun, Feb 5, 2023 at 05:16 PM, Bob Polmanter wrote:

SVC 6 is LINK

That's the one I was looking for! So I need to go digging into the OS/VS* manuals. Oh bother. Now to find the proper manual "over there."

Page 258 backs up your recollection.

CMS supports selected SVC calls generated by as and DOS/VS macros, by
simulating the effect of these macro calls. DMSITS is the initial SVC
interrupt handler. If the SET DOS command has been issued, a flag in
NUCON will indicate that DOS/VS macro simulation is to be used. Control
is then passed to DMSITS. Otherwise, as macro simulation is assumed and
DMSITS passes control to the appropriate OS simulation routine.

?... Mark S.

Mark,

To the best of my recollection, all SVCs issued in CMS other than those in the 200s? (e.g., 202, 203), are used by OS simulation.? Thus SVC 8 is from an OS LOAD macro.? SVC 10 is GETMAIN/FREEMAIN.? SVC 6 is LINK.? Thus those are documented in VS1 or VS2 documentation of the period.? There are several more.

The SVC 8 documented posted here just a couple of messages ago is for CP's use of SVC 8.? That is NOT the same as what a CMS user will encounter, so disregard the documentation in that post.

Regards,
Bob

On Sun, Feb 5, 2023 at 03:58 PM, Tony Harminc wrote:

Tony,

Thanks. I was trying to stay within the VM/370 environment, but I will also look at these.

?... Mark S.

On Sun, Feb 5, 2023 at 04:25 PM, Joe Monk wrote:

Beginning at page 257.

Thank you Joe. I might back up a page ;-)

?... Mark S.

On Sun, Feb 5, 2023 at 03:48 PM, Dave Wade wrote:

As SVC 8 is a OS/MFT call it won’t be documented.

Dave,

Thanks for the pointer to GC20-1807-7_VM370_System_Programmers_Guide_Rel_6_4-81.pdf, Seems to start at p. 256.

This is where I got the list from SY20-0886-1_VM370_Rel_6_Vol_1_Mar79.pdf,? Figure 4, page 1-17, the SVC Interrupt "box" shows (bolding by me) ...

If PROBLEM MODE
? And ADSTOP SVC, simulate 'ADSTOP' to
virtual machine
? And an SVC 76, verify the parameters and
call DMKVER to build the error record. (A)
? And virtual machine IS In extended
mode and/or Page 0 is not in storage,
reflect interrupt to virtual machine
? Otherwise, fetch Page 0, move CP PSW
to virtual SVCOPSW, and move SVCNPSW
to the CP PSW
? If supervisor mode, run user-LPSW

If SVC 0 (Impossible condition or fatal error),
dump the machine

If SVC 8 (Link Request), (B)
pass control from one module to another

If SVC 12 (Return Request),
return control to calling module

If SVC 16, release Save Area (C)

If SVC 20, get next save area for (D)
calling module

If SVC 24, switch processing to
main processor

So ... that is why I gave the original list above.

?... Mark S.

On Sun, 5 Feb 2023 at 16:11, Mark A. Stevens via groups.io
<marXtevens@...> wrote:

I've run into SVC 8, 202 and 203, and I'd like to know if there is a manual that contains all of them, and what they do.

SY20-0886-1_VM370_Rel_6_Vol_1_Mar79.pdf covers 0, 8, 12, 16, 20, & 24, but not 202 or 203.

The modern zVM docs explain a lot of what SVC 202 does, even though
they deprecate it. Obviously VM/370+mods doesn't implement everything,
but it's good background reading.




(The above two docs have a huge amount of overlap. Probably the first
one is best to get an understanding.)

Tony H.

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I've run into SVC 8, 202 and 203, and I'd like to know if there is a manual that contains all of them, and what they do.

covers 0, 8, 12, 16, 20, & 24, but not 202 or 203.

... Mark S.

On Fri, May 27, 2022 at 01:20 PM, Dave Wade wrote:

f you want output on the real printer change line 6 to

?

“SPOOL ?PRT SYSTEM CLASS A”

?

And you will have to then start the printer from say OPERATOR

?

CP START? F CLASS A

?

Dave

If you are up to it, you can log on to OPERATOR, or probably a better bet is to log on to AUTOLOG.

Then in the PROFILE EXEC add the lines Dave mentions, That way the printer will be up and running every time you IPL VM.

?... Mark S.