This group is for all folks running the original IBM VM/370 Release 6 operating system (or later (e.g. VMTCE (Community Edition)) on Hercules. Like the other early IBM operating systems this version has always been in the public domain and so can be freely distributed. The base version as supplied by IBM is lacking in many facilities. IBM solved this by providing additional extension products which were licensed and so are not available. There are however many user enhancements available which can be installed. In addition, in order to get users up and running quickly updated "releases" of VM/370 included the most popular updates are available for download, so novices can start to learn VM without having to delve into the system internals. It is intended that this wiki will provide information on the base release and these updates.
The available versions are here :-
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Re: memset help
<adrian@...> wrote: If you're considering cross-compiling on a non S/370 architecture machine (rather than, say, a modern IBM zArch box), you'll need to consider the parsing and
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Tony Harminc
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#1038
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Re: memset help
This one is clearly zeroing storage - not copying data. R3 is the "from" length field, and it's zero, so the MVCL is padding only (and that pad byte is zero). And the "from" address in R2 is
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Tony Harminc
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#1037
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Re: Register Add - Quick Question
<adrian@...> wrote: A couple of points... In modern (i.e. z) architectural variants, there are new immediate instructions that may help with this. Notably there is AHI (Add Halfword
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Tony Harminc
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#1036
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Re: memset help
Mark L. Gaubatz wrote: It somehow failed to dawn on me that the MVCs in URMON were going to/from zero page and therefore there was no possibility of some of the code being repeated in a loop to move a
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Peter Coghlan
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#1035
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Re: memset help
In this particular case, it is the output of a disassembler. It's what we have to cope with when we don't have the source code to look at. Regards, Peter Coghlan.
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Peter Coghlan
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#1034
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Re: memset help
For interest. Is that machine generated or hand crafted? If the latter must have been very error prone and expensive!
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adriansutherland67
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#1033
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Re: memset help
You have to be careful in analysis. The MVC sequences are intentionally moving and modifying parts of Page Zero. This is probably related to swapping of the current running user on MUSIC, or status
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Mark L. Gaubatz
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#1032
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Re: memset help
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Dave Wade
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#1031
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Re: memset help
<keanu> Whoa. </keanu> I sure wouldn't have wanted to be you in high school, Steve. ;) -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Dave McGuire
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#1030
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Re: memset help
Oh dear. I have had the problem in the past of my e-mails being picked up by spam filters and so has my brother. I think in our case it was a case of the Scunthorpe problem
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Steven Fosdick
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#1029
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Re: Register Add - Quick Question
Peter ... You have taught me what F meant!
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adriansutherland67
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#1028
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Re: Register Add - Quick Question
You are gentlemen ... thank you! It is for a 24 bit address. A
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adriansutherland67
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#1027
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Re: Register Add - Quick Question
This form of LA: LA Rx,D2(Rx) is only good to add up to 4095 to a register. Past that you have to use other instructions. And as Peter noted, the left 8 bits will be zeroed in AM24. Joe wrote:
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Joe Monk
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#1026
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Re: Register Add - Quick Question
Mostly! LA works as long as the answer fits in 24 bits so it's no good for adding 8 to a negative value in R1 for example. An alternative solution is: A R1,=F'8' If memory is really tight, you could
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Peter Coghlan
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#1025
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Re: Register Add - Quick Question
Yes! LA R1,8(R1) Joe adrian@...> wrote:
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Joe Monk
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#1024
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Register Add - Quick Question
Is there a better way than this to add 8 to R1? LA? ? R0,8 AR? ? R1,R0? ? ? ? ? Add 8 to R1 Thanks A
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adriansutherland67
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#1023
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Re: memset help
Slowly learning - I think I can do USING and DROP and use MACROs as well ... includes/copybooks A
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adriansutherland67
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#1022
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Re: memset help
Exactly - however we don't really care about the backend optimisations (after all we use Hercules which has completely different timing characteristics), but we do the front end / C ones; for example
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adriansutherland67
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#1021
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Re: memset help
I recovered it ... the real issue is that it was work in progress A
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adriansutherland67
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#1020
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Re: memset help
Perhaps ... and 16mb is not very very tiny ... I think it is the optimisers that will cause dramas!
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adriansutherland67
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#1019
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