On 05/04/2026 00:44, Lawrence D?Oliveiro wrote:
I wonder how many people at DEC worked on TOPS-10 ... remember, they
were able to provide true multiuser support from the get-go, which CMS
could not.
No but CMS is still in use today, and it still doesn't provide true
multi user support whatever that is
No matter what it is, it would make no sense since it only runs under
VM which provides quite a lot of multi-user support.
I would also note that any VM system that can run CMS can also run
several flavors of linux, all at the same time, if that's what you
want.
John Levine <johnl@taugh.com> writes:
No matter what it is, it would make no sense since it only runs under
VM which provides quite a lot of multi-user support.
I would also note that any VM system that can run CMS can also run
several flavors of linux, all at the same time, if that's what you
want.
"Future System" overlapped adding virtual memory to all 370s, FS was
totally different than 370 and was going to completely replace it,
internal politics during FS was killing off 370 projects and lack of new
370 during FS period is credited with giving clone 370 makers their
market foothold.
when "FS" finally imploded, there was mad rush to get stuff back into
370 product pipeline, including kicking off quick&dirty 3033&3081 in parallel.
1974, CERN presented comparison of VM370/CMS and MVS/TSO at SHARE ...
inside IBM the report was classified "IBM Confidential - Restricted" "on
need to know" only (not wanting internal employees see the
comparison). How much better VM370/CMS looked likely was major factor in
the head of POK (high-end 370s) convincing corporate to kill the
VM370/CMS product, shutdown the development group and transfer all the
people to POK for MVS/XA (Endicott lab eventually manages to acquire the VM370/CMS product mission, but had to recreate a development group from scratch).
John Levine <johnl@taugh.com> wrote:
According to David Wade <g4ugm@dave.invalid>:
On 05/04/2026 00:44, Lawrence D?Oliveiro wrote:
I wonder how many people at DEC worked on TOPS-10 ... remember, they
were able to provide true multiuser support from the get-go, which CMS >>>> could not.
No but CMS is still in use today, and it still doesn't provide true
multi user support whatever that is
No matter what it is, it would make no sense since it only runs under VM which provides
quite a lot of multi-user support.
I would also note that any VM system that can run CMS can also run several flavors of linux,
all at the same time, if that's what you want.
VM6 runs in 370 mode and runs CMS. IIUC Linux needs at least s390 mode
so can not run under VM6.
On 4/5/26 18:42, Waldek Hebisch wrote:
VM6 runs in 370 mode and runs CMS. IIUC Linux needs at least s390
mode so can not run under VM6.
One of the colleges, probably Marist, had an unofficial version of
Linux running on a 370. I understand GCC wanted a PC-relative branch instruction, so they had to code around that.
Did it really take that many decades for IBM to understand the concept
of position-independent code?
Lawrence D?Oliveiro <ldo@nz.invalid> writes:
Did it really take that many decades for IBM to understand the
concept of position-independent code?
TSS/360 supported position independent code .... could have same
shared segments across different virtual address spaces at different
address locations.
OS/360 languages generated executable with "relocatable" addresses
and loader, loading the executable images when loaded, the relocable addresses were updated for the ("fix") loaded address locations (aka "relocatable" until loaded for execution).
Did it really take that many decades for IBM to understand the concept
of position-independent code?
TSS/360 supported position independent code .... could have same shared >segments across different virtual address spaces at different address >locations.
On Sun, 5 Apr 2026 20:05:11 -0700, Peter Flass wrote:
On 4/5/26 18:42, Waldek Hebisch wrote:
VM6 runs in 370 mode and runs CMS. IIUC Linux needs at least s390
mode so can not run under VM6.
One of the colleges, probably Marist, had an unofficial version of
Linux running on a 370. I understand GCC wanted a PC-relative branch
instruction, so they had to code around that.
Did it really take that many decades for IBM to understand the concept
of position-independent code?
360 was all position-independent. In theory there were no absolute
addresses, everything was base-displacement. Change the base register
and Bob's your uncle. Unfortunately there were a couple of gotchas,
address constants being the worst. Also the small range of addresses available from a single base became limiting as programs got larger.
W/o location independence and requiring executable image to be otherwise preloaded to have address constants to be modified to their executing position ... would have required every executing program image to have
unique address across the whole system
certain executables to be concurrently mapped into the same address
space).
Peter Flass <Peter@iron-spring.com> wrote:
On 4/5/26 18:42, Waldek Hebisch wrote:
John Levine <johnl@taugh.com> wrote:
According to David Wade <g4ugm@dave.invalid>:
On 05/04/2026 00:44, Lawrence D?Oliveiro wrote:
I wonder how many people at DEC worked on TOPS-10 ... remember, they >>>>>> were able to provide true multiuser support from the get-go, which CMS >>>>>> could not.
No but CMS is still in use today, and it still doesn't provide true
multi user support whatever that is
No matter what it is, it would make no sense since it only runs under VM which provides
quite a lot of multi-user support.
I would also note that any VM system that can run CMS can also run several flavors of linux,
all at the same time, if that's what you want.
VM6 runs in 370 mode and runs CMS. IIUC Linux needs at least s390 mode
so can not run under VM6.
One of the colleges, probably Marist, had an unofficial version of Linux
running on a 370. I understand GCC wanted a PC-relative branch
instruction, so they had to code around that.
AFAICS there is more to this. There was a version of GCC targeting
370, so in a sense that was handled. But IIUC GCC for 370 emited
assembler that Paul Edwards used, which was similar or maybe
identical to assembler for some version of MVS. However, for
me neither MVS assembler (that is version that I had) nor
binutils were able to handle assembler output from GCC.
Beside GCC, AFAICS there is substantial difference in s390 and
370 system instructions and data structures. So one would have
to rework low level machine specific support.
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