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Groups > alt.folklore.computers > #234470

Re: TSS arcana, Self-hosting and the 6502

From John Levine <johnl@taugh.com>
Newsgroups alt.folklore.computers
Subject Re: TSS arcana, Self-hosting and the 6502
Date 2026-03-31 00:58 +0000
Organization Taughannock Networks
Message-ID <10qf67n$2u8s$2@gal.iecc.com> (permalink)
References <10qehuo$2nu4m$1@dont-email.me> <10qenoj$2plle$1@dont-email.me>

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>For TSS/360 all address constants have to be copied and relocated each 
>time a program is loaded, and then it needs two memory fetches instead 
>of one to access the referenced address.

Sort of. TSS programs had CSECTs which were read-only and position independent
with one copy shared among all processes, and PSECTs which were read-write and
needed a separate copy per process which had pointers that were relocated when
loaded. The calling sequence had a pair of addresses for each routine, one to
the PSECT (the R-con) and one to the CSECT (the V-con). In retrospect it would
have made more sense to use one address for the PSECT and pick up the code
address from a known location in the PSECT. My guess is that they hoped there
would be routines with no static data so they could skip the R-con, but as far
as I know they never did that.

It is easy to write position independent 360 code since all references are
relative to base registers. You load a base register to point to wherever the
code is (BALR R,0 was the usual way) and off you go.  The routine would keep
a pointer to the PSECT in another register set up from the calling sequence,
so the routine can directly address both its code and its data without extra
instructions.  The calling sequence was slower than the OS/360 version, but
even the OS version was quite slow with register saves and save area chaining.

This isn't all that different from ELF shared libraries in Unix and linux, which
have position independent pages and the PLT and GOT with process-specific
pointers to the shared code.

Shameless plug: my book Linkers and Loaders explains this all in much more detail.

-- 
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly

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Thread

Re: Self-hosting and the 6502 Lev <thresh3@fastmail.com> - 2026-03-30 19:12 +0000
  Re: Self-hosting and the 6502 David Wade <g4ugm@dave.invalid> - 2026-03-30 21:01 +0100
    Re: Self-hosting and the 6502 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-03-30 21:02 +0000
    Re: Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-03-31 00:44 +0000
      Re: Self-hosting and the 6502 antispam@fricas.org (Waldek Hebisch) - 2026-03-31 19:46 +0000
        Re: TSS, Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-03-31 20:48 +0000
          Re: TSS, Self-hosting and the 6502 antispam@fricas.org (Waldek Hebisch) - 2026-04-01 23:23 +0000
            Re: TSS, Self-hosting and the 6502 cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-02 10:53 +0000
              Re: TSS, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-02 07:29 -0700
                Re: TSS, Self-hosting and the 6502 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-04-02 16:58 +0000
                Re: TSS, Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-02 20:34 +0000
                Re: TSS, Self-hosting and the 6502 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-04-02 20:53 +0000
        Re: Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-03-31 21:01 +0000
        Re: Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-03 16:53 -1000
          Re: Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-04 03:57 +0000
            Re: Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-04 07:37 -0700
              Re: Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-04-04 21:55 +0000
                Re: Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-04 15:48 -0700
                Re: ancient time sharingSelf-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-04-05 02:27 +0000
              Re: Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-04 22:03 +0000
                Re: Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-04 12:31 -1000
            Re: Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-04 07:40 -1000
            Re: Self-hosting and the 6502 Lars Poulsen <lars@beagle-ears.com> - 2026-04-04 13:44 -0700
              Re: Self-hosting and the 6502 (VSCP) ted@loft.tnolan.com (Ted Nolan <tednolan>) - 2026-04-05 20:23 +0000
        Re: Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-04 12:53 -1000
          Re: Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-04 23:44 +0000
            Re: Self-hosting and the 6502 David Wade <g4ugm@dave.invalid> - 2026-04-05 09:29 +0100
              Re: CMS, Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-04-05 19:22 +0000
                Re: CMS, Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-05 14:30 -1000
                Re: CMS, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-05 20:02 -0700
                history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-11 09:05 -0300
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Jeroen Belleman <jeroen@nospam.please> - 2026-09-11 16:49 +0200
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Andy Burns <usenet@andyburns.uk> - 2026-09-11 15:58 +0100
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-11 13:38 -0300
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Jeroen Belleman <jeroen@nospam.please> - 2026-09-11 19:41 +0200
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Andy Burns <usenet@andyburns.uk> - 2026-09-11 19:18 +0100
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Jeroen Belleman <jeroen@nospam.please> - 2026-09-11 21:27 +0200
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) scott@slp53.sl.home (Scott Lurndal) - 2026-09-11 21:13 +0000
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Lynn Wheeler <lynn@garlic.com> - 2026-09-12 14:47 -1000
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Lars Poulsen <lars@beagle-ears.com> - 2026-09-13 15:02 -0700
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-13 16:27 -0700
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Lynn Wheeler <lynn@garlic.com> - 2026-09-14 15:11 -1000
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-15 04:19 +0000
                Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) Lars Poulsen <lars@beagle-ears.com> - 2026-09-13 14:56 -0700
                Re: Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-15 04:10 +0000
                Re: Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) Lars Poulsen <lars@beagle-ears.com> - 2026-09-15 05:46 -0700
                Re: Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) Peter Flass <Peter@Iron-Spring.com> - 2026-09-15 07:51 -0700
                Re: Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-15 23:22 +0000
                Re: Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-15 23:13 +0000
                Re: Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) Jeroen Belleman <jeroen@nospam.please> - 2026-09-15 16:48 +0200
                Re: Computes at CERN (Re: history of ASCII and IBM ratfucking, and the VAX ) John Ames <commodorejohn@gmail.com> - 2026-09-15 08:19 -0700
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Lynn Wheeler <lynn@garlic.com> - 2026-09-12 14:13 -1000
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Lynn Wheeler <lynn@garlic.com> - 2026-09-12 14:12 -1000
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-13 14:02 -0300
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Andy Burns <usenet@andyburns.uk> - 2026-09-13 18:55 +0100
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Andy Burns <usenet@andyburns.uk> - 2026-09-13 19:03 +0100
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Andy Burns <usenet@andyburns.uk> - 2026-09-13 19:07 +0100
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-13 16:21 -0700
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Nuno Silva <nunojsilva@invalid.invalid> - 2026-09-14 00:37 +0100
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-13 20:56 -0700
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-09-14 04:12 +0000
                Re: history of ASCII and IBM ratfucking, and the VAX (was Re: CMS, Self-hosting and the 6502) Lynn Wheeler <lynn@garlic.com> - 2026-09-14 15:06 -1000
                Re: CMS, Self-hosting and the 6502 antispam@fricas.org (Waldek Hebisch) - 2026-04-06 01:42 +0000
                Re: CMS, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-05 20:05 -0700
                Re: CMS, Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-06 07:03 +0000
                Re: CMS, Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-05 22:19 -1000
                Re: CMS, Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-06 08:20 +0000
                Re: CMS, Self-hosting and the 6502 cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-06 12:03 +0000
                Re: CMS, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-06 07:30 -0700
                Re: CMS, Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-06 07:39 -1000
                Re: CMS, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-06 12:05 -0700
                Re: CMS, Self-hosting and the 6502 Lynn Wheeler <lynn@garlic.com> - 2026-04-06 17:41 -1000
                position-independent code (was Re: CMS, Self-hosting and the 6502) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-11 09:42 -0300
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Lynn Wheeler <lynn@garlic.com> - 2026-09-12 15:12 -1000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) John Levine <johnl@taugh.com> - 2026-09-13 01:57 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-12 21:14 -0700
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) legalize+jeeves@mail.xmission.com (Richard) - 2026-09-17 17:06 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) scott@slp53.sl.home (Scott Lurndal) - 2026-09-17 17:56 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) legalize+jeeves@mail.xmission.com (Richard) - 2026-09-18 14:08 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Nuno Silva <nunojsilva@invalid.invalid> - 2026-09-18 19:29 +0100
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) John Ames <commodorejohn@gmail.com> - 2026-09-18 12:00 -0700
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-09-18 20:35 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Andy Valencia <vandys@vsta.org> - 2026-09-17 11:32 -0700
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) James Dow Allen <user4353@newsgrouper.org.invalid> - 2026-09-13 07:31 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-13 07:45 -0700
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) John Levine <johnl@taugh.com> - 2026-09-13 16:50 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-13 16:18 -0700
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-15 04:21 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) scott@slp53.sl.home (Scott Lurndal) - 2026-09-15 14:33 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-15 07:37 -0700
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-15 23:35 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Lynn Wheeler <lynn@garlic.com> - 2026-09-14 14:41 -1000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) John Levine <johnl@taugh.com> - 2026-09-13 01:54 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-13 14:53 -0300
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) John Levine <johnl@taugh.com> - 2026-09-13 22:18 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Peter Flass <Peter@Iron-Spring.com> - 2026-09-13 16:24 -0700
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-14 01:51 +0000
                Re: position-independent code (was Re: CMS, Self-hosting and the 6502) scott@slp53.sl.home (Scott Lurndal) - 2026-09-14 14:53 +0000
                Re: CMS, Self-hosting and the 6502 antispam@fricas.org (Waldek Hebisch) - 2026-04-06 19:21 +0000
                Re: CMS, Self-hosting and the 6502 David Wade <g4ugm@dave.invalid> - 2026-04-06 21:25 +0100
    Re: Self-hosting and the 6502 antispam@fricas.org (Waldek Hebisch) - 2026-03-31 02:32 +0000
      Re: Self-hosting and the 6502 Bill Findlay <findlaybill@blueyonder.co.uk> - 2026-03-31 04:06 +0100
      Re: Self-hosting and the 6502 David Wade <g4ugm@dave.invalid> - 2026-03-31 08:52 +0100
        Re: Self-hosting and the 6502 Bill Findlay <findlaybill@blueyonder.co.uk> - 2026-03-31 18:07 +0100
  Re: Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-03-30 13:51 -0700
    Re: TSS arcana, Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-03-31 00:58 +0000
      Re: TSS arcana, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-03-31 07:35 -0700
        Re: TSS arcana, Self-hosting and the 6502 Bob Eager <news0009@eager.cx> - 2026-03-31 14:54 +0000
          Re: TSS arcana, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-03-31 13:01 -0700
      Re: TSS arcana, Self-hosting and the 6502 cross@spitfire.i.gajendra.net (Dan Cross) - 2026-03-31 22:14 +0000
        Re: TSS arcana, Self-hosting and the 6502 Bob Eager <news0009@eager.cx> - 2026-03-31 22:32 +0000
        Re: linkers, TSS arcana, Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-04-01 02:06 +0000
          Re: linkers, TSS arcana, Self-hosting and the 6502 Bob Eager <news0009@eager.cx> - 2026-04-01 09:53 +0000
            Re: linkers, TSS arcana, Self-hosting and the 6502 cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-01 16:07 +0000
              Re: linkers, TSS arcana, Self-hosting and the 6502 Bob Eager <news0009@eager.cx> - 2026-04-01 16:27 +0000
            Re: linkers, TSS arcana, Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-04-01 16:10 +0000
            Re: linkers, TSS arcana, Self-hosting and the 6502 Andy Walker <anw@cuboid.co.uk> - 2026-04-01 17:15 +0100
              Re: linkers, TSS arcana, Self-hosting and the 6502 Bob Eager <news0009@eager.cx> - 2026-04-01 16:28 +0000
                Re: linkers, TSS arcana, Self-hosting and the 6502 scott@slp53.sl.home (Scott Lurndal) - 2026-04-01 16:48 +0000
                Re: linkers, TSS arcana, Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-04-01 17:44 +0000
                Re: linkers, TSS arcana, Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-04-01 14:21 -0700
              Re: linkers, TSS arcana, Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-01 20:40 +0000
                Re: linkers, TSS arcana, Self-hosting and the 6502 scott@slp53.sl.home (Scott Lurndal) - 2026-04-01 22:02 +0000
              Re: linkers, TSS arcana, Self-hosting and the 6502 Andy Walker <anw@cuboid.co.uk> - 2026-04-02 15:28 +0100
                Re: linkers, TSS arcana, Self-hosting and the 6502 scott@slp53.sl.home (Scott Lurndal) - 2026-04-02 15:36 +0000
                Re: linkers, TSS arcana, Self-hosting and the 6502 Andy Walker <anw@cuboid.co.uk> - 2026-04-02 17:15 +0100
                Re: linkers, TSS arcana, Self-hosting and the 6502 cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-02 16:44 +0000
  Re: Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-03-30 21:30 +0000
    Re: Self-hosting and the 6502 David Wade <g4ugm@dave.invalid> - 2026-03-30 23:28 +0100
      Re: Self-hosting and the 6502 Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-03-30 23:36 +0000
        Re: Self-hosting and the 6502 John Ames <commodorejohn@gmail.com> - 2026-03-31 07:46 -0700
          Re: Self-hosting and the 6502 snipeco.2@gmail.com (Sn!pe) - 2026-03-31 15:54 +0100
          Re: Self-hosting and the 6502 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-03-31 19:03 +0000
      Re: VM history, was Self-hosting and the 6502 John Levine <johnl@taugh.com> - 2026-03-31 01:04 +0000
        Re: VM history, was Self-hosting and the 6502 cross@spitfire.i.gajendra.net (Dan Cross) - 2026-03-31 22:17 +0000
    Re: Self-hosting and the 6502 Peter Flass <Peter@Iron-Spring.com> - 2026-03-30 15:36 -0700
      Re: Self-hosting and the 6502 cross@spitfire.i.gajendra.net (Dan Cross) - 2026-03-31 22:19 +0000

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