diff --git a/mps/code/ssixi3.c b/mps/code/ssixi3.c
deleted file mode 100644
index a922cabc5a6..00000000000
--- a/mps/code/ssixi3.c
+++ /dev/null
@@ -1,111 +0,0 @@
-/* ssixi3.c: UNIX/INTEL STACK SCANNING
- *
- * $Id$
- * Copyright (c) 2001 Ravenbrook Limited. See end of file for license.
- *
- * This scans the stack and fixes the registers which may contain
- * roots. See
- *
- * This code was originally developed and tested on Linux, and then
- * copied to the FreeBSD and Darwin (OS X) operating systems where it
- * also seems to work. Note that on FreeBSD and Darwin it has not
- * been indepently verified with respect to any ABI documentation.
- *
- * This code is common to more than one Unix implementation on
- * Intel hardware (but is not portable Unix code).
- *
- * The registers edi, esi, ebx are the registers defined to be preserved
- * across function calls and therefore may contain roots.
- * These are pushed on the stack for scanning.
- *
- * SOURCES
- *
- * .source.callees.saves: Set of callee-saved registers taken from
- * CALL_USED_REGISTERS in /config/i386/i386.h.
- * ebp added to the list because gcc now doesn't always use it as
- * a frame pointer so it could contain a root.
- *
- * ASSUMPTIONS
- *
- * .assume.align: The stack pointer is assumed to be aligned on a word
- * boundary.
- *
- * .assume.asm.stack: The compiler must not do wacky things with the
- * stack pointer around a call since we need to ensure that the
- * callee-save regs are visible during TraceScanArea.
- *
- * .assume.asm.order: The volatile modifier should prevent movement
- * of code, which might break .assume.asm.stack.
- *
- */
-
-
-#include "mpm.h"
-
-SRCID(ssixi3, "$Id$");
-
-
-/* .assume.asm.order */
-#define ASMV(x) __asm__ volatile (x)
-
-
-Res StackScan(ScanState ss, Word *stackCold,
- mps_area_scan_t scan_area,
- void *closure)
-{
- Word calleeSaveRegs[4];
-
- /* .assume.asm.stack */
- /* Store the callee save registers on the stack so they get scanned
- * as they may contain roots.
- */
- ASMV("mov %%ebx, %0" : "=m" (calleeSaveRegs[0]));
- ASMV("mov %%esi, %0" : "=m" (calleeSaveRegs[1]));
- ASMV("mov %%edi, %0" : "=m" (calleeSaveRegs[2]));
- ASMV("mov %%ebp, %0" : "=m" (calleeSaveRegs[3]));
-
- return StackScanInner(ss, stackCold, calleeSaveRegs, NELEMS(calleeSaveRegs),
- scan_area, closure);
-}
-
-
-/* C. COPYRIGHT AND LICENSE
- *
- * Copyright (C) 2001-2002 Ravenbrook Limited .
- * All rights reserved. This is an open source license. Contact
- * Ravenbrook for commercial licensing options.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * 3. Redistributions in any form must be accompanied by information on how
- * to obtain complete source code for this software and any accompanying
- * software that uses this software. The source code must either be
- * included in the distribution or be available for no more than the cost
- * of distribution plus a nominal fee, and must be freely redistributable
- * under reasonable conditions. For an executable file, complete source
- * code means the source code for all modules it contains. It does not
- * include source code for modules or files that typically accompany the
- * major components of the operating system on which the executable file
- * runs.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
- * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
- * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
- * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
diff --git a/mps/code/ssixi6.c b/mps/code/ssixi6.c
deleted file mode 100644
index 2d70d62697c..00000000000
--- a/mps/code/ssixi6.c
+++ /dev/null
@@ -1,111 +0,0 @@
-/* ssixi6.c: UNIX/x64 STACK SCANNING
- *
- * $Id$
- * Copyright (c) 2001-2014 Ravenbrook Limited. See end of file for license.
- *
- * This scans the stack and fixes the registers which may contain
- * roots. See
- *
- * This code was branched from ssixi3.c (32-bit Intel) initially for the
- * port to XCI6LL (Mac OS X on x86_64 with Clang).
- *
- * This code is common to more than one Unix implementation on
- * Intel hardware (but is not portable Unix code). According to Wikipedia,
- * all the non-Windows platforms use the System V AMD64 ABI. See
- * .sources.callees.saves.
- *
- * SOURCES
- *
- * .sources.callees.saves:
- * "Registers %rbp, %rbx and %r12 through %r15 "belong" to the calling
- * function and the called function is required to preserve their values.
- * In other words, a called function must preserve these registers’ values
- * for its caller." -- System V AMD64 ABI
- *
- *
- * ASSUMPTIONS
- *
- * .assume.align: The stack pointer is assumed to be aligned on a word
- * boundary.
- *
- * .assume.asm.stack: The compiler must not do wacky things with the
- * stack pointer around a call since we need to ensure that the
- * callee-save regs are visible during TraceScanArea.
- *
- * .assume.asm.order: The volatile modifier should prevent movement
- * of code, which might break .assume.asm.stack.
- *
- */
-
-
-#include "mpm.h"
-
-SRCID(ssixi6, "$Id$");
-
-
-/* .assume.asm.order */
-#define ASMV(x) __asm__ volatile (x)
-
-
-Res StackScan(ScanState ss, Word *stackCold,
- mps_area_scan_t scan_area,
- void *closure)
-{
- Word calleeSaveRegs[6];
-
- /* .assume.asm.stack */
- /* Store the callee save registers on the stack so they get scanned
- * as they may contain roots.
- */
- ASMV("mov %%rbp, %0" : "=m" (calleeSaveRegs[0]));
- ASMV("mov %%rbx, %0" : "=m" (calleeSaveRegs[1]));
- ASMV("mov %%r12, %0" : "=m" (calleeSaveRegs[2]));
- ASMV("mov %%r13, %0" : "=m" (calleeSaveRegs[3]));
- ASMV("mov %%r14, %0" : "=m" (calleeSaveRegs[4]));
- ASMV("mov %%r15, %0" : "=m" (calleeSaveRegs[5]));
-
- return StackScanInner(ss, stackCold, calleeSaveRegs, NELEMS(calleeSaveRegs),
- scan_area, closure);
-}
-
-
-/* C. COPYRIGHT AND LICENSE
- *
- * Copyright (C) 2001-2014 Ravenbrook Limited .
- * All rights reserved. This is an open source license. Contact
- * Ravenbrook for commercial licensing options.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * 3. Redistributions in any form must be accompanied by information on how
- * to obtain complete source code for this software and any accompanying
- * software that uses this software. The source code must either be
- * included in the distribution or be available for no more than the cost
- * of distribution plus a nominal fee, and must be freely redistributable
- * under reasonable conditions. For an executable file, complete source
- * code means the source code for all modules it contains. It does not
- * include source code for modules or files that typically accompany the
- * major components of the operating system on which the executable file
- * runs.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
- * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
- * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
- * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */