Starting with 1.47, changes marked with SYSLINUX/PXELINUX/ISOLINUX
apply to that specific program only; other changes apply to both.

Changes in 1.66:
* MEMDISK: Make compile with newer versions of gcc.

Changes in 1.65:
* ISOLINUX: Support booting disk image files (to boot DOS or
  other non-Linux operating systems), *IF* the BIOS works
  correctly; unfortunately many BIOSes apparently don't.
* Support Linux boot protocol version 2.03 (explicitly
  specify the initrd address limit.)
* Handle small "pseudo-kernels"; images that use the Linux
  kernel boot protocols but are less than 64K in size.
* MEMDISK: New subsystem; this is a driver which allows
  legacy OSes to boot using an in-memory simulated disk.
  See memdisk/memdisk.doc for more info.
* PXELINUX, ISOLINUX: Correctly handle files larger than 65535
  blocks (32 MB for PXELINUX, 128 MB for ISOLINUX.)
* PXELINUX: Make a best-effort attempt at freeing all memory
  claimed.  From the looks of it, it will fail on most PXE
  stacks.

Changes in 1.64:
* Limited support for hardware flow control when using a
  serial port console.
* Support specifying the serial port I/O address explicitly.
* Make DOS installer hopefully behave more nicely when used on
  recent Windows versions.
* Fix returning to text mode when a font has been specified.
* Attempt to detect missing serial port hardware and disable
  the serial port if there is nothing there.

Changes in 1.63:
* Make the ppmtolss16 program handle color conversion more
  correctly.
* Clean up "make install" target, honour INSTALLROOT if it
  exists.
* SYSLINUX: Fix stack-smash bug identified by Steffen
  Winterfeldt.
* Hopefully fix return-to-text-mode on some graphics cards.
* ISOLINUX: Bug workaround for Award BIOS 4.51, and perhaps
  other buggy BIOSes as well.

Changes in 1.62:
* PXELINUX: Allow the DHCP server to override the
  configuration file name and pathname prefix, using
  "site-specific" DHCP options.
* PXELINUX: Documentation fixes.
* PXELINUX: Fix the "ipappend" option; the last two values
  were reversed vs. what the kernel expected.
* Introduce a way to return to text mode once we are already
  in graphics mode.  This may be useful for F-key help
  screens.
* Fix several bugs in the way return to text mode was handled.

Changes in 1.61:
* ISOLINUX: Support full pathname searches.  Max length for a
  pathname is 255 characters.  As a result, only 64 "label"
  statements are supported in ISOLINUX.
* PXELINUX: Max filename length extended to 63 characters.

Changes in 1.60:
* Add support for graphical splash screens.
* Add mode control characters, which allows you to control
  message display output depending on output mode (text,
  graphics, or serial port.)
* ISOLINUX: New program, which boots Linux from a CD-ROM
  without using floppy emulation mode.  See isolinux.doc for
  more details.
* PXELINUX: Don't search for boot sector file types, since
  they don't work anyway.
* SYSLINUX: Document the LOCK command for Win9x, and the error
  dialog box for WinNT/2K.

Changes in 1.54:
* PXELINUX: Fix code for finding !PXE from PXENV+.  This was
  due to a spec bug; match the most recent spec since that
  seems to be what implementations actually do.
* SYSLINUX: Add some smarts to the boot sector, which
  hopefully should reduce the number of systems which require 
  stupid mode ("syslinux -s").
* PXELINUX: Document further some of the pathologies with old
  PXE stacks.
* When specifying a "default" command line, no longer
  automatically appent "auto".  See the "DEFAULT" command in
  syslinux.doc for more information.
* PXELINUX: Clean up the allocation of local socket numbers.

Changes in 1.53:
* PXELINUX: Rename pxelinux.bin to pxelinux.0, to match what
  most PXE servers seem to expect.
* PXELINUX: Update the DHCP/boot server setup documentation.
* PXELINUX: Support new "localboot" option for "label"
  sections.
* PXELINUX: More robust parsing of DHCP/boot server packets.
* PXELINUX: Include a small utility program "gethostip" to
  compute hexadecimal IP addresses.

Changes in 1.52:
* PXELINUX: Fix bugs introduced by new A20 code.  (SYSLINUX
  has also been changed for code consistency reasons, but I'm
  pretty sure the changes are don't care on SYSLINUX.)
* Documentation updates.
* PXELINUX: Add "ipappend" option to generate an ip= option to
  the kernel.

Changes in 1.51:
* PXELINUX: Not all PXE stacks fill in the IP address for a
  type 3 cached info query.  Use a type 2 cached info query
  for this information (only.)
* Yet another attempt at A20 coding.  Now support BIOS call
  15:2401 as well, and handle machines which always have A20
  on separately.
* Support memory detection using INT 15h, AX=0E820h.  BIOS
  manufacturers have apparently gotten sloppy about keeping
  INT 15h, AX=0E801h working properly.
* Don't issue <CR><LF> onto the serial port when we're doing
  screen wraparound.

Changes in 1.50:
* Yet another A20-code update.  It seems some "legacy-free"
  machines and embedded gear simply don't have a KBC to talk
  to, and that waiting for one will wait forever.  Sigh.

Changes in 1.49:
* SYSLINUX: Implement a hack for BIOS drivers which hog significant
  chunks of low memory during boot.  (Note: PXELINUX already
  had this modification.  SYSLINUX does still require that the
  low 512K is available; PXELINUX requires 384K.  Machines
  with a physical memory hole in the low 640K cannot boot
  Linux no matter what.)  Depending what the reason is for the
  memory hole, a new kernel (2.4.0-test3-pre3 or later) may be
  required.
* SYSLINUX: Default installer binary now compiled against
  glibc 2.1.  If this is inappropriate for your system and you
  still want to use the offical version of SYSLINUX, please
  follow the instructions in "distrib.doc" to rebuild the
  installer.
* SYSLINUX: Linux installer program now supports -o <offset>
  option which does a loopback mount with the
  -o loop,offset=<> option.  Useful to run SYSLINUX on an
  individual partition of a whole-harddisk image.
* Include the source code to a Master Boot Record (MBR)
  functionally equivalent to the one installed DOS except it
  includes EBIOS support, and should be resistant to geometry
  changes.  The MBR code is public domain.
* PXELINUX: Fix "double p" bug: if the tftp prefix was null,
  all filenames would get a "p" preprended, e.g.
  "ppxelinux.cfg" and "pvmlinux".

Changes in 1.48:
* PXELINUX: Workaround for PXE ROMs based on the Intel PXE PDK
  3.0 build 071 and earlier: missing !PXE structure pointer.
* PXELINUX: Handle larger BOOTP/DHCP packages.
* PXELINUX: The command line passing was broken; fix.
* PXELINUX: Make COMBOOT images work.
* PXELINUX: Documentation on how to make booting work using
  the PDK 3.0-derived clients, which aren't so generous as to
  allow booting with only "PXEClient" specified.

Changes in 1.47:
* PXELINUX: RFC 1123 states that a TFTP implementation MUST
  use adaptive timeout, "at least an exponential backoff of
          retransmission timeout is necessary."  Implement a very
  simple exponential backoff for retransmits.
* PXELINUX: Updated documentation, including pointer to new
  TFTP server.
* PXELINUX: When sending ERROR due to bad OACK, use the proper
  destination port number (why are TFTP port numbers so odd?)
* PXELINUX: If the boot dies in the middle somewhere,
  eventually give up and reset the machine (unattended
  operation.)

Changes in 1.46:
* New program PXELINUX to do network booting using a
  PXE-compliant (Pre-Execution Environment) network booting
  PROM.  See pxelinux.doc for details.

Changes in 1.45:
* Serial console support.  See syslinux.doc for details.

Changes in 1.44:
* Change HIGHMEM_MAX to 38000000h to (hopefully) avoid the
  kernel stepping on it; 3f000000h was apparently a higher
  limit than the kernel used!

Changes in 1.43:
* Add sys2ansi.pl script to display the contents of a
  colorized SYSLINUX file.
* Changed the io_delay once again, after a report that the
  old delay port causes hangs on some systems.

Changes in 1.42:
* Frob the "fast A20 gate" port as well as the keyboard
  controller; will this help systems with problems?
* Be even more paranoid about A20, unfortunately even this
  seems to be not paranoid enough... what I don't understand
  is that if there is hardware out there *this broken*, how
  can it run Linux at all?  Report an error message rather
  than hang forever if A20 is stuck.
* Include some intermediate files in the distribution, plus
  provide a "make installer" target for distributors to relink
  the install programs only.  I would prefer the syslinux boot
  loader proper to be "binary clean" for debuggablity -- use
  "make clean ; make installer" to rebuild the installers only.

Changes in 1.41:
* Don't get confused by directories, volume labels, or VFAT
  long names.
* Use INT 15h, AX=0E801h to query memory size before trying
  INT 15h, AH=88h.  This not only provides more headroom
  between the kernel and the initrd on large-memory machines,
  but it appears some recent BIOSes actually have started
  returning garbage for the AH=88h (older) call.
* Trust high memory beyond the 15 MB mark if the user has
  specified it, or if obtained with INT 15h, AH=0E801h (with
  no memory holes above 1 MB.)

Changes in 1.40:
* Increase A20M delay and put in a test to avoid problems on
  certain IBM Thinkpads (thanks to Donnie Barnes of RedHat
  for vital info on this one.)
* Support COMBOOT style boot command images.
* Support chain loading (foreign operating systems, e.g. DOS).
* Include a new "copybs" DOS utility to copy a boot sector to
  a file (under Linux, use "dd".)
* Fix the DOS installer to work for disks over 32 MB.
* SYSLINUX should now handle disks with more than 65536 tracks.

Changes in 1.37:
* Fix a bug that caused "label" statements in syslinux.cfg to
  not be handled properly.
* Updated the documentation.  Among other things, we now allow
  up to 128 "label" statements.

Changes in 1.36:
* Fix for booting old (pre-initrd) kernels.
* It seems at least some versions of OS/2 doesn't set up all
  the fields in the superblock correctly.  Account for that.
* Fix bug that caused boot failure when using the mem= option.

Changes in 1.35:
* Loading from partitions now should work properly.  (Actually
  tested, this time.  You should even be able to dd a floppy
  to a partition and boot from it.)
* Removed large workaround code for an alleged ancient BIOS
  bug I have never actually seen.  The -s option should work
  on those machines, anyway.
* Support for simple keyboard remappings, same as used by
  LILO (once again to support localization.)  The program
  keytab-lilo.pl from the LILO distribution included to
  generate such maps.
* Added a "safe, slow and stupid" (-s) option to the
  installers.  This option will lobotomize the boot sector to
  hopefully work on even very buggy BIOSes.

Changes in 1.34:
* Ability to load a VGA font on bootup (for localized Linux
  distributions.) 

Changes in 1.33:
* Bug fix in the Linux installer.
* Added a workaround for a bug in certain AMI/Intel BIOSes
  when booting from CD-ROM.
* Documentation changes.

Changes in 1.32:
* FAT16 filesystems are now supported.

Changes in 1.31:
* Now compiles under Linux, using NASM, rather than using
  Turbo Assembler under DOS.  See http://www.cryogen.com/Nasm
  for information about NASM.
* Linux-hosted SYSLINUX installer, as well as a
  rewritten DOS installer (now is written in assembler, so we
  don't need Turbo C.)

Changes in 1.30:
* Added support for loading bzImage and initrd loading, and made
  SYSLINUX new-setup-code aware (SYSLINUX 1.30 id=0x31).
* Added LILO-style kernel labels; see the LABEL and IMPLICIT
  keywords in README file.
* Added support for colorization of intro and help screens.
* The vga= option is now handled correctly.
* Massive rewrite of large chunks of the code in order to
  support the first two new features.

Changes in 1.20:
* Added simple online help at the "boot:" prompt.
* Removed 2880K image as I no longer have access to such a
  floppy drive. (Donations accepted!!)
* Decided to distribute the source in a subdirectory rather
  than in a nested zipfile.

Changes in 1.11:
* Removed a sanity check which would cause booting to fail on
  Phoenix BIOS version 4.03.  Apparently this BIOS is buggy.

Changes in 1.10:
* Added configuration file SYSLINUX.CFG.  This file contains all
  configurable options, and can be edited from any OS which can
  access an MS-DOS filesystem; there is no longer a need to run
  SYSLINUX.EXE except to write the boot sector.
* Default command line now given by "default" line in config
  file.
* LINUXMSG.TXT and BOOTMSG.TXT hard-coded file names replaced by
  "display" and "prompt" lines in config file.
* LILO-style option appending now supported ("append" line in
  config file).
* Prompt timeout is now supported ("timeout" line in config
  file).  The timeout is cancelled when anything is typed on the
  command line.
* Pressing <ESC> or <Ctrl-C> at the Loading... stage now aborts
  the kernel loading in progress and returns the user to the
  boot: prompt.
* The installer now automatically sets the READONLY flag on
  LDLINUX.SYS.
* Added 2880K disk image.

Changes in 1.03:
* Fixed bug that would prevent booting from double-density
  floppies and other DOS filesystems with multiple sectors per
  cluster.
* Added 720K disk image.
* Changed default kernel name on disk images to LINUX.

Changes in 1.02:
* Fixed bug that would garble the command line on recent kernels
  with more than 4 sectors of setup code (this wasn't really a
  *bug*; rather, a kernel change broke the code.  Unfortunately
  the Linux boot interface is still sorely undocumented).
* Added BOOTMSG.TXT file support (message file which does not
  force display of the boot prompt).

Changes in 1.01:
* Fixed bug on some (most?) 386 BIOSes would require two boot
  attempts.