@comment -*- Mode:Text; Package:USER; Readtable:CL -*-

@subsection Region Table Expanded

The region table has been expanded.
While it was possible to run out of memory in Release 3
due to a limitation on region pointer entries,
this is far less likely to occur in Release 4.
In Release 3, the region table was limited to 256 entries; the limit has been expanded to 1536.

@subsection Garbage Collector

The function @l[gc:gc-off] now waits for ongoing garbage collection to
finish before turning off the garbage collector.

@subsection Disk Partition Functions

@l[si:service-disk-partition] has two new keyword arguments, :subset-start and
:subset-n-blocks.  @l[si:copy-disk-partition], @l[si:compare-disk-partition],
and @l[si:copy-disk-partition-background] make use of these keywords.  As a
result, parts of disk partitions may be compared and transmitted
between machines in a protocol-independent fashion.

@subsection Synonym Streams

The new function @l[si:follow-all-syn-streams] extends the functionality of
@l[si:follow-syn-stream], following the synonym stream or streams of the
argument stream to the end of all indirection.  @l[FORMAT] now uses this new
functionality to avoid cases in which microcode loops could occur.

@subsection Special Forms

The following special forms now have the :source-file-name property
(and therefore, they can be edited with @meta[.]):
@itemize @bullet
@item
DEF
@item
DEFF
@item
DEFUN
@item
DEFSUBST
@item
MACRO
@item
SIGNP
@end(itemize)

@subsection Calling LOAD Within a Patch File

Attempting to call LOAD from within a patch file no longer
causes a fatal error.
Instead, a continuable error is generated, from which
the user may proceed.

@subsection Disk Save

The function @l(DISK-SAVE) now makes additional preparations for preserving
the current Lambda state onto the disk:

@itemize @bullet
@item
The Zwei histories *KILL-HISTORY*, *DEFINITION-NAME-HISTORY*, and
*PATHNAME-ARGUMENT-HISTORY* are erased;
@item
The Chaosnet software is reset;
@item
Garbage collection is re-enabled (but only if it was enabled at the time of the
call to @l[disk-save] -- @l[disk-save] must turn off the garbage collector
to perform certain parts of its duties).
@end(itemize)

@subsection Serial Ports

The @l(:FLAVOR-AND-INIT-OPTIONS) keyword argument to @l(OPEN)
was not being handled correctly when opening a stream to a serial port.
Using this keyword is the correct way to open a serial port stream
of the desired flavor.

The serial port stream flavors are:

@table 3

@item si:sdu-serial-stream @findex[si:sdu-serial-stream]

@item si:sdu-serial-ascii-stream -

Converts LISP machine characters to ASCII characters (on output),
and ASCII characters to LISP machine characters (on input).

@item sdu-serial-xon-xoff-stream -

Provides software (Xon/Xoff) flow control on the serial port.

@item si:sdu-serial-ascii-xon-xoff-stream -

Combines ASCII translation and software flow control.
@end(table)

@group
For example, the following example opens a stream on serial port B
at 9600 baud with ASCII character translation and software flow control:

@lisp
(open "SDU-SERIAL-B:"
      :flavor-and-init-options
      `(si:sdu-serial-ascii-xon-xoff-stream
	:baud-rate 9600.))
@end(lisp)
@end(group)