To:	Users
From:	Bob Supnik
Subj:	Simulator V2.3, V2.3a, V2.3b Release Notes
Date:	1-May-98

This memorandum documents some of the key changes between V2.3 of the
simulators and prior versions.

I. V2.3

1. Revised magnetic tape format

In prior versions, simulated magnetic tape records were stored as a
16b byte count followed by the bytes of the record (with a pad byte
if the record count was odd).  In V2.3, records are stored as a 32b
byte count, followed by the bytes of the record (again padded if
necessary), followed by a copy of the 32b byte count.  This allows
much more efficient handling of tape backspace commands.

To help with data conversion, the sources now include a small utility
program, mtcvtv23.c.  This program converts a pre-V2.3 simulated
magnetic tape data file to V2.3 format.

2. Automatic big endian support

In prior versions, data files were assumed to be in little endian
format.  Execution on big endian systems required insertion of endian
conversion code in the sources.  In V2.3, all endian conversions are
performed automatically.  Data files are still stored in little endian
format by default.

3. TERMIOS UNIX terminal support

In prior versions, UNIX terminal I/O was done using the BSD terminal
primitives.  In this version, terminal I/O is done with the POSIX
compliant TERMIOS primitives.  If your UNIX does not support TERMIOS,
use flag -DBSDTTY in your compilation commands.

II. V2.3a

V2.3a contains bug fixes and a few functionality enhancements:

- Added search capability
- Added bad block table command to PDP-11 disks
- Added bootstrap to PDP-11 magtape
- Added additional Nova moving head disks
- Added RT-11 sample software
- Fixed bugs in PDP-11 RM/RP disks
- Fixed bugs in Nova moving head disks
- Fixed endian dependence in 18b PDP RIM loader

III. V2.3b

V2.3b contains bug fixes and a few functionality enhancements:

- Added RIM loader as PDP-8 paper tape bootstrap
- Fixed bug in PDP-8 RF bootstrap
- Fixed bug in PDP-11 symbolic display
- Fixed bugs in PDP-11 floating point
- Added alternate bootstrap for PDP-11 magtape
