Viatcheslav,
Alan has given you some good links below.
At risk of possibly going slightly off topic for your test questions, I
shall explain a little further what Alan already mentioned, that the
machines that used to be called A Series are only one of the two mainframe
architectures that Unisys make under the ClearPath label. The other type is
the 2200 series, as Alan said. Both of these mainframe systems are now
designated as "ClearPath" servers, although their architectures and
operating systems are in fact totally different from each other. Nowadays,
the two series of machines are normally differentiated within the Unisys
community by their operating system names - the A Series systems run under
MCP (Master Control Program, I think), while the 2200 systems run under the
eponymous OS2200, previously known as Exec 8.
The MCP machines (also still known informally as A Series) use the
EBCDIC code set, like IBM mainframes, and a 48-bit word made up of 6 x 8-bit
bytes. They are a true stack architecture (implementing stack control as
required in ALGOL and the c-based languages inherently at the hardware
level); even the operating system is written in a dialect of Algol, so that
in effect there is no "machine code" per se.
The OS2200 systems, on the other hand, have a 36-bit word that can be
handled as either 4 x 9-bit ASCII bytes (normally) or 6 x 6-bit FIELDATA
bytes (for old applications). OS2200 systems were originally designed as a
classic "flat" architecture, but the modern systems can run either flat or
stack depending on processor settings. Most of OS2200 is written in 2200
Assembler, but some parts were subsequently developed a proprietary language
called PLUS, and some more recent bits are coded in c.
Both ClearPath architectures also run Java, and both have hardware
memory protection features that effectively render it impossible to create
buffer overrun exploits of the type which form the basis of 90% or so of
Internet hacking attacks. This is why the company currently promotes them as
"Secure Java" platforms.
I hope this helps you with your test - good luck with it.
Regards
Colin
Post by Alan PontingPost by v***@lycos.comI am going to write a technical test on modern technologies in about 10
days, which will
include several questions on UNISYS A Series. I am not even sure, what
is UNISYS, what is
ClearPath, what is the relationship between the two. Most likely I will
have to answer simple basic
questions. Could anybody provide me with some links, where I can
quickly upgrade myself on the
topic? Currently I am trying to read CANDE operations manual and UNISYS
system operation
guide, but both seem to be compiled for an advanced user.
Thank you.
Viatcheslav
Take a look at wikipedia for some history of Unisys. It touches on the
Burroughs ( B-series, A-Series ) side and the Sperry (OS1100/2200) side -
which remain to this day - despite the merger of Burroughs and Sperry to
make Unisys..
http://en.wikipedia.org/wiki/Unisys
If I read your question correctly, you are interested in the old Burroughs
side. Hardware started (using term loosely) with B-series machines
(B6700, B7700, etc) machines which evolved into A-series machines (A9,
A11, A16, A19, etc) which evolved into ClearPath machines (NX5600, NX6800
etc) which evolved into ES7000 based machines (Libra 580/590, 680/690 etc)
machines.
All Unisys manuals are available for free at http://support.unisys.com
(click the documentation link at the bottom).
Alan Ponting