JDS5.TYM%OFFICE-2@sri-unix.UUCP (11/04/83)
in PC/XT mode, the XT/370 is compatible with current
PC/XT capabilities including use of "foreign" expansion boards.
The Hardware
The XT/370 consists of a standard PC/XT chassis with eight expansion
slots. Three of these slots are populated with special S/370
emulation cards.
PC/370-P card The P card implements an emulation of the 370
instruction set. The card contains three
microprocessors.
1. One of the processors is a heavily modified
Motorola 68000 produced by Motorola under
license to IBM. This chip implements the
general purpose registers, the PSW,
instruction fetch and decode logic, and 72
commonly used S/370 instructions. Since the
chip is manufactured under license to IBM, it
is doubtful that it will appear as a Motorola
product.
2. A second processor is a slightly modified
Motorola 68000 which will be listed in
Motorola's catalog. This chip emulates the
remaining non-floating point instructions,
manipulates the page table, handles exception
conditions, and performs hardware
housekeeping.
3. The third microprocessor is a modified Intel
8087 which executes S/370 floating point
instructions. This chip is interfaced as a
peripheral rather than via the normal 8087
co-processor linkage.
PC370-M card The M card contains 512KB of parity checked RAM.
This memory may be accessed from the P card or from
the XT's native 8088 processor. Concurrent requests
are arbitrated in favor of the 8088. While the M
card does live in an XT expansion slot, it is also
connected to the P card via a special edge
connector. 16-bit wide transfers between M card
memory and the P card are effected through this
connector (normal XT memory transfers operate in
8-bit wide chunks).
When operating in native PC mode, the M card's
memory is addressed as contiguous memory beginning
at the end of the 256KB memory of the system's
motherboard. In native PC mode, the XT/370 has
640KB of usable RAM - some of the M card's memory is
not used.
When operating in 370 mode, only the 512KB RAM of
the M card is usable (i.e., the 256KB on the
system's motherboard is not available for the VM/CMS
system). The first 480KB of this memory implements
480KB of real S/370 space. The remaining 32KB on
the M card functions as a microcode control storage
area for the second P card microprocessor.
Of the 480KB of S/370 memory, the first 64KB are
consumed by VM/PC leaving 416KB of real memory for
user programs. User programs larger than this are
handled via paging.
PC/3277-EM card This card attaches the XT/370 to a S/370 mainframe
via a local or remote 3274 control unit (connection
via coaxial cable). When VM/PC is running, the EM
card enables the XT/370 to emulate a 3277 model 2
using the IBM monochrome or color display (since the
3277 does not support color, if a color display is
used, then default colors are utilized). Under
VM/PC, the EM card is also used in uploading and
downloading of data between a host VM system and the
XT/370. A 3274 coaxial connection can transfer data
about as fast as today's small winchester disks
(over 600,000 bytes/second).
Software
The XT/370 can run in native PC/XT mode or in S/370 mode under VM/PC.
Under VM/PC, the user can alternate via a "hot key" between a local
CMS session and a remote 3277 session (or optionally, a 3101
emulation session). VM/PC on the XT/370 will support all VM/CMS
software conforming to the following requirements.
- Uses no more than one virtual address space.
- Runs in a virtual machine of up to 4 MB.
- Supports 3277 model 2.
- Does not rely on protection exceptions.
- Does not depend on S/370 DOS emulation.
- Does not exceed fixed disk capacity.
- Does not require more than 416KB of real memory.
- Does not rely on internal VM/SP and/or HPQ structure and
formats.
- Does not rely on time dependent operations.
In effect, this means that most S/370 CMS software will run on the
XT/370. Some notable exceptions:
- PROFS does not run because it utilizes multiple virtual
machines,
- ISPF does not run because it depends on CP internals,
- any program using VSAM will not operate properly because VSAM
uses non-standard disk formats (S/370 DOS emulation); this means
that PL/I software using indexed files will not run on the
XT/370.
VM/PC does not offer a true VM-like environment. Rather, it provides
an environment in which CMS applications can run. Non-CMS VM
applications will not run on the XT/370.
Within the supported CMS environment, each CMS minidisk (simulated
disk-pack on which a CMS user stores many files) is implemented as a
PC-DOS file. This is very nice since it enables the use of PC-DOS
commands to backup CMS data and to move this data between XT/370
workstations.
IBM will license IBM S/370 software for use on the XT/370. Licensing
agreements are made in conjunction with the original mainframe S/370
license (i.e., for now, you must be a S/370 licensee to license IBM
S/370 software for the XT/370) and the corresponding software must be
downloaded from a S/370. License fees run a few dollars per month per
XT/370 workstation for each licensed software unit. IBM has announced
the following software to be available for licensing.
Product Monthly Charge
---------------------- ----------------
OS/VS COBOL Compiler and Library $19
OS/VS COBOL Library 6
COBOL Interactive Debug 21
VS FORTRAN Compiler and Library 17
VS FORTRAN Library 4
IBM BASIC Processor and Library 21
PL/I Optimizing Compiler and Library 21
PL/I Transient Library 4
PL/I Resident Library 4
Pascal/VS 11
Assembler H 9
Document Composition Facility (SCRIPT/VS) 18
License fees for IBM CMS software are charged to the mainframe
licensee rather than to the XT/370 proprietor. But how can IBM
enforce these fees? When this question was posed at a recent
professional meeting, IBM representatives responded that IBM would
continue to trust its customers. In corporate environments, where the
XT/370 will be sold, this is probably quite reasonable.
The VM/PC system must also be licensed. It is provided on six floppy
diskettes and includes the VM/PC Control Program, CMS, XEDIT, EXEC2,
local and remote file transfer utilities, and the 370 Processor
Control package.
370 Processor Control is a general purpose debug facility similar to
the debug facilities found on the operator consoles of S/370
processors. It runs on the XT/370 under VM/PC as one of several
concurrent sessions (including a local and a remote CMS session). It
can be entered from any other session and can exit to any session.
370 Processor Control enables the user to:
- stop and start the processor,
- stop the processor by real instruction compare,
- generate an external interrupt to the processor,
- edit (full screen mode) the following:
* 370 general purpose registers,
* 370 floating point registers,
* 370 control registers,
* 370 PSW,
* 370 storage, both real and virtual,
* 370 page address table.
The user interface to the 370 Processor Control session relies heavily
on function keys whose usage is displayed on the screen.
XT/370 VM/PC CMS and CP commands are similar to S/370 VM/SP release 2
commands. From the looks of the list given in the VM/PC announcement
notice, most CMS and CP commands are supported. VM/PC XEDIT and EXEC2
are compatible with the corresponding software of VM/SP release 2.
Included on the distribution diskettes with VM/PC is a remote server
program which may be used on a S/370 host to support communications
between the host and the XT/370. This program affords the following
functions:
- Spool, disk, and file services,
- VM/PC service request processing,
- Logical and physical communications management.
We aren't quite sure how you would upload this program to a host
without the services of the program itself.
Performance
The XT/370 has been in the field at a number of locations for several
months. First rumors on performance of the XT/370 CPU indicate that
it is approximately half of a 4331 when running a commercial
instruction mix. When running scientific codes, twice the performance
of the 4331 is expected. In general, the CPU is categorized as a .1
MIP processor. This may not sound terribly impressive in times when
we are used to multi-MIP single chip micros. Remember however, that
.1 million S/370 instructions are likely to produce substantially more
computing than .1 million instructions of your standard micro chip.
The XT/370 running in S/370 mode can access the 512KB on the M-card.
Of this 512KB, 32KB are reserved for microcode control storage; 64KB
is used up by the VM/PC Control Program. This leaves 416KB for user
programs. Should a user program require more memory than this, then
VM/PC will use a paging area on the XT/370's hard disk swap pieces of
the program in and out of memory according to usage.
Swapping on the little 10MB hard disks is going to be considerably
slower than on the large disks used with mainframes. Thus, programs
larger than 416KB will probably run very slowly. Field test users
report long delays in loading large programs into memory even when
these programs are well under the maximum for non-paged operation
(e.g. XEDIT). Again, this is directly attributable to the relatively
slow operation of the XT/370 hard disks.
While 10MB sounds like a great deal of disk space to those of us who
have been using floppies, in the mainframe world 10MB is just a drop
in the bucket. In its XT/370 product announcement, IBM cites the
following example of disk utilization.
bytes(MB)
System storage (VM/PC, DOS) 1.6
OS/VS COBOL Compiler and Libraries 1.0
Document Composition Facility 0.6
Page file (1 MB virtual) 1.0
User A disk for CMS data/programs 3.0
Spooling for printing 0.5
User area for PC data/programs 2.3
-------
total 10.0
Here we have but 1MB as a paging area (reduces the maximum VM/CP
virtual job size from 4MB to 1MB) and .5MB for spooling. The 20MB
XT/370 option (see below) will undoubtedly be quite popular.
Configurations and Prices
XT/370 (IBM machine number 5160) is announced in two configurations:
model 588 and model 568.
[5160 is also the model number of regular XTs. -Ed.]
The 5160 Model 588 is the XT-like system we have been describing. It
includes one floppy and one 10MB hard disk drive (or as IBM calls it,
a "fixed" disk drive). The price for this configuration is $8995.
VM/PC is available for an additional one time license fee of $1000.
Model 568 is the same as the 588 but without the hard disk and the
hard disk controller board. To augment this configuration, you may
purchase a new IBM PC option, the 5161 expansion unit model 3. This
unit comes with two 10MB hard disk units, a hard disk controller, and
eight system expansion slots (six full-feature and two short slots).
The XT/370 model 568 is priced at $6720 and the expansion unit price
is $4970. Thus a 20MB XT/370 costs $11690. Add $1000 for VM/PC and
you're all set to go for about $13K (tax included).
The three XT/370 boards are available as an upgrade for the IBM PC/XT.
The upgrade kit contains the boards, installation instructions, and a
logo kit to change the name plate to read "IBM XT/370". Thank heaven
for IBM! The price of the XT upgrade is $3790.
The 3270-PC
The 3270-PC combines the functions of IBM's 3270 display system with
those of the IBM PC and can support up to seven concurrent activities:
one local PC-DOS 2.0 session, four remote mainframe sessions, and two
local electronic notepads. Users can associate activities with
windows and can designate which windows appear on the system's
display, the size of those windows, and their positions. With the
assistance of the 3270-PC Control Program, information can be copied
between windows with the exception that a PC-DOS window may not
receive information.
An important limitation of the 3270-PC is that it does not support
PC-DOS applications which make use of "APA" graphics (APA stands for
"all points addressable", IBM's jargon for bit-mapped). This
eliminates all PC software which operates in non-text mode. Only
programs which can run on a PC equipped with IBM's monochrome display
adaptor (non-APA display) will be able to run on the 3270-PC.
The Hardware
In appearance, the 3270-PC closely resembles the original PC. Unlike
the XT/370, however, the 3270-PC is not essentially an upgrade of the
the PC - nor is an upgrade kit for the PC available.
The differences stem largely from the display section of the hardware
which has been substantially altered. Hardware window management
functions have been added and are implemented on a new board, the
5151/5272 display adapter. This adapter is used in place of the PC's
monochrome or color/graphics display adapter and provides text-only
displays in eight colors. While the extended character graphics of
the PC are available, no bit-mapped graphic capabilities are
supported.
The 3270-PC can be configured with the PC's monochrome display for
black and green text-only operation or can be fitted with a new
product, the 5272 color display. The new display is a 14-inch color
monitor from Matsushita. Initial reports indicate that the display
produces superb text images. Color text images displayed by the 5272
are said to be of the same general quality as those displayed by the
PC's monochrome display.
The 3270-PC includes a new keyboard which addresses some of the
complaints about the PC's keyboard. Even though the keyboard contains
more keys, the layout is apparently improved. The return and shift
keys have been enlarged. The cursor keys have been pulled out of the
numeric keypad to form their own little group between the main set of
alphanumeric keys and the numeric keypad. Twenty function keys
arranged in two rows of ten have been added at the top of the
keyboard. To help clarify keystroke operations, the new keyboard is
annotated. Blue legends are used to designate PC specific functions;
black legends indicate 3270 functions.
The 3270-PC includes two expansion boards not found in the PC.
3270 System adapter
Supports communication between the 3270-PC and the
remote 3274 controller through which mainframe hosts
are accessed; connects to a 3274 via coaxial cable;
one physical 3274 connection can support four
logical connections; can optionally be attached to
43xx display/printer adapter.
Keyboard adapter
Interfaces the new keyboard to the system unit; the
key keyboard connects directly to this board rather
than to the mother board as it does for the PC.
The system unit provides eight "expansion" slots of which six will
normally be filled upon delivery with the 3270 system adapter, a
memory expansion board, the display adapter, the diskette drive
adapter, the printer adapter, and the keyboard adapter. If a hard
disk is added, then the seventh slot will be used for the hard disk
adapter. Certainly, the memory expansion and printer adapter
functions could be coalesced onto a single foreign board, but this
would only slightly relieve slot paucity.
Software
The 3270-PC runs under control of the 3270-PC Control Program in
conjunction with PC-DOS 2.0 and supports concurrent operation of up to
four remote host interactive sessions, up to two local notepad
sessions, and one PC-DOS session.
The Control Program enables users to associate sessions with display
screen windows and to manage those windows via a set of functions that
IBM calls advanced screen management.
Window Definition
Users can define windows that permit viewing of all
(up to 2,000 characters) or part of a presentation
space. In IBM's parlance, a presentation space is a
logical display area presented by a single host.
PC-DOS presentation spaces are 2,000 characters
(i.e., 25 lines by 80 characters), remote host
spaces are up to 3,440 characters, and notepad
presentation spaces are 1,920 characters.
Window View within a Presentation Space
Up to seven windows may appear on the screen at
once. Each window is associated with a distinct
presentation space. Windows may be as large as the
screen or as small as one character and may be
positioned at any point within their presentation
space. Thus, a window which is 20 characters wide
by 4 lines long might show the first 20 characters
of the last 4 lines of an emulated 3270 remote host
session display. Window size and position within
the presentation space may be changed at any time
without effecting the content of the presentation
space.
Window Positioning on the Screen
Each window may be positioned to appear at any
position on the 3270-PC's physical display screen.
A window may partially or completely cover one or
more other windows. Windows may be repositioned at
any time without effecting the content of the
associated presentation spaces.
The Active Window
At any given moment, one window on the 3270-PC
screen is the active window. When users enter
information from the keyboard, it is directed to the
session associated with the currently active
window. Users can switch between active windows
through keystroke commands.
Background/Foreground Color
Users may define the foreground and background
colors of host session windows not using extended
data stream attributes. Users may also define the
background color for the 5272 screen (i.e., the
color to be displayed in areas not occupied by
windows).
In addition to the advanced screen management functions, the control
program offers a number of related facilities which help users to
further manipulate and utilize the 3270-PC environment.
Copy Data Between Windows
Data may be copied within or between any
presentation space except into the PC-DOS space.
MS-DOS screen management is simply not prepared to
handle block data inserts as is the 3270 world.
Notepads
The notepad activities may be thought of as local
electronic scratch pads which users may use at their
convenience. The contents of a notepad may be saved
and restored at any time using PC-DOS files as the
storage medium.
User Defined Keystroke Sequences
Keystroke sequences may be captured and recorded (in
PC-DOS files) for future playback.
Screen Configuration Memory/Recall
Users can define up to ten screen configurations
each of which describes a set of windows configured
in any way, and can cause any one configuration to
be displayed upon command. PC-DOS files are used to
store the configuration information.
Screen/PC-DOS Session Window Print
A full copy of the display screen may be printed on
a local printer. Similarly, a full copy of a PC-DOS
presentation space may be printed on a local
printer.
Host Session Window Print
A full copy of any host presentation space may be
printed on a local printer or on a 3274 attached
printer (or a 43xx display/printer attached terminal
printer).
System Status Line
The Control Program maintains a status line at the
bottom of the screen which displays current
configuration information including the name of the
active window.
Help + Tutorial
The Control Program includes a Help function which
displays active workstation functions and sessions
and an online tutorial that explains and simulates
system functions. The tutorial is a standard PC-DOS
program which can be run on any IBM PC.
Host File Transfers
The Control Program with the assistance of a
host-based IBM 3270-PC File Transfer Program can
initiate transfers of ASCII, binary, and EBCDIC
files to and from remote hosts. The host-based file
transfer program is host licensed and is available
for VM/SP 2.1 and MVS/TSO.
Configurations and Prices
The 3270-PC (IBM machine number 5271) is announced in three
configurations.
The 5271 model 2 is a single dual-sided floppy system which includes a
system unit with 256KB RAM (expandable to 640KB) and keyboard. The
price for this configuration is $4,290. To this will normally be added
a PC monochrome display at $345 or more likely, the new 5272 color
display at $995. The 3270-PC Control Program will be available for a
one time license fee of $300. All told, getting into a 3270-PC, even
one with only a single floppy, will cost at least $4935. If you want
the nice color display the price is $5585. This model does not
include a printer adapter as standard equipment.
The 5271 model 4 adds a 64/256KB memory expansion board with 64KB RAM
installed, a printer adapter and printer cable, and a second
dual-sided floppy disk drive to the features of the model 2. The base
price for the model 4 hardware is $5319. Adding the Control Program
and a monitor, the dual diskette system is priced at $5964 for a
monochrome version and $6614 for the color version.
The 5171 model 6 is like the model 4 except that a 10MB hard disk is
added instead of the second floppy. The base price of the model 6 is
$7180. Adding a monitor and the Control Program brings the total to
$7825 for a monochrome system and $8475 for the color version.
The following table summarizes 3270-PC pricing information.
single dual diskette +
diskette diskettes hard disk
(model 2) (model 4) (model 6)
------------------------------------
| |
monochrome | $4935 $5964 $7825 |
display | |
| |
color | $5585 $6614 $8475 |
display | |
------------------------------------
3270-PC PRICES INCLUDING DISPLAY AND VM/CP
S/370 installations supporting attachment of 3270-PC systems will want
to license IBM's host-based 3270-PC File Transfer Program. The charge
is a one time license fee of $600 for each VM/SP or MVS/TSO operating
system environment within which the file transfer functions will be
used.
Jeffrey Stone
Menlo Park, CA
October 21, 1983