HP 3000 Manuals HP 3000 Manuals
IntroducingCD Extensions for MPE/iX
by Merijane Lee
Software Technology Division
The HP CD extensions for MPE/iX are a client/server software utility that
allows PC applications, such as HP LaserROM, to access a shared CD-ROM
drive that is mounted on an HP 3000 system. This means you can now use
one CD-ROM drive for both LaserROM's electronic documentation as well as
for MPE/iX software updates (see articles on HPINSTAL/iX). (Note that
only one CD can be in the drive at any one time.)
Benefits
The HP CD extensions for MPE/iX (Part Number B3683AA) will provide you
the following benefits and new capabilities:
* Reduce your cost for support materials when specifying the
documentation on CD and Software-on-CD options
* Make LaserROM's complete set of MPE/iX documentation available on
the network to your PC users running MS-Windows
* Use the same CD-ROM drive on the HP 3000 for both LaserROM
documentation and CD-ROM software updates
* Share the CD-ROM drive among multiple, simultaneous users
* Operate MS-DOS and MS-Windows CD-ROM applications from the HP 3000
system, provided that the applications are compatible with the
Microsoft CD-ROM Extensions and do not use CD-Audio recording
Features
The HP CD extensions have been designed with the following features:
* Easy to administer via a CD-ROM Media Manager
* To the PC user, the networked CD drive appears as a normal drive
letter on the PC
* Utility is transparent to the PC user and requires no additional
user interaction after installation
* Supports multiple CD-ROM drives on an HP 3000
* Supports multiple simultaneous PC users
* Configurable cache sizes for data buffers on the HP 3000
* Configurable number of allowed connections
Technical Overview
Because the extensions are a client/server application, users must have a
network in place before they can use the product. The product is
designed for the TCP/IP network protocol and the use of the Microsoft
CD-ROM Extensions (MSCDEX). Following is a list of the hardware and
software prerequisites and a discussion of the product architecture.
Minimal Hardware and Software Prerequisites.
* An HP 3000 with 32MB RAM using MPE/iX 5.0 or greater and running
Network Services (NS). A 9x7LX is recommended.
* A 386 or 486 PC with 4MB memory, running MS-DOS 5.0 or 6.0, and
MS-Windows 3.1
* 52KB of available conventional memory on the PC
* Toshiba XM-3401TX CD-ROM drive or equivalent, such as:
* HP C3560U CD-ROM SCSI expansion upgrade kit
* HP A3086A CD-ROM for integrated 9x7 SPU's
* HP A1999A external SCSI CD-ROM drive (supported but no
longer purchasable)
* Local Area Network consisting of either
* Microsoft LanManager 2.1 or 2.2, or
* Novell NetWare 3.11 or 4.0 in conjunction with
* WRQ 3000 Connection 2.1, or
* HP J2246A PC Arpa Network Services
Product Architecture.
Following is a schematic of the architecture for the CD extensions.
Boxes outlined in ***** represent components provided as part of the
product.
HP3000 System
|-------------| |------------------------------------|
| ISO 9660 |----| I/O Subsystem |
| CD-ROM Disk | | Volume Management |
|-------------| | MPE/iX 5.0 |
**************************************
* Server * Media *
* (CDSERVER) * Manager *
* * (CDMGR) *
**************************************
| Network Services |
| BSD Sockets API |
| TCP/IP |
|------------------------------------|
|
|
PC Client |
|------------------------------------|
| TCP/IP |
| BSD Sockets API |
|------------------------------------|
| HP PC Arpa | WRQ 3000 | |
| Network | Connection | |
| Services | | Microsoft|
|-------------------------| LANMgr |
| | LAN |
| Novell NetWare LAN | |
| | |
**************************************
* Pseudo CD-ROM Device Driver *
* *
**************************************
* Microsoft CD-ROM Extensions *
* (MSCDEX) *
**************************************
| DOS/WINDOWS |
|------------------------------------|
| HP LaserROM | PC App |
| | |
|------------------------------------|
The Client Side: Microsoft CD-ROM Extensions.
The Microsoft CD-ROM Extensions (MSCDEX) are an extension to the MS-DOS
operating system which permits the reading of CD-ROM disks that have been
formatted under specifications for either the ISO-9660 or the High Sierra
Group Standards. MSCDEX is a Terminate-and-Stay-Resident (TSR) program
that works in conjunction with a device dependent driver provided by the
hardware vendor of the CD-ROM drive. The driver accepts data requests
from MSCDEX and allows a CD-ROM disk to appear as just another drive
letter to the user and to applications. Under MS-Windows, you will
notice that a CD-ROM drive letter is symbolized with a slightly different
icon from a hard disk or floppy disk drive.
With the HP CD extensions, the driver that responds to MSCDEX is actually
a pseudo device driver (the Client) that transmits the commands, via a
TCP/IP network protocol, to the Server software (CDSERVER) running on the
HP 3000. On the MPE/iX side, the CD-ROM drive is mounted on the file
system as an unknown volume and accessed by CDSERVER as a read-only
device. The CD-ROM drive exhibits the characteristics of a disk class
device, e.g., if you disconnect it from the system, I/O requests to it
will queue up until satisfied.
The Server Side: Cache and Media Management.
Using HP Berkeley Sockets for MPE/iX , CDSERVER translates network
requests, accesses the CD-ROM drive, packetizes the data that is read,
and sends it across the network to the Client. CDSERVER contains a
dispatcher and a cache manager to accommodate multiple concurrent users;
there is a cache for each CD-ROM drive on the HP 3000. The size of the
cache is configured by the system administrator.
Note that the HP 3000 server software for the extensions is bundled in
the FOS for MPE/iX 5.0. The client software and the Administration and
Installation guide come with the B3683AA product.
The Media Manager.
To administer the CD-ROM drive, a Media Manager program (CDMGR) is
provided. CDMGR allows you to mount or dismount a drive, manage PC
connections, turn off CDSERVER, and list CD-ROM devices. To ensure that
CD's are not arbitrarily switched out from under users, the drive door is
locked and the CD cannot be ejected until the administrator dismounts the
drive.
NOTE The extensions do not allow you to read a CD-ROM file system
directly from the MPE command line or the Media Manager. You must
use the DOS or MS-Windows interface in order to type, print, or
copy a file on the CD.
Configuration and Performance
Performance of the networked CD-ROM drive will vary, depending on your HP
3000 model, PC processor, LAN card, the available capacity on your
network and 3000 host, and the number of users concurrently accessing the
CD.
You will also need to consider memory management on the PC. MSCDEX
requires 32KB of conventional memory, and the HP CD extensions pseudo
device driver requires an additional 16KB.