The CD-ROM is recognized by the A-Series as a LIBRARY/MAINTENANCE format CD.

The names of the files on the CD are in the CD directory, which can be viewed using the SUPERVISOR PDT command or LFILES or COPYWRITE for NT.

The files can be copied from the CD using the LIBRARY/MAINTENANCE commands ADD and COPY. The unit is used exclusively by LIBRARY/MAINTENANCE.

SUPERVISOR, FLEX and COPYWRITE and COPYWRITE for NT, also provide these functions for CD Image Files.

This format is a modified ISO9660 format. The Volume Descriptor Type is 'FF' and the Standard Identifier is 'LMCD' or 'LMCDK' for a keyed CD. The directory file is called FILE000, and each subsequent file is called FILExxxxx, where the 1st file is FILE00001..

Each file has a Disk File Header(DFH) followed by blocks of data, like a LIBRARY/MAINTENANCE tape. On the CD the DFH and each block of data is preceded by a 2 byte field giving the data length in WORDS, followed by the data, and then a B6700 CheckSum word.

As each block is read from the CD, the MCP recalculates the CheckSum and compares it to the CheckSum in the record. If the CheckSums do not match, a Parity Error is reported.

A LIBRARY/MAINTENANCE CD may be verified using the COPYWRITE COPY to NULL feature, or by using the Verify Files feature of COPYWRITE for NT.

UNISYS release CDs to MCP 45 have blocks of up to 2700 words, and the files have Header Version 6.

COPYWRITE CDs have blocks of up to 900 words, and the files may have either Header Version 6 or 7, depending on the switches set on the COPY statement.

The CD-ROM is recognized by the MCP as an ISO9660 Data format CD.

The names of the files on the CD are in the ISO9660 directory, which can be viewed using the PD - on <family>(CD) command, or using FLEX, or on Windows.

FLEX on the A-Series and COPYWRITE for NT can be used to examine the files in a CD Image File.

The files can be copied from the CD, or CD Image File using the WFL statements COPY and ADD, and invoking COPYWRITE.

When a PD is done, or FLEX is used to process the files on the CD, the MCP File Attributes such as FILEKIND are visible.

When a file on a CD-ROM which has the extended attributes is opened, the MCP applies the attributes to the logical file. The attributes FILEKIND, MAXRECSIZE and MINRECSIZE, SECURITYTYPE, EXTMODE, CREATIONTIMESTAMP and ALTERTIMESTAMP are set.

A CD-ROM file with the extended MAXRECSIZE and MINRECSIZE attribute is changed to BLOCKSTRUCTURE = FIXED and may be handled as a fixed length record file.

It may for example be Label Equated to be a Compiler input file.

The MCP finds a valid LIBRARY/MAINTENANCE Primary Volume Descriptor, and therefore mounts it as a LIBRARY/MAINTENANCE CD volume. The MCP ignores any Supplementary Volume Descriptors.

Windows finds a valid ISO9660 Primary Volume Descriptor and a Supplementary Volume Descriptor with Escape Sequences identifying it as a JOLIET format, and so mounts the JOLIET partition. It ignores the LIBRARY/MAINTENANCE invalid ISO9660 Primary Volume Descriptor.

(Note: The Hybrid volumes created by CopyWrite prior to MCP 4.5 can only be mounted on Windows 95/98 and the A-Series, not Windows NT. For more information, please contact Metalogic).

Such a CD appears as a Data CD to the A-Series, which only recognizes the ISO9660 file system.

On Windows 95/98 or NT, the JOLIET file system is recognized in preference to the ISO9660 file system.

COPYWRITE for NT, and COPYWRITE on the A-Series can access any file system, independently of either Windows or the MCP.