DUCM/DYC Release 4 2nd January 1989 This is a distribution of large disk handlers for DU (MSCP) disks. Full source and documentation is included. These have been tested and work fine on Fujitsu Eagles running TSX-Plus Version 6.2. A mapped RX03 floppy disk handler is included as well, if you want it. It requires a SIGMA or DILOG RX03 controller. If run as a programme it allows you to format discs, requiring no privileges under TSX-plus. Concerning the files on this disc: the abstract is ABSTRA.CT, and this file is READ.ME. There are three sections to this distribution: (1) the DUCM section, which is the handler for DU (MSCP) discs; (2) the WA section, which is the special handler for using large discs under TSX-plus; and (3) the DYC handler, which is an RX03 handler for Sigma/Dilog controllers, and which may be mapped under TSX-plus. Please read DUCM.DOC to find out what to do. [It consists of three manuals, a basic one, and the full ones for DUCM and WA. You do not have to read the full ones to be able to use these handlers.] DUCM.DIS and DYC.DIS give a sort of overview of the contents of each of the logical discs (on DUCM.DSK and DYC.DSK respectively). They are the command files used to create this distribution. Version 2b fixed an occasional data corruption problem which occurred rarely on heavily loaded and heavily swapping systems. Version 2c included fixes to the serious error code, and has had time-out support added. Version 2d tidies yet another bug, and places a safety restricion on the timeout code under TSX-plus. Version 3 added the MSCP BYPASS facility (use with care!). This facility requires that the user MSCP buffer size be 60 (octal) - the same as in the handler. As the DEC subroutines JREAD/JWRITE and IGTDUS use this size, it should not be a significant problem. [Despite having used the buffer address code from DEC's DU handler for the XM monitor version of this handler, I am very suspicious that an XM system running multiple jobs all of which are rapidly accessing the disc, could be crashed by both this handler and DEC's. This is due to the primitive form of DEC's $RELOC.] Version 3a fixed a bug if there were a time-out error during initialization. Version 3b added an extra FORK level to timeout initialization, as TSX V6.31 fell over in funny ways if this were merely included in normal init code. Version 4 rewrote large chunks of the handler to get around a nasty bug in TSX V6.31 (NOT gotten around in V3b of DUCM). Chester Wilson Charleville 4470 Australia.