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cybertheque
Technical User
As part of my efforts to backup Merlin Mail R3 and Merlin Legend Mail systems (and to restore to replacement hardware) I have been experimenting with Concurrent DOS XM 5.2, hard disks and the application software, and am passing along some notes for future reference.
Merlin-Mail V3, running on the stock 286 hardware with Brooktrout ROM BIOS (serial console) uses a Maxtor 40 MB Hard Drive with geometry of 965 cyls X 5 hds X 17 spt and a single CP/M partition.
The drive when transferred to an NEC 386sx-40 PC (VGA video) will boot and run with console on COM1, permitting software maintenance on standard hardware, use of the floppy drive, etc. Attempts to run the mm application with voice cards installed however results in failures in viosreq (incompatible line card rom message).
Merlin Legend Mail V1.04 hard drive Toshiba HDD2714E (1443MB) contents were saved as an image file using 'dd' (on a unix system) and a large number of bad sectors past 50MB were present.
Analysis of the partition tables and directory structure show the geometry used by the 007MLM card as 912 cyl X 15 hds X 60 spt despite the drive's reported geometry of 2796 cyl X 16 hd X 63 spt; other people have reported that the MLM can be found with a variety of drive sizes, however only about 300MB is actually used and the geometry in the BIOS is always 912 X 15 X 60. The drive image was copied to a 540MB drive with a native geometry of 1050 X 16 X 63, and it was installed in the same 386sx machine described above with a custom BIOS drive type of 912 X 15 X 60. On boot, the system reports "Loading from DOS partition 2" on the vga screen but then does not provide the console on COM1 or on the KBD/VGA. If the machine is booted with DR-DOS 7.03, the DOS partition is available as drive C: and FDISK reports the proper MLM partition structure:
(note: monospace font needed to preserve formatting of table)
PART # START END MB STATUS TYPE
------ ----- ---- --- ------ ----
1 11 461 197.7 N Concurrent DOS
2 462 912 197.7 N Concurrent DOS
3 C: 1 10 4.3 A PRI DOS FAT12
- 11 911 395.5 free space
Thus, both the CP/M and FAT12 partitions are available for access and maintenance. This drive should then work in the 007MLM as a replacement for the failing drive. Note that other drives should work if they have at least 15 heads of native reporting geometry; areas of the surface referenced using heads above 15 will not be used (as is the case with the drive in this example and also with the drive being replaced -- there is no LBA/CHS translation since the BIOS dates of these systems are from 1992 and earlier).
Merlin-Mail V3, running on the stock 286 hardware with Brooktrout ROM BIOS (serial console) uses a Maxtor 40 MB Hard Drive with geometry of 965 cyls X 5 hds X 17 spt and a single CP/M partition.
The drive when transferred to an NEC 386sx-40 PC (VGA video) will boot and run with console on COM1, permitting software maintenance on standard hardware, use of the floppy drive, etc. Attempts to run the mm application with voice cards installed however results in failures in viosreq (incompatible line card rom message).
Merlin Legend Mail V1.04 hard drive Toshiba HDD2714E (1443MB) contents were saved as an image file using 'dd' (on a unix system) and a large number of bad sectors past 50MB were present.
Analysis of the partition tables and directory structure show the geometry used by the 007MLM card as 912 cyl X 15 hds X 60 spt despite the drive's reported geometry of 2796 cyl X 16 hd X 63 spt; other people have reported that the MLM can be found with a variety of drive sizes, however only about 300MB is actually used and the geometry in the BIOS is always 912 X 15 X 60. The drive image was copied to a 540MB drive with a native geometry of 1050 X 16 X 63, and it was installed in the same 386sx machine described above with a custom BIOS drive type of 912 X 15 X 60. On boot, the system reports "Loading from DOS partition 2" on the vga screen but then does not provide the console on COM1 or on the KBD/VGA. If the machine is booted with DR-DOS 7.03, the DOS partition is available as drive C: and FDISK reports the proper MLM partition structure:
(note: monospace font needed to preserve formatting of table)
PART # START END MB STATUS TYPE
------ ----- ---- --- ------ ----
1 11 461 197.7 N Concurrent DOS
2 462 912 197.7 N Concurrent DOS
3 C: 1 10 4.3 A PRI DOS FAT12
- 11 911 395.5 free space
Thus, both the CP/M and FAT12 partitions are available for access and maintenance. This drive should then work in the 007MLM as a replacement for the failing drive. Note that other drives should work if they have at least 15 heads of native reporting geometry; areas of the surface referenced using heads above 15 will not be used (as is the case with the drive in this example and also with the drive being replaced -- there is no LBA/CHS translation since the BIOS dates of these systems are from 1992 and earlier).
