dynamic disk overlay

Well, you don't get documentation anymore.I found this from 1995 DM.HLP: DDO An Ontrack software driver that eliminates limitations of a system's BIOS and allows installation of large drives that could otherwise not be installed to full capacity. See the Online Manual for a complete description of the Dynamic Drive Overlay and related topics. Initially, the Dynamic Drive Overlay always loads into the top of conventional memory and reduces the amount of memory for DOS. However, before you get a DOS prompt, the Dynamic Drive Overlay will attempt to relocate itself in one of the following ways: If you are using EMM386.EXE and have DOS=UMB set in CONFIG.SYS, the Dynamic Drive Overlay can load into UMBs if there is a 5K block available. All but 80 bytes of the conventional memory originally occupied by the Dynamic Drive Overlay is returned to DOS. If you are not using a memory manager, the Dynamic Drive Overlay will remain in conventional memory and will insert itself into the DOS memory chain. DOS will again see all memory in the system (5K of this will be used by the Dynamic Drive Overlay). If you are using a memory manager other than EMM386.EXE, the Dynamic Drive Overlay may be unable to relocate or insert itself into the memory chain. In this case the amount of conventional memory remains reduced by about 6K. Well, Google has gotta have more info. May not apply anymore, even back then: "it was everywhere" Getting between the OS and the drives. ******************************************** Best

if you are asking where on the hdd, MY understanding it starts at head 0 cyl 0 setor 1 , overwriteing MS's MBR, do not know how many sectors it takes. I would guess the drive would have to be the boot hdd ,not a slave and if you use a boot floppy DOS will not see the hdd correctly, due to the hdd's MBR not being read into memory as post #1.

Even with boot from Floppy I can see the HDD correctly. Thank you.

Hi Good answers above. You state you can boot from floppy and see the drive. This floppy is just an ordinary boot floppy and not one created for your system? If any floppy that has just had only the system file transfered, eg sys command (or a downloaded boot disk), can boot and see the entire harddrive, then there is no DDO installed.

Yes. Boot from floppy starts after DDO is loaded, infact, Ontrack DDO asks if you want to boot from floppy.

"Even with boot from Floppy I can see the HDD correctly." Then you do not need overlay of the drives. Are you sure you can see the entire drive? The purpose was stated above. The old limit was 7.8 GB and still is with many tools. If you can see drives then you don't need DDO. Best