There is the possibility that your CMOS settings have corrupted. They affect the ability to read the hard drive, floppy drive and control the keyboard test which when turned OFF allows the use of the smaller EZTRAK keyboard.
There is the possibility that a virus has destroyed your hard drive boot sector. Typically the old DOS viruses were aimed at that. It is impossible to run a virus scan on these machines because 4 MB of RAM is not enough to load and run a virus scan. Usually I have to format and transfer the system to a floppy and then take the floppy to a good PC with the latest antivirus software and scan it to see if a virus exists. Typically the DOS viruses are written to jump to a floppy when one is created especially a boot floppy.
The older versions of the EZTRAK software up to version 3.02 would look for a hard drive and if one is not found would create a RAM DISK in memory. This to accomodate the SX machine versions that did not have a hard drive.
I can send you a self extracting zip file that when extracted to a floppy would give you a good disk that will load the software. It will have a EXE extension, so most firewalls will stop it. This will not help if you have a virus. You will need to format the drive to erase the virus and then load DOS 6.20 and then the software. BTW, I usually keep all my disks locked to prevent a virus jumping to them.
I need your email address.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)