Try to use DR Dos system floppy booting and SYS to your new made HDD

check the link in this topic --your need to meet HW condition

edijuh

Update. I used DD rescue to make a bit for bit copy of the original 170m hard drive to a 250mb hard drive. When I try to boot from the new drive, I get a "missing operating system" error. How is this possible on a bit for bit copy? It seems like there's some siemens copy protection going on. This is an older machine. Maybe the older machines HD's cant be copied? Anyone ever successfully copy an older 840C drive before? 

All the files are on the duplicated drive. 

 Here we are talking about Siemens 840C, but actually is PC HW and SW tech. Not really Siemens !

However, I think you need try to use old PC and old OS system for the old Siemens System.

e.g. try to meet HW and OS condition in the link related for this topic (i will post it here, Thanks Pee for share!!)

PS: Did you try under Win 10 "Win Image ". I recently colon other OEM (Non_Siemens) HDD and USB

working OK

edijuh

Tried to make a clone with clonezilla and it gives a different error. "cannot load file". Thats using the original 170meg drive for the source. 

 Which country are you working . I am in North America , and I talked to you Clone or image the disk is tech. of PC skills , whenever I meet problem I will look for my local PC shop "expert", I know not every "expert"  is really as they said. But after many times try I found a close Friend , he is really helpful.

He does not know Siemens , every time I will bring my demo to him and show him what is the good and bad...., he normally 99.9% can let me satisfied , and sure I need pay him.

If you have hard time to find really experts in your homeland. PM me , i may help you to do it. only things you need is time or money  

edijuh

I was able to find an 840C floppy for cheap. Now I need the  6FC9 344-5G cable. Searching the web, seems like there is not one available on the planet earth. Where is the pinout information for this cable? I found a siemens manual on 840C peripherals but no wiring diagram or even any indication in the manual as to where the cable actually  plugs  into the MMC. 

You are right. here in Canada, I found couple of customers updated their HDD to SSD before the system broken down by Siemens services or by me or my partner