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from PC to Intel Intellec MDS
ISIS Operating System

11 Jan 2018

Kermit transfer from PC to Intel Intellec MDS ISIS Operating System Click images for larger view

Using a special ISIS version of the Kermit transfer program, it's possible to transfer files from a Windows PC to the Intel Intellec MDS computer. This gives the MDS computer owner access to a wide range of programs, files and tools that are archived around the internet.

My MDS runs OSIRIS which is a variation of the ISIS/ISIS-II operating system from Intel. I believe these instructions will work for both of those systems.

Thanks to Mark, Bill, Jack, Herb, Eric, Jon, John, Randy and others on the informal Intel MDS mail group.

Get TeraTerm Working to the MDS

Get TeraTerm running on the Windows PC. This gives you an RS232 terminal interface to the MDS.

It's best to use a real serial port on the PC, although the USB-RS232 converters might work also.

The cable will have a female 9 pin connector on the PC side (DE9) and a male 25 pin connector on the MDS side (DB25).

PC to MDS cable

DE9 Female      DB25 Male
   2 <------------ 3  data
   3 ------------> 2  data
   5 ------------- 7  ground

Setup your MDS for 300 baud. This takes changing a hardware jumper on the Monitor card. See the MDS docs, which are WRONG! :) You'll have to experiment. Set TeraTerm to the same parameters 300-N-8-1 and you should be able to use the PC as a terminal to the MDS. In the Keyboard Setup menu, click 'Backspace' in the DEL box to make backspace work with ISIS. Don't go further until you have this working.

Transfer Kermit to the MDS

Now download the first half of the Kermit program, and the second half to your PC. These 2 files combined are the complete kermit program in Intel hex format. You can view them with a text editor.

Boot up your MDS and get a TeraTerm session going. In the Serial Port Setup menu, set serial port parameters to 300 baud, no parity, 8 data bits, 1 stop bit, character delay to 20ms and line delay to 500ms.

This example uses the :F1: floppy drive, :CI: is Console Input. To transfer the first half of Kermit, type this on the MDS then press ENTER/RETURN:


Now start sending the file by selecting SEND from TeraTerm's FILE menu and selecting the KERM1 file. When it's done, type CTRL-Z to mark End of File. You'll hear the floppy disk clunk and the file will be written.

Next, do the same thing for KERM2.
File sizes are 29910 for KERM1 and 38121 for KERM2.
After this you will have 2 file halves on the MDS, join them with this command:


Memory Note:
This works on my system with 64K RAM. If your MDS has less memory, you might have to split up Kermit into 4 pieces. Do that with a text editor and make sure each file ends at the end of a line followed by one CR.

KERMIT.HEX should be 68031 bytes.
Now convert the hex file into a binary object file with:


The HEXOBJ program is a common tool on MDS machines. If there are no error messages, you likely have a good conversion. Scream WOOHOO because you have now opened your MDS system up to the world.

Transfer Files using Kermit

Now that Kermit is transferred, you can change your baud rate back to 9600 on the MDS and on TeraTerm.

You're ready to run Kermit with:


You'll get a blob of random characters because this version of Kermit changes the MDS's serial port baud rate divider to /4 instead of /16. In TeraTerm, change the baud rate to 38k which is 4x what the MDS WAS set at. You should get a '-' prompt after hitting Enter.

Look at parameters:


Set the default drive to :F1:


See Help instructions:


Now begin receiving a file:


Kermit is ready to receive a file, so go to TeraTerm's FILE menu and select TRANSFER, then KERMIT, then SEND, then select a file. You'll get a progress box and the file is on its way. It's very slow but it's very reliable and is checking each packet. I got a total of about 15 characters a second, regardless of the baud rate. In the file selector dialog box, you can select multiple files then go to dinner. EXIT gets you back to ISIS.

ISIS file names are limited to 6 dot 3. Selecting an 8 dot 3 file will just stall.

Boot Files, Disk Images, etc

This method obviously only transfers files to a system with a working operating system. Writing boot sectors and entire disk images is another story for another project page.

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