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Part 4: Kermit

Having transferred kermit.bas from my laptop to the IBM PC, I thought I was home free. I could now run kermit on the IBM and C-Kermit on my laptop (either under Windows 11 or Fedora 43) and start transferring files.

Kermit, implemented by Columbia University, would enable proper protocol-based transfers with error correction.

Failure

The first file I wanted to transfer was MSK315M.EXE (MS-Kermit executable) from my laptop to the IBM. I started kermit on the PC, C-Kermit on the laptop, and started the transfer.

What I saw on the IBM:

Kermit showed: %%%%%
Windows showed: Retries and errors
Result: No file created on the IBM PC

The %%%%% characters indicate failed packet retries - each % represents a NAK or timeout. The file was not transferred.

What Went Wrong

Not wanting to read a bunch of BASIC code, I asked ChatGPT to read kermit.bas and tell me what was happening.

It came back and told me kermit.bas was designed to transfer text files, not binary files.

First, on line 2070 it sends N in the ACK, telling the sender "I will not do 8-bit quoting".

Second, on line 3050 it opens the output file in text mode:

3050 OPEN MID$(PKTDAT$,1,L) FOR OUTPUT AS #2

Third, on line 4040 it uses PRINT # which is text-oriented output:

4040 PRINT #2, MID$(PKTDAT$,1,P);

Fourth, on lines 7250-7270, it handles control-character unquoting but doesn't support 8th-bit quoting for high-bit characters.

Thus kermit.bas was not going to work to transfer a binary program.

Next: Part 5: Bootstrap Binary Receiver