• Please review our updated Terms and Rules here

IBM 5155 - "Insufficient memory to run"?

Hugo Holden

Veteran Member
Dec 23, 2015
For my own 5155, (since I'm not very cluey about file transfers via the ports in DOS, though its easy with my SOL-20 with CP/M it seems with PCPUT & PCGET via the serial port) and I'm better with the hardware side of things than any software, I decided the easiest thing to do was to install a dual 3.5/5.25 floppy drive in one bay of my 5155, with the "Unique floppy controller board" and an vintage Seagate HDD in the other bay. My computer also has the AST 6 pack plus card and the smaller IBM isa memory card too to get 640kb.

On the HDD I have DOS 3.3 and a number of other programs I use such as IBM's assembler and the usual DOS utilities and various other programs as there is plenty of space on the HDD. Also I put Windows V1.0 on it and Harvard Graphics. DOS 3.3 was the first version to support the 1.44Mb floppy. Also I have Procom for terminal emulation and Borland's Brief as a text editor to write assembly programs. So its all very handy having it right there on the HDD.

But the convenient thing is I have an external 1.44 floppy drive on my other more modern computers so I can easily get files, programs & data etc in & out of the 5155 that way.

There will be better ways to do it via the ports, but this hardware way "worked for me" and I have little trouble with it. The 5155 is not original though, but the two belt drive original IBM floppy drives might not have been wonderful either. I keep these with the computer & the original controller card, just in case one day I want to put it back to original. The power supply in the 5155 is up to running the HDD.

It was an interesting process to fit the HDD, it requires a low & high level format and I had to try a couple before I found a good drive unit, but it has been reliable for a couple of years now.

One thing I learnt the hard way was that the cheap external 1.44Mb USB floppy drives coming out of the far east are often really bad and corrupt files. I would advise buying something like a 1990's to 2005 vintage new old stock brand like IBM or Imation drive in its original box, cost more, but you won't have any troubles. I struggled for some weeks trying to work out why the programs I transferred via one of the cheap drives were corrupted. I only found it because I had jpeg images on a disk in the cheap 1.44 drive and noticed over time the pixels in the image were becoming corrupted, without that visual indication, I would probably still be working on it trying to find out what the heck was wrong.
Last edited: