IBM is forecast to release PC-DOS 3.4 on June 2 – and its announcement could signal the beginning of the end for the close relationship that IBM has had with Microsoft Corp ever since it chose MS-DOS for the original Personal Computer. According to Newsbytes, key features of the new PC-DOS will be a more visual user interface than any of the existing versions, and built-in extended memory support; hard disk volumes will be extended to support 512Mb of data, up from the now thoroughly constricting 30Mb limit. But, more importantly, several sources insist that IBM has bought the source code to the new release, which would mean that it would no longer have to pay Microsoft a royalty on each copy it sold. The same sources point out that the significance of IBM’s investment in Metaphor Computer Systems (CI No 911) may have been widely missed: the key development at Metaphor is a very user-friendly icon-and-mouse interface and that IBM may be considering using this instead of Presentation Manager for OS/2: Presentation Manager is due to ship in October. IBM is adding so much value in OS/2 Extended Edition that it is understood not to be paying Microsoft royalties on it. Meantime news of the new PC-DOS release further clouds the issue of when or whether developers should switch to OS/2: the supposedly more friendly user interface and the increased memory support make less important two of the key selling points for OS/2. However as far as IBM is concerned, we understand that the forthcoming PC-DOS 3.4 is intended to be the final release.