This article originally appeared on Osnews.com. Recently I upgraded my home PC and I thought, well, how about loading it with only freeware/open source software (On top of Windows XP)? So I started looking around and found some excellent freeware, alongwith a lot of trash. It took some work to evaluate all the applications but in the end, it was worth it. I have nothing against Micro$oft or any other ISV making money though. It was just that I was on a tight budget and I wanted to see whether it was really possible to live without commercial software. Here is what I have settled on in the end.

The basic principle that stock markets work on is “buy low, sell high”. This works fine if you keep a close eye on the market and time your buying/selling accordingly. but this may not work in all the cases. Some people stop buying when the price starts rising, fearing that they might overpay. Others will start selling when the prices starts coming down, afraid that they might even lose whatever little profit they would be making. When you start timing the market, you might miss its best performing cycles.

PDSEs (Partitioned dataset extended) were first introduced by IBM in MVS/AFP 3.2 in the year 1989. Even though regular PDSes were quite adequate for normal tasks, many IBM customers were not happy with them. One of the IBM user groups, SHARE, did a project on MVS Storage Management and published a white paper. This paper summarized the findings of the project and asked for a number of improvements and new features to then current PDSes. Another IBM user group, GUIDE, also published their requirements and asked for similar changes. IBM listened and the result was PDSE. But first a bit of background on plain old PDS to understand its limitations.

When a VSAM file is opened by a job in the output mode, a flag in the VSAM catalog called “open-for-output” gets set to ‘ON’. This flag does not get turned off until the job ends successfully i.e. until the job closes the file normally. Or in case we are editing the file manually in file-aid, the flag gets set when we open the file and gets turned off when we close it. But say the job goes down halfway through the update process or our TSO session expires before we could close the file. The “open-for-output” flag remains turned on. What happens to the file now?

“Some books are to be tasted, others to be swallowed, and some few to be chewed and digested”.