🚀 go-pugleaf

	System bugs often bother users, but some have annihilated
	them.  The most amazing of such killers that I've seen
	was in the infamous Release 13 of OS/360.

	    Background for those who haven't had the "benefit"
	    of the IBM mainframe experience:

	    OS/360 provided a wondrous and "powerful" Job Control
	    Language (JCL) that allowed users to specify all sorts
	    of characteristics of their files (aka data sets) on
	    Data Definition (DD) statements.  This included niceties such
	    as the SPACE=(stuff) field, to define how much disk space
	    should be reserved initially for the file and how much
	    should space should be added when the file grew past this.

	    In fact, OS/360 REQUIRED a lot of stuff like this in
	    the DD statements for each file.  It generally took
	    3 punched cards to define a temporary (scratch) file.

	Anyway, soon after Release 13 came up at UCLA, Steve Silver
	had the misfortune of being the first user to forget to punch
	a "SPACE=" parameter for a scratch file.  Truly a serious sin
	under JCL.

	And the wages of that sin:  OS/360 trashed the disk he was using!

	Specifically, when it allocated space for this file it
	used the disk address of the VTOC (Volume Table of Contents,
	IBMese for "directory").  At this time writing his file over
	the VTOC meant losing the contents of the disk.


----------------
Paul Raveling
Rave...@isi.edu