Modcomp Computer? - test-drb@ccmp.vtda.org

31 Aug 2005

On Wed, 31 Aug 2005 09:53:55 -0400, Paul Koning  
<pkoning at equallogic.com> wrote:

...
  I don't know about Modcomp, but that's not the
IBM way.  IBM had
 amazingly primitive file systems (at least through OS/360), but not
 quite *that* primitive.  You could create files at anytime, but only
 through JCL.  (Actually, I think it was possible to create files under
 program control, but not via the standard APIs.)

 [...]
     paul

You are talking about big iron here. The IBM 1800, SEL, and Modcomp  
were essentially toys which used a preallocated file system to ensure  
speed in file access. All files were guaranteed contiguous and of  
know size. The editor, compiler, and linker each had their own  
segments which they individually managed. The editor would create  
"files" within its segment. The JCL on these machines was quite  
rudimentary and did not include any capability to re-hack the file  
system. You could always design an application to partition and  
manage one of the preallocated segments.

I remember having to re-sysgen the system numerous time while we were  
designing the application in order to optimize the file sizes.

     CRC