From: ldo@nz.invalid   
      
   On Thu, 1 May 2025 18:56:39 -0400 (EDT), Scott Dorsey wrote:   
      
   > It's a weird thing... it's an I/O machine that happens to have a CPU   
   > controlling it.   
      
   That’s a mainframe in a nutshell.   
      
   > It's a very different way of thinking about computing and it's still a   
   > good thing for transaction processing systems with big databases behind   
   > it, the sort of thing that is I/O intensive but cannot be easily   
   > distributed.   
      
   It’s an obsolete way of thinking about computing. It dates from a time   
   when the CPU was considered a scarce, expensive resource, so all these   
   elaborate “channels” were added to offload as much I/O processing as   
   possible, to reduce the bother on the CPU.   
      
   The result was high I/O throughput, at the expense of high latency when   
   responding to events, such as user actions. They were a lousy match for   
   the model of interactive timeshared computing that became popular on the   
   minicomputers from DEC and other vendors, from about the 1960s onwards.   
   That new model was seen as “wasteful” by some, but the increase in   
   productivity of users made it very popular, and the cheaper (non-IBM)   
   hardware made it more economic.   
      
   The logical conclusion was the microprocessor-based single-user PC, which   
   spent >99% of its CPU cycles waiting for the user to press a key or click   
   a mouse -- the ultimate in waste, but also the ultimate in productivity.   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)