whitespace
authorLuke Kenneth Casson Leighton <lkcl@lkcl.net>
Tue, 31 Mar 2020 10:49:49 +0000 (11:49 +0100)
committerLuke Kenneth Casson Leighton <lkcl@lkcl.net>
Tue, 31 Mar 2020 10:49:49 +0000 (11:49 +0100)
openpower/isans_letter.mdwn

index 5d9d313de0b3729a680eff5166be02ff4aa714fa..81f7379dbbbae59d83c83f5e2043eb96d887e9db 100644 (file)
@@ -1,53 +1,53 @@
 (Draft Status)
 
-# Letter regarding ISAMUX / NS                                                                                         
-                                                                                                                       
-This is a quick overview of the changes that we are proposing to the PowerPC                                           
-instruction set.                                                                                                      
-                                                                                                                      
-## Overview                                                                                                           
-                                                                                                                       
-The PowerPC Instruction Set Architecture (ISA) is an abstract model of a                                              
-computer. This is what programmers use when they write programs for the machine,                                      
-even if indirectly via a compiler for a high level language. We must be                                               
-conservative in how we add to the ISA to:                                                                             
-                                                                                                                      
-* not break existing programs                                                                                           
-                                                                                                                      
-* be mindful as to how others may wish to add to the ISA in the future                                                
-                                                                                                                      
-This document describes our strategy.                                                                                  
-                                                                                                                      
-                                                                                                                      
-## ISA modes and escape sequences                                                                                     
-                                                                                                                      
-New chips usually need to be able to run older (legacy) software that is                                               
-incompatible with the latest and greatest ISA. Eg: 64 bit chip must be able to                                        
-run older 16 bit and 32 bit software.                                                                                 
-                                                                                                                      
-To enable backwards compatability the CPU will be set into 'legacy' mode. This                                        
-is done with an ISA Mode switch, also known as ISA Muxing or ISA Namespaces.                                          
-                                                                                                                       
-The operating system is able to quickly change between 'modern' ISA mode and                                          
-various legacy modes.                                                                                                 
-                                                                                                                      
-Another technique is an ISA escape-sequence. This is a type of mode that is                                           
-only operational for a short time, unlike 32 or 64 bit which would be for the                                         
-entire run of a program.                                                                                              
-                                                                                                                       
-                                                                                                                      
-## What are we adding to the ISA                                                                                      
-                                                                                                                      
-When high quality graphical display were developed the CPUs at the time were                                          
-shown to not be able to run the display fast enough. The solution was the use of                                       
-Graphics cards, these are specialised computers that are good at rendering                                            
-pixels; often by doing the same thing in different parts of the screen at the                                         
-same time (in parallel). These specialised computers are called Graphical                                             
-Processing Units (GPUs).                                                                                              
-                                                                                                                      
-The parallelism of some GPUs is thousands. This has led to GPUs being used to                                         
-solve non graphical problems where high parallelism is useful.                                                        
-                                                                                                                      
+# Letter regarding ISAMUX / NS      
+      
+This is a quick overview of the changes that we are proposing to the PowerPC     
+instruction set.    
+     
+## Overview  
+      
+The PowerPC Instruction Set Architecture (ISA) is an abstract model of a 
+computer. This is what programmers use when they write programs for the machine,
+even if indirectly via a compiler for a high level language. We must be  
+conservative in how we add to the ISA to:  
+     
+* not break existing programs           
+     
+* be mindful as to how others may wish to add to the ISA in the future   
+     
+This document describes our strategy.       
+     
+     
+## ISA modes and escape sequences  
+     
+New chips usually need to be able to run older (legacy) software that is  
+incompatible with the latest and greatest ISA. Eg: 64 bit chip must be able to  
+run older 16 bit and 32 bit software.      
+     
+To enable backwards compatability the CPU will be set into 'legacy' mode. This  
+is done with an ISA Mode switch, also known as ISA Muxing or ISA Namespaces.    
+      
+The operating system is able to quickly change between 'modern' ISA mode and    
+various legacy modes.       
+     
+Another technique is an ISA escape-sequence. This is a type of mode that is     
+only operational for a short time, unlike 32 or 64 bit which would be for the   
+entire run of a program.    
+      
+     
+## What are we adding to the ISA   
+     
+When high quality graphical display were developed the CPUs at the time were    
+shown to not be able to run the display fast enough. The solution was the use of 
+Graphics cards, these are specialised computers that are good at rendering      
+pixels; often by doing the same thing in different parts of the screen at the   
+same time (in parallel). These specialised computers are called Graphical
+Processing Units (GPUs).    
+     
+The parallelism of some GPUs is thousands. This has led to GPUs being used to   
+solve non graphical problems where high parallelism is useful.   
+     
 **break**
 
 # Letter regarding ISAMUX / NS