495 
There still remains 1/0 procedure between the shared disks and FEP,BEP. 
In order to shorten this [//0 time FORTRANT7 and FORTRAN77/VP provide the high 
speed 1/0 processing. This function is illustrated in Fig.5. In this case 
the array data on the main memory is transferred to three disks concurrently 
without 1/0 buffers. The parallel file access method divides automatically 
the array data according to the number of allocated disks. In our case, two 
disks are used to process SAR data. So, the 1/0 speed becomes twice as fast as 
the I/0 speed in the case that only one disk is used. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
  
  
  
  
  
ARRAY DISK 1 
BLOCK 1 D e a 
ax rennes | 
où: RM 
BLOCK N-2 J DISK 3 
BLOCK N-L J 
BLOCK N € 
BLOCK N 
PARALLEL FILE 
FIG, 5 HIGH SPEED 1/0 PROCESSING