place with delays compatible with the speed of the TV raster, i. 
e. not greater then 100 nsec.. 
The delay problems have been solved by using some specific 
fast components available today on the market which have given us 
the possibility of preserving the time dependent characteristics 
of the design. 
The overall system, which has been realised, requires a D/A 
conversion between the computer and the SCM, and a double A/D - 
D/A conversion between the SCM and the TV display screen (see 
block diagram in fig. 1). 
An alternative system in which the false colour conversion me- 
chanism takes place in analogic form, under the control of digital 
memories has also been implemented (see block diagram in fig. 23. 
This last scheme presents the major advantage of giving, 
practically, an illimited resolution capability within any scale 
of coding in false colours. 
In the following we will briefly describe the block diagram 
components of the two schemes. 
System in fig. 1 
The function of the blocks 1, 2 and 3 is quite obvious, since 
they constitute the interface between the computer and the SCM, 
used in trasferring the image data stored in digital form. 
The block 4 is the A/D parallel converter built in our labora- 
tory. For this device we have used very fast component in order to 
have a conversion time of 40 nsec.. This is a 4 bits prototype 
which allows an image coding with 16 levels of grey. The next 
prototype will provide more bits in output. 
At each conversion step one of the 16 combinations available 
from the ADC output, driven by a 10Mc clock (block 5), 1s used as 
the address of a location memory in a RAM (blocks 6, 7, 8) with an 
    
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
    
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