linked directly by means of interfaces, or indirectly via intermediate 
recording and retrieval of information. Mixed solutions are also possible 
(table 4). 
  
  
  
  
  
  
LINK MAIN PROCESS STAGE 
Collection Processing Presentation 
On-line (real-time) on | on 
Off-line (delayed) off | off 
Partly on-line on | off 
Partly off-line off | on 
Table 4: Links between process stages. 
The most pertinent variants are the second ("off-off") and the third 
("on-off" connections). 
2. Equipment 
À suitable way of classifying the equipment components is according to 
the main process stages, though some components can be common (figure 1). 
Graphic line 
digitiser 
Mono-(stereo) 
Existing comparator 
components Raster scanners/ 
digitiser 
Collection Interactive 
  
terminal(s) 
— E xis digitising 
Dedicated X,y,px digitising 
Dedicated [- Graph-image overlay 
Computer/microprocessor(s) 
Processing —| Standard peripherals 
Interactive terminal(s) 
  
Equipment 
  
Interactive terminal(s) 
  
Presentation Communication network(s) 
Communication Drafting machines 
Printers 
Fig. l: Equipment components. Other devices 
The components can be linked in different ways. Figure 2 shows an ex- 
tended architecture of a stand alone (off-line) AMP system. The display 
terminals and the sub-system for graph-image overlay are optional. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Measuring/ Graphic-image 
digitising =- —| overlay ss — ri ot 
unit sub-system | 
AN Keyboard | Magnetic = A | 
terminal Microprocesso "ldisk/tape " Graphic | 
unit terminal 
1 t | 
Standard | Host xd 
eripherals Computer Data base|— 
i 
Drafting 
machine 
  
  
  
Fig. 2: Stand alone AMP system (extended). 
30