| 摘要 |
A process is disclosed for retrieving data from a database stored in a fixed disc 3 for display on the screen of a VDU 6 or printing at a printer 9. Fields in each retrieved database record are stored in a RAM 4 in the form of a virtual screen 41 which is similar to a screen layout for the VDU 6 except that physical constraints are not taken into account up to preset large dimensions, in this case 256 rows, each having 256 character locations. Blocks 44 within the virtual screen 41 are selected for display to give the effect of a window or viewport on the virtual screen 41. Versatility in security of data fields is achieved by comparisons between a user security level and a separate security level value for each individual field. According to the comparison, a control unit 2 selects which fields are written to a screen memory 8 or printed and which may be written to in the RAM 4. <IMAGE> |
