GENERAL DESCRIPTION

The SAA5355 FTFROM (Five-Two-Five-ROM) is a single-chip VLSI NMOS crt controller capable of handling the display functions required for a 525-line, level-3 videotex decoder. Only minimal hardware is required to produce a videotex terminal using FTFROM - the simplest configuration needs just a microcontroller and 4 Kbytes of display memory.

Features

• Minimal additional hardware required

• Screen formats of 40/80 character by 1-to-25 row display

• 512 alphanumeric or graphical characters on-chip or extendable off-chip

• Serial attribute storage (STACK) and parallel attribute storage

• Dynamically redefinable character (DRCS) capability over full field

• Interfaces with 8/16-bit microprocessors with optional direct memory access

• On-chip scroll map minimizes data to be transferred when scrolling

• 32 on-screen colours redefinable from a palette of 4096

• Three on-chip digital-to-analogue converters which compensate for crt non-linearity

• Memory interface capable of supporting multi-page terminals. FTFROM can access up to 128 Kbytes of display memory

• Programmable cursor

• Programmable local status row

• Three synchronization modes:

stand-alone built-in oscillator operating with an external 6,041957 MHz crystal

simple slave directly synchronized from the source of text composite sync

phase-locked slave indirect synchronization allows picture-in-text displays (e.g. VCR/VLP video with text overlay)

• On-chip timing with composite sync output

• Zoom feature which allows the height of any group of rows to be increased to enhance legibility