R6545AP

DESCRIPTION 
The R854S/R8545E CRIT Controller (CRTC) intertaces an 8-bit mlicroprocessor to CRT raster scan video displays, and adds anadvanced CRT controller to the established and expanding line of R6500,R8500/"and R6SC00 microprocessor, microcomputer and peripheral device products.
The A6545 and R6545E devices differ only in the character clock frequency (CCLIK) specifications. The maximum CCLK frequency is 2.5 MHz for the R6545 and 3.7 MrHz for the R6545E. Through out this document, the nomenclature R6545 applies to both devices, unless specified otherwise.
The R8545 provides refresh memory addresses and character generator row addresses which allow up to 16K charactars with 32 scan lines per character to be addressed.A major advan tage of the R6545 is that the refresh memory may be addressed in oither straight binary or by row/column.
Other tunctions in the R6545 include an internal cursor register which generates a cursor output when its contents are equal to the current refresh address. Programmable cursor start and end registers allow a cursor of up to the full character scan in height to be placed on any scan lines of the character. Varlable cursor display blink rates are provided.A light pen strobe input allows capture of the current refresh address in an internal light pen register. The retresh address lines are conligured to prvide direct dynamic memory refresh.
All timing for the video refresh memory signals is derived trom the character clock input (CCLK). Shift register, latch, and multiplex control signals (when needed) are provided by extermal high-speed timing. The mode control register alows noninter laced video display modes at 50 or 60 Hz refresh rale. Theinternal status register may be used to monitor the A6545 operation. The RES input alows the CRTC-generated field rate to be dynamically-synchronized with line trequency jitter.

FEATURES
· Compatible with 8-bit microprocessors
·3.7 MHz character clock operation (R6545E)
·2.5MHz character clock operation (R6545)
· Refresh RAM may be configured in row/column or straight binary addressing
· Alphanumeric and limited graphics capablity
· Up and down scroling by page, line, or character
· Programmable vertical sync width
· Fully programmable dieplay frows, columns, character matritx)
· Video display RAM may be configured as part of microprocessor memory field or independently slaved to R6545(Transparent Addressing)
· Interiaced or non-interlaced scan
· 50/60 Hz refresh rate
· Fully programmable cursor
· Light pen register
· Addresses refresh RAM to 16K characters
· No extermal DMA required· Internal status register
·40-plin ceramic or plaetic DIP
· Pin-compatible with MC6845R
· Single+5±5% Vdc power supply