CRT9212
CRT9212 is Double Row Buffer manufactured by SMSC.
STANDARD MICROSYSTEMS
CORPOR~irlioi NF==-
CRT 9212 f.1PC FAMILY
Double Row Buffer ORB
Features o Low Cost Solution to CRT Memory
Contention Problem o Provides Enhanced Processor Throughput for
CRT Display Systems o Replaces Shift Registers or Several RAM and
Counter IC's in CRT Display System o Permits Display of One Data Row While Next
Data Row is Being Loaded o Data May be Written into Buffer at Less Than the Video Painting Rate o Double Data Row Buffer Permits Second Data
Row to be Loaded Anytime during the Display of the Preceding Data Row o Permits Active Video on All Scan Lines of
Data Row o Dynamically Variable Number of Characters per Data Row- ... 64, 80, 132, ... up to a Maximum of 135 o Cascadable for Data Rows Greater than
135 Characters o Stackable for "Invisible Attributes" or Character Widths of Greater than 8 Bits
PIN CONFIGURATION
DIN2 1 DIN1 2 DINO 3 DOUT7 4 DOUT6 5 DOUT5 6 DOUT4 7
Vee 8 DOUT3 9 DOUT210 DOUT111 DOUTO 12
DIN713 DIN614
28 DIN3 27 WCLK 26 OE 25 WEN2 24 WEN1 23 GND 22 ROF 21 WOF 20 REN 19 CLRCNT 18 TOG 17 RCLK 16 DIN4 15 DIN5
PACKAGE 28-pin D.I.P. o Three-State Outputs o Up to 4 MHz Read/Write Data Rate o patible with SMC CRT 5037, CRT 9007, and other CRT Controllers
028 Pin Dual-In-Line Package o + 5 Volt Only Power Supply o TTL patible
GENERAL DESCRIPTION
The CRT 9212 Double Row Buffer (ORB) provides while the previous data row is being displayed. The a low cost solution to memory contention between the loading of data may take place during any of the scan system processor and the CRT controller in video dis- line times of the data row. This relaxed time-con- play systems. straint allows the processor to perform additional
The CRT 9212 ORB is a RAM-based buffer which processing on the data or service other high priority provides two rows of buffering. It appears to the sys- interrupt conditions (such as a Floppy Disk DMA tem as two octal shift registers of dynamically vari- request) which may occur during a...
