74LS89 64 BIT RANDOM ACCESS MEMORY (RAM)
with open-collector outputs
The 7489 is a high speed 64 bit RAM organized as 16-word by 4-bit array. Address inputs are buffered to minimize loading, and addresses are fully decoded inside the chip. Outputs are open collector type allowing the chip to be multiplexed with many others. When the chip is deselected the outputs go into high impedance mode allowing other chips, wired in parallel, to perform with no interference.
>Open-Collector outputs for wired-and applications
>Buffered inputs minimize loading
>Address decoding on chip
>Diode clamped inputs minimize ringing
Chips of this type still find uses in the hobbyists' world, but are largely considered outdated for general purpose functions. Possibly the best use for this chip would be for the use of simple high speed lookup charts or customizable decoder logic, however due to the volatility of the memory, power must be properly maintained to ensure storage of the data within.