GENERAL DESCRIPTION
The MSM6404A microcontroller is a low-power device implemented in complementary metal oxide semiconductor technology. The MSM6404A is optimized for high-speed processing and complicated-control applications.
The MSM6404VS is a CMOS 4-bit microcontroller that employs an external EPROM using a piggy-back package in place of the program memory (ROM) internal to the MSM6404A.
The MSM6404VS can be used for program development verification because the programs can be modified by programming an external EPROM 2732 equivalent or 2764A equivalent.

FEATURES
• Mask ROM (MSM6404A) : 4000 words X 8 bits
   External ROM (MSM6404VS) : 8196 words X 8 bits
• RAM (including the stack area) : 256 words X 4 bits
• I/O port
      Input-output port : 8 ports X 4 bits
      Input port : 1 port X 4 bits
   4 bits are for input ports having a latch; the other 32 bits are input/output ports that allow bit manipulation
• Three built-in counters : 12-bit time-base counter
                                12-bit programmable timer
                               8-bit high-speed programmable timer/event counter
• Built-in 8-bit serial I/O register (with 3-bit counter)
• Five interrupts with five priority levels (4 internal, 1 external)
• 32 stacks (in RAM)
• Power-down features
• Minimum instruction execution time : 952 ns @ 4.2 MHz clock
• Instruction systems suitable for control
• Fully static operation
• Low power consumption
• Single 5 V supply
• Package options:
   MSM6404A
      42-pin plastic DIP (DIP42-P-600-2.54) : (Product name : MSM6404A-XXXRS)
      44-pin plastic QFP (QFP44-P-910-0.80-K) : (Product name : MSM6404A-XXXGS-K)
      44-pin plastic QFP (QFP44-P-910-0.80-2K) : (Product name : MSM6404A-XXXGS-2K)
   MSM6404VS
      42-pin ceramic piggyback (ADIP42-C-600-2.54) : (Product name : MSM6404VS)
                                                            xxx indicates a code number.