74377

The '74377 chip (common variants 74LS377, 74HC3770 is used as a latch in mappers like Color Dreams and stores eight bits of data.

      74HC377
  Octal D flip-flop
     ,---_---.
/WE -| 1   20|- Vcc
 Q0 -| 2   19|- Q7
 D0 -| 3   18|- D7
 D1 -| 4   17|- D6
 Q1 -| 5   16|- Q6
 Q2 -| 6   15|- Q5
 D2 -| 7   14|- D5
 D3 -| 8   13|- D4
 Q3 -| 9   12|- Q4
GND -|10   11|- CLK
     `-------'

• Vcc: Connect to +5V
• GND:
• CLK: Load clock
• /WE: Write enable
• D0-7: Inputs, connected to CPU D0-D7
• Q0-7: Outputs, connected to PRG and CHR ROM address lines

D0-7 are copied to Q0-7 when CLK rises (0 to 1) while /WE is low.

References

• Philips Semiconductors. 74HC377: Octal D-type flip-flop with data enable; positive-edge trigger