EGA and up handles this by beefing up hardware support for read-modify-write operations and setting/unsetting bits in bulk, eg. you can XOR 8 pixels with a bit

EGA and up handles this by beefing up hardware support for read-modify-write operations and setting/unsetting bits in bulk, eg. you can XOR 8 pixels with a bit pattern on three out of four planes simultaneously with a single memory write.