View msm82c53-5rs datasheet:

MSM82C53-5RS (1/2) IL00 ********** C-MOS PROGRAMABLE INTERVAL TIMER —TOP VIEW— 1 2 3 4 5 6 7 8 D7 I/O 1 VDD 24 D7 D6 D5 D4 D3 D2 D1 D0 (+3 to +6V) 9 10 CK 0 OUT 0 D6 I/O 2 23 WR IN 11 GATE 0 D5 I/O 3 22 RD IN 15 13 CK 1 OUT 1 14 GATE 1 D4 I/O 4 21 CS IN 18 17 CK 2 OUT 2 D3 I/O 5 20 A1 IN 16 GATE 2 D2 I/O 6 19 A0 IN A1 A0 WR RD CS 20 19 23 22 21 D1 I/O 7 18 CK 2 D7 - D0 ; 8-BIT DATA I/O D0 I/O 8 17 OUT 2 CK N ; COUNTER CLOCK GATE N ; COUNTER GATE CK 0 9 16 GATE 2 OUT N ; COUNTER OUTPUT OUT 0 10 15 CK 1 RD ; READ COUNTER WR ; WRITE CMD OR DATA GATE 0 11 14 GATE 1 CS ; CHIP SELECT A1, A0 ; COUNTER SELECT 12 GND 13 OUT 1 FUNCTION TABLE INPUTS FUNCTION CS RD WR A1 A0 0 1 0 0 0 Load Counter No. 0 0 1 0 0 1 Load Counter No. 1 0 1 0 1 0