Intel 8253

The Intel 8253 is a programmable Zähler-/Zeitgeber-Baustein (Programmable Interval Timer, PIT), which was primarily developed for the Intel-8080/8085-Prozessor. Later, the chip was also used together with the Intel 8086/8088 and its successors. The block is mainly supplied in 24-pin DIP. He was licensed to, inter alia, Mitsubishi Electric, National Semiconductor, NEC and Siemens. It has been used for the first computer (IBM PC, and the IBM PC XT). The 8254 as a slightly improved version was used in the IBM PC AT.


The 8253 contains three independently operating 16 -bit counter that can operate down to count frequency of 2 MHz. The different operating modes can be set via the software of the microcomputer system.

Literature and data sheets

  • Microcomputer modules, Data Book 1979/80, Volume 3, peripherals, Siemens AG, No. B 2049, pp. 102-123.
  • NEC Electronics (Europe) GmbH, 1982 Catalog, pp. 649-656.
  • Intel's documentation for the 8254 chip ( PDF; 302 KB)