MCS-48

The MCS-48 microcontroller (µC) series, Intel's first microcontroller, was originally released in 1976. Its first members were 8048, 8035 and 8748. Initially this family was produced using NMOS-technology, in the early 1980s it became available in CMOS-technology. It was still manufactured into the 1990s to support older designs that still used it.

The MCS-48 series has a modified Harvard architecture, with internal or external program ROM and 64–256 bytes of internal (on-chip) RAM. The I/O is mapped into its own address space, separate from programs and data. The 8048 is probably the most prominent member of Intel's MCS-48 family of microcontrollers.

Though the MCS-48 series was eventually replaced by the very popular MCS-51 series, even at around year 2000 it remained quite popular, due to its low cost, wide availability, memory-efficient one-byte instruction set, and mature development tools. Because of this, it is much used in high-volume consumer electronics devices such as TV sets, TV remotes, toys, and other gadgets where cost cutting is essential.

The 8049 has 2 KB of masked ROM (the 8748 and 8749 had EPROM) that can be replaced with a 4 KB external ROM, as well as 128 bytes of RAM and 27 I/O ports. The µC's oscillator block divides the incoming clock into 15 internal phases, thus with its 11 MHz max. crystal one gets 0.73 MIPS (of one-clock instructions). Some 70% of instructions are single byte/cycle ones, but 30% need two cycles and/or two bytes, so the raw performance would be closer to 0.5 MIPS.

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