In today's competitive product environment, you can't stand still. Adding features, functionality and higher
performance has become a necessity. If you want to position your copier, scanner, printer, POS terminal, CD-ROM
drive, modem or other PC- or communications-related device at the high end of the performance scale, you need
to look at the MCS 251 microcontroller.
Intel's MCS® 251 microcontroller gives you a fast and cost-effective way to catapult your legacy MCS®
51 microcontroller-based designs into the 21st century. While moving existing MCS 51 microcontroller designs
to the MCS 251 microcontroller requires some code rewrites, the results can be breathtaking – up to a 15X
performance increase with minimal development effort.
Here are a few more reasons to consider moving up to the MCS 251 microcontroller:
Simple upgrade from MCS 51 and MCS® 151 microcontroller applications
Advanced Feature Set
The Intel MCS 251 microcontroller is a direct descendent of the classic MCS 51 architecture,
but features state-of-the-art performance and an advanced feature set. The MCS 251 microcontroller
is equipped with a register-based CPU architecture with a 40-byte register file accessible as bytes,
words and double words, for programming flexibility as well as increased performance.
Its enhanced MCS 51 microcontroller instruction set includes 16- and 32-bit arithmetic and logic instructions,
compare and conditional jump instructions, and an expanded set of move instructions that give you dramatically
enhanced performance , simpler programming and smaller code size. The MCS 251 microcontroller also features
18-bit linear code/data addressing with 256Kbyte extended stack space.
Extensive memory options are also available, including 512 byte or 1 Kbyte of on-chip data RAM or a choice of 8
or 16 Kbytes of on-chip ROM/OTPROM or ROMless options.
A Choice of Memory Options
In addition to the already advanced feature set of our MCS 251 microcontroller, Intel offers three more
versions of the MCS 251 microcontroller that provide a choice in the amounts of internal ROM/EPROM and RAM.
These members of the MCS 251 microcontroller family are the 8xC251SA, 8xC251SPand 8xC251SQ. All are based
on the high-performance MCS 251 microcontroller architecture. These advanced microcontrollers not only provide
significant performance improvements over MCS 51 microcontroller architecture, they offer you a choice of RAM
and ROM memory options, and flexible pricing options.
The 8xC251SA/SB/SP/SQ and 8xC251TA/TB/TP/TQ are binary code and pin-compatible with existing MCS 51 microcontrollers, so they
offer you the fastest and easiest way to achieve ultimate performance from your existing MCS 51 microcontroller
For high performance, the 8xC251SA/SB/SP/SQ and 8xC251TA/TB/TP/TQ share the MCS 251 controller's advanced register-based CPU
architecture and also have pipelined instruction execution units. These microcontrollers employ the powerful
MCS 251 microcontroller instruction set, with many enhanced 8-, 16- and 32-bit instructions available.
They also execute C code efficiently.
Flexible RAM, ROM/EPROM and Pricing
MCS 251 microcontrollers range in price from $5.50 to $6.50 in 100K unit direct OEM pricing for ROM products.
All are available as standard 5V 16 MHz parts and are available in commercial as well as extended temperature range.
Product options are:
8xC251SA--8K ROM/OTPROM and 1K RAM
8xC251SB--16K ROM/OTPROM and 1K RAM
8xC251SP--8K ROM/OTPROM and 512B RAM
8xC251SQ--16K ROM/OTPROM and 512B RAM
8xC251TA--8K ROM and 1K RAM
8xC251TB--16K ROM and 1K RAM
8xC251TP--8K ROM and 512B RAM
8xC251TQ--16K ROM and 512B RAM
ROMless versions are also available
8xC251SA/SB/SP/SQ: up to 16 MHz (speed)
8xC251TA/TB/TP/TQ: up to 24 MHz (speed) plus 2nd UART capability
The 8xC251 microcontrollers are available in 40-pin PDIP and 44-pin PLCC packages.
Fast and Easy Development
Intel and its third-party vendors offer a variety of hardware and software development tools to make your
MCS 251 controller development as fast as possible. Intel's ApBUILDER interactive programming software
shortens your learning curve, reduces your total design time, and speeds your migration to the
MCS 251 architecture.
To keep your edge in today's product environment, you need to look at the clear advantages of the MCS 251
microcontroller--before your competition does.