THE INSTRUCTION SET

RRC

(Rotate right)

(An) - (An + 1); (A7) - (Ao) (CY) - (Ao)

The content of the accumulator is rotated right one position. The high order bit and the CY flag are both set to the value shifted out of the low order bit position. Only the CY flag is affected.

o o o 0 1

Cycles: 1

States: 4

Flags: CY

RAL(Rotate left through carry) (An+ 1)-(An);(CY)-(A7)

(Ao)-(CY)

The content of the accumulator is rotated left one position through the CY flag. The low order bit is set equal to the CY flag and the CY flag is set to the value shifted out of the high order bit. Only the CY flag is af· fected.

o o o 1 o 1 1

Cycles: 1

States: 4

Flags: CY

RAR(Rotate right through carry)

(An) - (An + 1);(CY) - (Ao) (A7) - (CY)

The content of the accumulator is rotated right one position through the CY flag. The high order bit is set to the CY flag and the CY flag is set to the value shifted out of the low order bit. Only the CY flag is affected.

o o 1 1 1 1 1

Cycles: 1

States: 4

Flags: CY

CMA

(Complement accumulator)

(A) - (A)

The contents of the accumulator are com- plemented (zero bits become 1, one bits become 0). No flags are affected.

 

o

o

1

o

1

1

1

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cycles:

 

1

 

 

 

 

 

 

 

States:

 

4

 

 

 

 

 

 

 

Flags:

 

none

 

 

 

 

CMC

 

(Complement carry)

 

 

 

 

(CY) -

(CY)

 

 

 

 

 

 

 

The CY flag is complemented. No other

 

flags are affected.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

o

o

 

1

1

1

1

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cycles:

 

1

 

 

 

 

 

 

 

States:

 

4

 

 

 

 

 

 

 

Flags:

 

CY

 

 

 

 

STC

 

(Set carry)

 

 

 

 

(CY) - 1

The CY flag is set to 1. No other flags are affected.

o o 1 1 0 1 1 1

Cycles: 1

States: 4

Flags: CY

*AII mnemonics-copyrighted-©lnteLCorporatiqn j976.

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Intel MCS-80/85 manual Cma, Cmc, 1 1 1 1
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MCS-80/85 specifications

The Intel MCS-80/85 family, introduced in the late 1970s, is a seminal collection of microprocessors that played a pivotal role in the early days of computing. The MCS-80 series, initially targeting embedded systems and control applications, gained remarkable attention due to its innovative architecture and flexible programming capabilities.

The MCS-80 family is anchored by the 8080 microprocessor, which was one of the first fully integrated 8-bit microprocessors. Released in 1974, the 8080 operated at clock speeds ranging from 2 MHz to 3 MHz and featured a 16-bit address bus capable of addressing up to 64KB of memory. The processor’s instruction set included around 78 instructions, providing extensive capabilities for data manipulation, logic operations, and branching.

Complementing the 8080 was a suite of support chips, forming the MCS-80 platform. The most notable among them was the 8155, which integrated a static RAM, I/O ports, and a timer, tailored for ease of designing systems around the 8080. Other support chips included the 8085, which provided improvements with an integrated clock generator, making it compatible with more modern designs and applications.

The MCS-85 series, on the other hand, revolves around the 8085 microprocessor, which provided a more advanced architecture. The 8085 operated at clock speeds of up to 6 MHz and came with a 16-bit address bus, similar to its predecessor. However, it introduced more sophisticated features, including an enhanced instruction set and support for interrupt-driven programming. These enhancements made the 8085 especially appealing to developers working in real-time processing environments.

The MCS-80/85 family utilized NMOS technology, known for its lower power consumption and higher performance compared to previous technologies like TTL. The family’s architecture allowed for easy interfacing with a variety of peripherals, making it a favorite for educational institutions and hobbyists embarking on computer engineering projects.

With its robustness, versatility, and affordability, the Intel MCS-80/85 microprocessors laid the groundwork for many subsequent microcomputer systems and applications. The legacy of this powerful family continues to influence modern microprocessor design, emphasizing the importance of reliable architecture in a rapidly evolving technology landscape.
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