Cmake have a bunch of generators for different command line tools ( https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html ) so user/developer can use their preferred generator instead of relying only on GNU Make ( especially on windows machine )

So the README.md should contain information about the same and remove GNU make as a mandatory dependency.

create issue templates for "add tests for ..." and "implement ... instructions" issues.

it would save me a lot of time.

currently the only way to write memory is using the subscripting operator "[]", we still need a way to write program to memory maybe from a file.

instructions that involve manipulating data in by performing some arithmetic or logical operations on it.

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Instructions to handle different kinds of interrupts in processor

opcodes

      MOV_AA = 0x7F,
      MOV_AB = 0x78, MOV_AC = 0x79, MOV_AD = 0x7A, MOV_AE = 0x7B, MOV_AH = 0x7C,
      MOV_AL = 0x7D, MOV_AM = 0x7E,

      MOV_BA = 0x47, MOV_BB = 0x40, MOV_BC = 0x41, MOV_BD = 0x42, MOV_BE = 0x43,
      MOV_BH = 0x44, MOV_BL = 0x45, MOV_BM = 0x46,

      MOV_CA = 0x4F, MOV_CB = 0x48, MOV_CC = 0x49, MOV_CD = 0x4A, MOV_CE = 0x4B,
      MOV_CH = 0x4C, MOV_CL = 0x4D, MOV_CM = 0x4E,

      MOV_DA = 0x57, MOV_DB = 0x50, MOV_DC = 0x51, MOV_DD = 0x52, MOV_DE = 0x53,
      MOV_DH = 0x54, MOV_DL = 0x55, MOV_DM = 0x56,

      MOV_EA = 0x5F, MOV_EB = 0x58, MOV_EC = 0x59, MOV_ED = 0x5A, MOV_EE = 0x5B,
      MOV_EH = 0x5C, MOV_EL = 0x5D, MOV_EM = 0x5E,

      MOV_HA = 0x67, MOV_HB = 0x60, MOV_HC = 0x61, MOV_HD = 0x62, MOV_HE = 0x63,
      MOV_HH = 0x64, MOV_HL = 0x65, MOV_HM = 0x66,

      MOV_LA = 0x6F, MOV_LB = 0x68, MOV_LC = 0x69, MOV_LD = 0x6A, MOV_LE = 0x6B,
      MOV_LH = 0x6C, MOV_LL = 0x6D, MOV_LM = 0x6E,

      MOV_MA = 0x77, MOV_MB = 0x70, MOV_MC = 0x71, MOV_MD = 0x72, MOV_ME = 0x73,
      MOV_MH = 0x74, MOV_ML = 0x75,

      // Move immediate
      MVI_A = 0x3E, MVI_B = 0x06, MVI_C = 0x0E, MVI_D = 0x16, MVI_E = 0x1E,
      MVI_H = 0x26, MVI_L = 0x2E, MVI_M = 0x36,

      // load immediate (reg pair)
      LXI_B = 0x01, LXI_D = 0x11, LXI_H = 0x21, LXI_SP = 0x31,

      // load/store A direct ( from register pair )
      LDAX_B = 0x0A, LDAX_D = 0x1A, STAX_B = 0x02, STAX_D = 0x12,

      // load/store A direct ( from memory )
      LDA = 0x3A, STA = 0x32,

      // load/store HL direct
      LHLD = 0x2A, SHLD = 0x22,
    
      // exchange HL and DE
      XCHNG = 0xEB;

current readme doesn't provide any information about using the project or even building it.
of course this would not be the final product but would prove to be a strong foundation to make the project public and then work on it publicly with other possible contributors online.

• Add installation instructions to the README.md
• Add contribution guidelines to the README.md
• Complete the feedback section of the README.md
• Fill the license section of the README.md

tested program

#include "cpu.h"
#include <iostream>

int main() {
  emu::Memory mem;
  emu::CPU cpu;
  cpu.reset(mem);
  mem[0] = emu::CPU::LDA;
  mem[1] = 0x0;
  mem[2] = 0x0;
  mem[3] = emu::CPU::MOV_BA;
  int cycles = 4;
  cpu.execute(cycles, mem);
  std::cout << (int)cpu.getBRegister() << " < B\n";
  std::cout << (int)cpu.getARegister() << " < A\n";
  std::cout << (int)cpu.getProgramCounter () << " <pc\n";
  return 0;
}

The project requires a document file containing the contribution guidelines and instructions especially for new contributors those are looking forward to contribute to this repository.

currently the built test binary is not ignored by git and might add clutter to the source code if overlooked at later stage.

Sub-issues include

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The readme still doesn't include a proper API documentation and even if it did, having a small "how to use" section would help new users to directly use this library without much of a hassle.

without the cmake
it seems doesn't recognize the object file(cpu.o) both in windows and linux
ar: cpu.o: file format not recognized

with cmake
I only tested this at your CMakeLists at /src directory. main.cpp is not recognized when generating the project
removing that from CMakeLists it generates and builds successfully.
but it creates libcpu.a instead lib8080.a (judging by the last parameter of ar command)

both of the cases were tested on linux and windows with GCC and clang

8085's machine control instructions is a the instructions that can alter the flow of program. this controls the following groups of instructions

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move immediate instructions

containing the following opcodes

    MVI_A = 0x3E, MVI_B = 0x06, MVI_C = 0x0E, MVI_D = 0x16, MVI_E = 0x1E,
    MVI_H = 0x26, MVI_L = 0x2E, MVI_M = 0x36,

add an open source license to the project to make it accessible for other developers to use.

Add .clang-format file to the project with the formatting standards followed by the project ( the project currently uses LLVM coding standards ).

instructions to implement loading register pair with immediate addressing mode

LXI_B = 0x01, LXI_D = 0x11, LXI_H = 0x21, LXI_SP = 0x31,

load and store accumulator direct

 LDAX_B = 0x0A, LDAX_D = 0x1A, STAX_B = 0x02, STAX_D = 0x12,

These instructions control internal control stack.

instruction to exchange data between HL and DE register pair

// exchange HL and DE
XCHNG = 0xEB,

currently all the functions of class emu::cpu are publicly visible, ideally these functions should be private and only be used by emu::cpu::execute () to execute the proper instruction.

Doing so would make the program much less error prone and avoid any accidental function calls by users.

Though most of the dependencies are pretty straightforward and would most probably be present in almost any C++ developer's arsenal, README.md should not make any presumption and at least provide some basic hyperlinks to the download page or the product's official installation instructions.

these instructions perform I/O operation between accumulator and a specific port of the system.

These include instructions that alter the control flow by testing the conditional flags.

These instructions are meant to control the overall process of cpu

on a reset, the stack pointer should be reset to memory address FFFF

create a sample interface to see and display the changes a program does on registers/memory of the microprocessor.

set up build environment using Came for both building and testing using google test

instructions to load and store HL register pair using direct addressing mode

// load/store HL direct
LHLD = 0x2A, SHLD = 0x22,

the readme is just a giant text wall right now and needs a bit of tweeking to be more appealing to user's eyes.

These include a banner on top and some emojis in the text.

one test for testing each of the following instructions.

      MOV_AA = 0x7F,
      MOV_AB = 0x78, MOV_AC = 0x79, MOV_AD = 0x7A, MOV_AE = 0x7B, MOV_AH = 0x7C,
      MOV_AL = 0x7D, MOV_AM = 0x7E,

      MOV_BA = 0x47, MOV_BB = 0x40, MOV_BC = 0x41, MOV_BD = 0x42, MOV_BE = 0x43,
      MOV_BH = 0x44, MOV_BL = 0x45, MOV_BM = 0x46,

      MOV_CA = 0x4F, MOV_CB = 0x48, MOV_CC = 0x49, MOV_CD = 0x4A, MOV_CE = 0x4B,
      MOV_CH = 0x4C, MOV_CL = 0x4D, MOV_CM = 0x4E,

      MOV_DA = 0x57, MOV_DB = 0x50, MOV_DC = 0x51, MOV_DD = 0x52, MOV_DE = 0x53,
      MOV_DH = 0x54, MOV_DL = 0x55, MOV_DM = 0x56,

      MOV_EA = 0x5F, MOV_EB = 0x58, MOV_EC = 0x59, MOV_ED = 0x5A, MOV_EE = 0x5B,
      MOV_EH = 0x5C, MOV_EL = 0x5D, MOV_EM = 0x5E,

      MOV_HA = 0x67, MOV_HB = 0x60, MOV_HC = 0x61, MOV_HD = 0x62, MOV_HE = 0x63,
      MOV_HH = 0x64, MOV_HL = 0x65, MOV_HM = 0x66,

      MOV_LA = 0x6F, MOV_LB = 0x68, MOV_LC = 0x69, MOV_LD = 0x6A, MOV_LE = 0x6B,
      MOV_LH = 0x6C, MOV_LL = 0x6D, MOV_LM = 0x6E,

      MOV_MA = 0x77, MOV_MB = 0x70, MOV_MC = 0x71, MOV_MD = 0x72, MOV_ME = 0x73,
      MOV_MH = 0x74, MOV_ML = 0x75,

Implement different variations of restart instruction.

load and store accumulator direct

  LDA = 0x3A, STA = 0x32

create .gitignore file to keep the repository clean and free of messy build files.

The generated library has name liblib8085.a

It is also not in correct place as specified by README.md.