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• Project Log #2

  Harold Moore • 2 hours ago • 0 comments

  Project Log #2 — Programming the Intel 8085 to Display KE6JMG

  Introduction

  With the Intel SDK-85 emulator successfully compiled and running under Ubuntu Linux, the next step was to develop an Intel 8085 machine-language program capable of producing a large ASCII-character banner.

  The objective was to display my amateur radio callsign:

  KE6JMG

  The program was developed using the SDK-85 monitor, with machine-code instructions entered directly into the emulator's memory.

  The finished demonstration produces an eight-line banner using printable ASCII characters and a compact method of encoding repeated spaces.

  This project log contains the recorded machine-code program, complete banner data, monitor commands, and terminal output.

  1. The Intel SDK-85 Emulator

  The emulator used for this project was originally developed by Kjetil, known as kobolt on GitHub.

  Original source repository:

  https://github.com/kobolt/sdk85emu

  The emulator is distributed under the MIT License.

  The software emulates the Intel 8085 processor and SDK-85 development environment, including the monitor and serial terminal facilities.

  My project uses this emulator to develop and execute an original ASCII banner demonstration.

  2. Program Design

  The banner generator separates the executable machine-code routine from the ASCII banner data.

  The executable program reads bytes sequentially from memory, interprets their values, and sends the resulting characters to the SDK-85 terminal.

  The program supports three important operations:

  1. Printing ordinary ASCII characters.
  2. Expanding encoded space characters into multiple spaces.
  3. Processing carriage returns to create multiple lines of output.

  A zero byte marks the end of the banner data.

  This approach reduces the amount of memory required to store large banners containing substantial blank space.

  3. Memory Organization

  The program uses the following memory locations:

  Purpose
  Executable Intel 8085 program
  Encoded KE6JMG banner data
  End-of-data terminator
  SDK-85 monitor output subroutine

  The machine-code routine begins at address 2010H.

  The banner data begins at 2800H and is processed sequentially.

  The program calls the SDK-85 monitor's output routines to generate the display.

  The byte at 2900H is set to zero, providing an end-of-data marker.

  4. Starting the Emulator

  Open the Ubuntu Linux terminal.

  Change to the SDK-85 emulator directory:

  cd ~/sdk85emu

  Start the emulator in serial terminal mode:

  ./sdk85emu -s

  The emulator displays:

  SDK-85   VER 2.1
  .

  The period is the SDK-85 monitor prompt.

  The following commands are entered into the SDK-85 monitor, not the Linux shell.

  5. Entering the Intel 8085 Machine-Code Program

  At the monitor prompt, enter:

  .I2010

  Then enter the following hexadecimal bytes:

  31 C2 20 21 00 28 7E 4F 23 FE 00 CA 90 05 07 DA
  34 20 0F FE 0D CA 2E 20 CD FA 07 C3 16 20 CD EB
  05 C3 16 20 0F E6 7F 57 0E 20 CD FA 07 15 C2 38
  20 C3 16 20 00

  Finish the memory-entry operation using:

  /*

  This is the machine-code sequence recorded during the successful development session.

  The program initializes its working registers, reads encoded banner data, and uses the SDK-85 monitor routines for terminal output.

  6. Entering the Complete KE6JMG Banner Data

  The banner data is stored separately from the executable instructions.

  At the monitor prompt, enter:

  .I2800

  Enter the following hexadecimal bytes exactly as shown:

  85 4B 20 20 4B 20 45 45 45 45 20 20 36 36 20 20
  20 4A 4A 4A 20 4D 20 20 20 4D 20 20 47 47 47 0D
  85 4B 20 4B 20 20 45 20 20 20 20 36 20 20 20 20
  20 20 20 4A 20 4D 4D 20 4D 4D 20 47 20 20 20 0D
  85 4B 4B 20 20 20 45 20 20 20 20 36 20 20 20 20
  20 20 20 4A 20 4D 20 4D 20 4D 20 47 20 20 20 0D
  85 4B 20 4B 20 20 45 45 45 20 20 36 36 36 20 20
  20 20 20 4A 20 4D 20 20 20 4D 20 47 20 47 47 0D
  85 4B 20 20 4B 20 45 20 20 20 20 36 20 20 36 20
  20 20 20 4A 20 4D 20 20 20 4D 20 47 20 20 47 0D
  85 4B 20 20 4B 20 45 20 20 20 20 36 20 20 36 20
  4A 20 20 4A 20 4D 20 20 20 4D 20 47 20 20...

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• Project Log #1

  Harold Moore • 2 hours ago • 0 comments

  Project Log #1 — Installing and Compiling the Intel SDK-85 Emulator Under WSL

  Introduction

  The first step in developing the KE6JMG ASCII Banner Display was establishing a working Intel SDK-85 emulator.

  The Intel SDK-85 was a development system designed around the Intel 8085 8-bit microprocessor. It provided a platform for experimenting with machine-language programming, memory operations, peripheral interfaces, and serial communications.

  For this project, I am using an open-source SDK-85 emulator running under Ubuntu Linux through Windows Subsystem for Linux (WSL) on a Windows 11 computer.

  This log explains how to obtain the original emulator, install the necessary development tools, compile the software, and run the SDK-85 monitor.

  1. Original Emulator and Author Credit

  The Intel SDK-85 emulator used in this project was originally developed by Kjetil, known as kobolt on GitHub.

  Original GitHub repository:

  https://github.com/kobolt/sdk85emu

  Original project documentation:

  https://kobolt.github.io/article-250.html

  The original emulator is distributed under the MIT License.

  Kjetil's software provides an emulated Intel 8085 processor, SDK-85 keyboard and display interface, serial terminal operation, memory support, and debugging facilities.

  The original emulator includes:

  • Intel 8085 CPU emulation
  • Intel 8279 keyboard/display interface
  • SDK-85 monitor ROM
  • Serial terminal operation
  • Debugging and breakpoint capabilities
  • Intel HEX ROM loading
  • Additional memory support

  Full credit for the original emulator belongs to Kjetil.

  My KE6JMG project builds upon this work by developing a custom Intel 8085 ASCII banner program, experimenting with character font tables, modifying the emulator startup environment, and investigating communication with an actual ASR-33 Teletype.

  The original copyright and license notices will be preserved in any redistributed modified emulator source code.

  2. Installing Windows Subsystem for Linux

  The development computer uses Windows 11.

  WSL allows Ubuntu Linux and its development tools to operate within Windows without requiring a separate Linux computer.

  Open Windows PowerShell as Administrator and enter:

  wsl --install -d Ubuntu

  Windows may request a restart.

  After restarting, open Ubuntu from the Windows Start menu.

  During the initial setup, Ubuntu will request a Linux username and password.

  To verify the installation, open PowerShell and enter:

  wsl --list --verbose

  The installed Ubuntu distribution should appear.

  3. Updating Ubuntu Linux

  Open the Ubuntu terminal.

  Update the package information:

  sudo apt update

  Upgrade installed packages:

  sudo apt upgrade -y

  These commands prepare the Linux environment for software development.

  4. Installing the Development Tools

  The SDK-85 emulator is written in C and uses terminal display libraries.

  Install the required development tools:

  sudo apt install -y build-essential make libncurses-dev git

  These packages provide:

  • GCC — GNU C compiler
  • Make — software build utility
  • ncurses — terminal display library
  • Git — source-code retrieval utility

  Verify that the compiler is available:

  gcc --version

  Verify Make:

  make --version

  Verify Git:

  git --version

  5. Downloading the Original SDK-85 Emulator

  The original source code is publicly available from Kjetil's GitHub repository.

  For a straightforward Linux installation, open the Ubuntu terminal and enter:

  cd ~

  Download the source:

  git clone https://github.com/kobolt/sdk85emu.git

  Enter the project directory:

  cd ~/sdk85emu

  Examine the downloaded files:

  ls -la

  The source directory contains several important files, including:

  Makefile
  main.c
  i8085.c
  i8085.h
  serial.c
  serial.h
  mem.c
  mem.h
  monitor.hex
  mcs85util.hex

  The monitor.hex file contains the SDK-85 monitor ROM image.

  The i8085.c source provides the Intel 8085 CPU emulation.

  The serial.c source handles serial communications.

  The Makefile contains the instructions required to compile the emulator.

  Note: During...

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