Z8C-Homebrew-Computer

Using the build tools

The Z8C uses the zmac macro assembler (http://48k.ca/zmac.html)

To easily develop for my Z80 homebrew system, I designed a simple assempler development environment. This packs the following tasks into one script:

• zmac assembly
• object file creation (for xmodem upload)
• monitor file creation (creates monitor commands for ascii upload)
• symbol table include file generation
• eeprom programming for the minipro

Prequisites

• zmac - self-compiled version included in ./Utility.
• minipro (https://gitlab.com/DavidGriffith/minipro)
• binutils (apt-get install binutils-multiarch, pacman -S aarch64-linux-gnu-binutils )

Building a project

./build.sh <dir> <asm filename>

• dir: Path to the location of the asm file
• asm filename: name of the assembly file without suffix

    # e.g.:
    cd ./Utility
    ./build.sh ../OperatingSystem/monitor_v2  
    ./build.sh ../OperatingSystem/software  

Building a project with a properties file

./build.sh <dir>

• dir: Path to the location of the asm file

The directory must contain a file called properties.env This file can contain project-specific options.

Example:

export OPT_GEN_SYMBOLTABLE=1
export OPT_GEN_MONFILE=0
export OPT_GEN_OBJFILE=1
export OPT_WRITEROM=1
export FILENAME=main

Options

• OPT_GEN_SYMBOLTABLE if set to 1: Generates the symbols.s file
• OPT_GEN_MONFILE if set to 1: Generates the monitor file
• OPT_GEN_OBJFILE if set to 1: Generates the object file
• OPT_WRITEROM if set to 1: Starts eeprom programmer
• FILENAME same as the <asm filename> paramter of the build script
• ROOT_DIR overrides the project root path. required if git is not used
• EEPROM_PART sets EEPROM part for minipro. Default: AT28C256

System design

The Z80 Hombrew computer is modular computer system, designed arround a custom backplane.

Available modules

Z8C CPU/COM Board

• Z80 ZPU @ 4MHz (6MHz planned)
• 64 KiB SRAM
• 32 KiB EEPROM (R/W switchable)
• Z80 CTC with external 1.8432MHz Clock switchable per channel
• Z80 SIO (Up to 115200 BAUD possible @ X16 SIO prescaler)
• 1 FTDI Connector
• 1 RS232 DSUB-9 Port
• 8 front-facing DIP switches (currently used for baud-rate setup)
• Power-On-Reset Circuit

Memory Layout
       Default ($00 = 0x00)  Mode 1 ($00 = 0x02)  Mode 2 ($00 = 0x01)             
$0000 +--------------------+--------------------+--------------------+
      | EEPROM Lower 16KiB | EEPROM Upper 16KiB | SRAM               |
$4000 +--------------------+--------------------+                    |
      | SRAM               | SRAM               |                    | 
      |                    |                    |                    |
      |                    |                    |                    |
$FFFF +--------------------+--------------------+--------------------+

Note: In default mode and mode 1, the MEMAQ pin (pin a5 on backplane) 
      can be used to inject an external memory device in the $0000-$3FFF 
      window.

IO Addresses:
$00 Memory register
$01 DIP Switches
$04 CTC (First address)
$08 SIO (First address)

Z8C MIO Board

• Z80 PIO (Used for GPIO and non Z80 compliant interrupt handling)
• VT82C42 PS/2 controller
• AM5911A (only usable with CPU-Clock under 3 MHz)
• PFC8584 I2C Controller
• DS1307 RTC
• 8-Bit GPIO Port

//TODO: Add more Info

Z8C Disk Interface Board

• Intel 82C55 based IDE Interface
• FDC9266 Floppy Disk Controller

//TODO: Add more Info