Home

• Installing and running the emulator

Boards

• CPU board
• Memory board
• Serial board
• Storage board
• Video board
• Debugger board

BIOS

• Monitor
• System calls

Hardware Specification

CPU

• Upon initialization, the CPU will start running the BIOS code at address 0x0.

Memory

• The memory map is as follows:

• The BIOS is contained between 0x0000 and 0x1fff.
• The shared memory (between 0x2000 and 0x3fff) is accessible from any bank. This can be used for storing variables when an application spans more than one memory bank. Positions between 0x2000 and 0x23ff are reserved for the BIOS.
• The upper memory (between 0x4000 and 0xffff) can be bankswitched in 8 different memory banks.
• If the register RAMONLY is active, then the whole 64kB of memory can be accessed as a single RAM. This is meant primarily to be used by CP/M, but can be used for other pourposes as well. If this mode is activated, backswitching will not work.

I/O

The I/O ports are as follows:

Port	Direction	Description
0x00	Output	Configure memory manager (bits 0~2: memory bank, bit 3: RAMONLY)
0x01	Output	Write to the config register in 68B50
0x01	Input	Read from the state register in 68B50
0x02	Output	Transfer byte to SDCard
0x02	Input	Read last byte sent by the SDCard
0x05	Output	Write to the serial line (TX)
0x05	Input	Read from the serial line (RX)

Bus

This is the pinout of the bus:

CPU, memory and debugger use all ports of the bus. Other peripherals (such as serial and storage) use only ports A, B, C and G.

Advanced

• Communication protocol between the PC debugger client and server, and the debugger board
• Uploading the debugger firmware
• BIOS memory locations