IO Devices

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The Input/Output Devices

Input/Output devices are external components that communicate through the processor's IO Bus and pads.

Currently, the simulation includes 8 IO devices and 3 memory devices. The following table provides a summary of the address ranges used for each device:

Address Range	Device	Notes
[0x00000000–0x00fffffc[	RAM	Stores instructions and data
0x00fffffc	Random Number Generator	Generates a random byte on each read
0x00fffffd	Switches	Provides one byte of binary input
0x00fffffe	Joystick	Provides 2D input with 4 bits per axis
0x00ffffff	Keyboard	Provides ASCII input
[0x01000000–0x01100000[	Screen	Each address corresponds to a pixel on the screen
[0x01100000–0x01100002[	Terminal	First byte receives ASCII characters; second byte clears the terminal
[0x01100002–0x80000000[	Not Allocated	--
[0x80000000–0x81000000[	Trap Handler	ROM containing a special program to handle interrupts and exceptions
[0x81000000–0x81000010[	Real-Time Device	Provides time and timer interrupt signals
0x81000010	Software Interrupt Reg	Writable bit that triggers a software interrupt signal
[0x81000011–0xff000000[	Not Allocated	--
[0xff000000–0xffffffff[	OS RAM	Secondary RAM used alongside the Trap Handler ROM

The simulation allows users to add custom IO devices by removing existing ones or using unallocated address ranges.