SIMM

SIMM RAM is a library for the Arduino MEGA 2560 that can be used to control 30 pin SIMM RAM modules.

First, Why ?!

I made this library mostly for fun, but I also had a use for it. I needed to show changing images on a display, but it would take 2 or 3 seconds to update because I was loading them from an SD card. But with the ram, I can just load the images to RAM on startup and read them very quickly when I need them !

Pros and cons:

Pros:

• VERY fast !
• A lot of storage compared to the internal ram of the arduino (can be up to 16Mb)
• No other components needed except the RAM module itself

Cons:

• Takes a bit of CPU power aprox. 16 times per second to refresh the RAM
• Uses a lot of wires (27 wires to be exact)

How to use the library

You will need:

• An Arduino MEGA 2560
• A 30 pin SIMM RAM module
• Wires to connect it all up

The schematic:

• DQ0 - DQ7 -> PORTL
• A0 - A7 -> PORTA
• A8 -> Pin 37
• A9 -> Pin 36
• A10 -> Pin 35
• A11 -> Pin 34
• CAS -> Pin 32
• WE -> Pin 31
• RAS -> Pin 30

Functions:

void begin();                                                                   // Initialize RAM
void stop();                                                                    // Stop RAM
byte read(uint16_t row, uint16_t column);                                       // Read a byte from RAM
void write(uint16_t row, uint16_t column, byte data);                           // Write a byte to RAM
void readBlock(uint16_t row, uint16_t column, uint16_t length, byte array[]);   // Read a block of bytes from RAM
void writeBlock(uint16_t row, uint16_t column, byte array[]);                   // Write a block of bytes to RAM