If you’re working on an old computer, sometimes you just don’t have a second unit to use for testing. That’s why it’s sometimes handy to have a tester for certain components. This tester is used for the 4116 RAM modules found in many old systems including the Commodore PET, Mac and Atari systems. It’s different than some other modules because it needs +12, +5 and -5 volts, while many others only need +5. Below is the schematic for building the tester.
As you can see, this schematic uses two ICL7660 ic’s to create the +12 and -5 volt lines. From there it is simply a matter of making all of the connections from the Arduino to your ZIF or normal socket. The LCD and DIP switch are both optional.
The following is the Arduino code. If you decide want to use an LCD you’ll have to install the LiquidCrystal package to your Arduino IDE or use other one if you’d like. It all depends how you want to do it. I’ve used a PCF8574 module and the LiquidCrystal_8574 library for my project. There are, however, other ways to go about it.
You can also just download the Arduino file here https://www.kosciuskomedia/4116_Tester.ino
You can watch the video series by going here The Tech I Missed – 4116 RAM tester project
Also, feel free to email any questions you may have or if you need some help. mailto:admin@kosciuskomedia.com
and now the code:
include <Wire.h>
include <LiquidCrystal_PCF8574>
/*
- above is only needed if you want to use an LCD
*/
#define DI 7 // Arduino Nano D7 > 4116 pin 2
#define DO 15 // Arduino Nano A1 > 4116 pin 14
#define CAS 14 // Arduino Nano A0 > 4116 pin 15
#define RAS 5 // Arduino Nano D5 > 4116 pin 4
#define WE 6 // Arduino Nano D6 > 4116 pin 3
#define Add_0 4 // Arduino Nano D4 > 4116 pin 5
#define Add_1 2 // Arduino Nano D2 > 4116 pin 7
#define Add_2 3 // Arduino Nano D3 > 4116 pin 6
#define Add_3 17 // Arduino Nano A3 > 4116 pin 12
#define Add_4 9 // Arduino Nano D10 > 4116 pin 9
#define Add_5 8 // Arduino Nano D11 > 4116 pin 8
#define Add_6 16 // Arduino Nano A2 > 4116 pin 13
#define RED_LED 10 // Anode to pin 10 (D10)
#define GR_LED 11 // Anode to pin 11 (D11)
#define BUS_SIZE 7
//follow is only needed if using LCD. From this point, anything with LCD is only
//needed if using an LCD
LiquidCrystal_PCF8574 lcd(0x27);
volatile int bus_size;
const unsigned int a_bus[BUS_SIZE] = {
Add_0, Add_1, Add_2, Add_3, Add_4, Add_5, Add_6
};
void setup() {
int i;
Serial.begin(9600);
//Wire only needed for LCD
Wire.begin();
Wire.beginTransmission(0x27);
lcd.begin(16, 2); // initialize the lcd
lcd.setBacklight(200);
lcd.setCursor(0, 0);
lcd.print(“-4116 RAM Test-“);
lcd.setCursor(0, 1);
Serial.println();
Serial.print(“c= [4116 RAM Tester] c= \n \n”);
bus_size = BUS_SIZE;
for (i = 0; i < BUS_SIZE; i++)
pinMode(a_bus[i], OUTPUT);
pinMode(CAS, OUTPUT);
pinMode(RAS, OUTPUT);
pinMode(WE, OUTPUT);
pinMode(DI, OUTPUT);
pinMode(RED_LED, OUTPUT);
pinMode(GR_LED, OUTPUT);
pinMode(DO, INPUT);
digitalWrite(WE, HIGH);
digitalWrite(RAS, HIGH);
digitalWrite(CAS, HIGH);
digitalWrite(RED_LED, HIGH);
digitalWrite(GR_LED, HIGH);
Serial.flush();
digitalWrite(RED_LED, LOW);
digitalWrite(GR_LED, LOW);
noInterrupts();
for (i = 0; i < (1 << BUS_SIZE); i++) {
digitalWrite(RAS, LOW);
digitalWrite(RAS, HIGH);
}
digitalWrite(RED_LED, HIGH);
digitalWrite(GR_LED, HIGH);
}
void setBus(unsigned int a) {
int i;
for (i = 0; i < BUS_SIZE; i++) {
digitalWrite(a_bus[i], a & 1);
a /= 2;
}
}
void writeAddress(unsigned int r, unsigned int c, int v) {
/* address row */
setBus(r);
digitalWrite(RAS, LOW);
/* rw */
digitalWrite(WE, LOW);
/* value */
digitalWrite(DI, (v & 1)? HIGH : LOW);
/* address column */
setBus(c);
digitalWrite(CAS, LOW);
digitalWrite(WE, HIGH);
digitalWrite(CAS, HIGH);
digitalWrite(RAS, HIGH);
}
int readAddress(unsigned int r, unsigned int c) {
int ret = 0;
/* address row */
setBus(r);
digitalWrite(RAS, LOW);
/* address column */
setBus(c);
digitalWrite(CAS, LOW);
/* get current value */
ret = digitalRead(DO);
digitalWrite(CAS, HIGH);
digitalWrite(RAS, HIGH);
return ret;
}
void error(int r, int c)
{
unsigned long a = ((unsigned long)c << bus_size) + r;
digitalWrite(RED_LED, HIGH);
digitalWrite(GR_LED, LOW);
interrupts();
Serial.print(” Test Failed at address: $”);
Serial.println(a, HEX);
Serial.flush();
lcd.setCursor(0,0);
lcd.print(” “);
lcd.setCursor(0,0);
lcd.print(“Test Failed!!”);
lcd.setCursor(0,1);
lcd.print(” “);
lcd.setCursor(0,1);
lcd.print(“at address: $” + String(a,HEX));
turn_off_leds();
while (1);
}
void ok(void)
{
digitalWrite(RED_LED, LOW);
digitalWrite(GR_LED, HIGH);
interrupts();
lcd.setCursor(0,0);
lcd.print(” “);
lcd.setCursor(2,0);
lcd.print(“RAM is good!”);
lcd.setCursor(0,1);
lcd.print(” “);
lcd.setCursor(0,1);
lcd.print(“-wait a second-“);
Serial.println(“\n this 4116 RAM module is good “);
Serial.flush();
turn_off_leds();
while (1);
}
void wait_for_reset(void)
{
while(1);
}
void turn_off_leds(void)
{
delay(6000);
digitalWrite(RED_LED, LOW);
digitalWrite(GR_LED, LOW);
delay(500);
blink();
//digitalWrite(RED_LED, LOW);
//digitalWrite(GR_LED, LOW);while(1);
}
void blink(void)
{
digitalWrite(RED_LED, LOW);
digitalWrite(GR_LED, LOW);
delay(200);
digitalWrite(RED_LED, HIGH);
digitalWrite(GR_LED, HIGH);
delay(200);
digitalWrite(RED_LED, LOW);
digitalWrite(GR_LED, LOW);
delay(200);
digitalWrite(RED_LED, HIGH);
digitalWrite(GR_LED, HIGH);
delay(200);
digitalWrite(RED_LED, LOW);
digitalWrite(GR_LED, LOW);
delay(200);
digitalWrite(RED_LED, HIGH);
digitalWrite(GR_LED, HIGH);
delay(200);
Serial.print(“\n ready for another 4116 module”);
lcd.setCursor(0,0);
lcd.print(” “);
lcd.setCursor(0,0);
lcd.print(“-4116 RAM Test-“);
lcd.setCursor(0,1);
lcd.print(” “);
lcd.setCursor(0,1);
lcd.print(“ready 4 another”);
}
void green(int v) {
digitalWrite(RED_LED, v);
}
void fill(int v) {
int r, c, g = 0;
v &= 1;
for (c = 0; c < (1 << bus_size); c++) {
green(g? HIGH : LOW);
for (r = 0; r < (1 << bus_size); r++) {
writeAddress(r, c, v);
if (v != readAddress(r, c))
error(r, c);
}
g ^= 1;
}
}
void fillx(int v) {
int r, c, g = 0;
v &= 1;
for (c = 0; c < (1 << bus_size); c++) {
green(g? HIGH : LOW);
for (r = 0; r < (1 << bus_size); r++) {
writeAddress(r, c, v);
if (v != readAddress(r, c))
error(r, c);
v ^= 1;
}
g ^= 1;
}
}
void loop()
{
interrupts(); lcd.setCursor(0,1); lcd.print(” “); lcd.setCursor(0, 1);lcd.print(“running pass 1”); Serial.print(“writing/reading…\n”); Serial.flush(); noInterrupts(); fillx(0);
interrupts(); lcd.setCursor(0,1); lcd.print(” “);lcd.setCursor(0, 1);lcd.print(“running pass 2”); Serial.print(“writing/reading…\n”); Serial.flush(); noInterrupts(); fillx(1);
interrupts(); lcd.setCursor(0, 1); lcd.print(” “);lcd.setCursor(0, 1);lcd.print(“running pass 3”); Serial.print(“writing/reading…\n”); Serial.flush(); noInterrupts(); fill(0);
interrupts(); lcd.setCursor(0, 1); lcd.print(” “);lcd.setCursor(0, 1);lcd.print(“running pass 4”); Serial.print(“writing/reading…\n”); Serial.flush(); noInterrupts(); fill(1);
ok();
}
