RomOnlyComputer now has a GUI

core/src/periph/at28c256/program.rs

@@ -2,9 +2,29 @@ use crate::constants::constants_system::SIZE_32KB;
 use crate::periph::at28c256::At28C256;
 
 impl At28C256 {
-    pub fn program(&mut self, new_program: &[u8; SIZE_32KB]) {
+    pub fn program(&mut self, new_program: Box<[u8]>) {
         // panic!("FAIL.  Cant program the chip.");
         // println!("PROGRAMMING {:?}", new_program);
-        self.data = Box::new(*new_program);
+        self.data = new_program;
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::periph::rom_chip::RomChip;
+    use super::*;
+
+    #[test]
+    fn smoke() { assert!(true) }
+
+    #[test]
+    fn programming_chip_changes_contents() {
+        let mut chip = At28C256::new(0x0000, 0x3fff, vec![]);
+
+        assert_eq!(0x00, chip.read(&0x0000));
+
+        let new_data: Vec<u8> = vec![0xff, 0xff, 0xff, 0xff];
+        chip.program(new_data.into());
+        assert_eq!(0xff, chip.read(&0x0000));
     }
 }

core/src/periph/at28c256/rom_chip.rs

@@ -3,10 +3,30 @@ use crate::periph::at28c256::At28C256;
 use crate::periph::rom_chip::RomChip;
 
 impl RomChip for At28C256 {
+    /// read
+    ///
+    /// Reads a byte from memory.
+    /// Returns a 0x00 if there is no data at that location but is still in ROM address range
     fn read(&self, offset: &u16) -> u8 {
-        self.data[*offset as usize]
+        println!("STARTING READ FROM At28C256 ${:04x} | ${:04x} | ${:04x}", self.offset, offset, self.max_offset);
+        if offset < &self.offset || offset > &self.max_offset {
+            println!("Unable to read from ${offset:04x} as it it out of range.");
+            return 0x00;
+        } else {
+            println!("OK READ FROM GOOD AREA total len = {}", self.data.len());
+        }
+
+        if *offset >= self.data.len() as u16 {
+            0x00
+        } else {
+            self.data[*offset as usize]
+        }
+
     }
 
+    /// program
+    ///
+    /// Writes new data to the memory chip
     fn program(new_data: &[u8; SIZE_32KB]) -> Box<At28C256> {
         println!("Writing new chip.");
         let mut working = At28C256::default();

core/src/periph/hm62256/tick.rs

@@ -8,7 +8,7 @@ impl Hm62256 {
 
     pub fn tick(&mut self, address_bus: u16, data_bus: u8, read_mode: bool, cs: bool) -> (u16, u8) {
         println!("HM62256RAM TICK START -> 0x{address_bus:04x} 0x{data_bus:02x} {read_mode} {cs}");
-        if !(address_bus.gt( &self.offset) && address_bus.le(&self.max_address())) {
+        if !(address_bus >= self.offset && address_bus < self.max_address()) {
             return (address_bus, data_bus);
         }
 
@@ -26,6 +26,7 @@ impl Hm62256 {
             return (address_bus, data_bus);
         }
 
+
         // ok.  lets see what we are dealing with
         self.data_bus = if read_mode {
             self.data[addr as usize]