Adding clocking mechanism for serial data transmission

devices/pc8080/machine/README.md

@@ -13,4 +13,4 @@ The following 8080-based machines are currently available:
 * [Space Invaders (1978)](invaders/) (with [Debugger](invaders/debugger/))
 * [DEC VT100 Terminal](vt100/) (with [Debugger](vt100/debugger/))
 
-And check out the [Dual VT100 Terminals](vt100/dual/) for a demo of two PCjs machines communicating over a *virtual* serial connection. 
+Check out the [Dual VT100 Terminals](vt100/dual/) for a demo of two PCjs machines communicating over a *virtual* serial connection. 

devices/pc8080/machine/vt100/README.md

@@ -14,7 +14,8 @@ This is a PCjs work-in-progress emulation of another 8080-based machine: the VT1
 
 Unlike other VT100 emulators, it is not simply an emulation of VT100 protocols.  It is a simulation of the original VT100
 machine, running the [VT100 Firmware](/devices/pc8080/rom/vt100/) inside the [PC8080](/modules/pc8080/) CPU emulator.
-A [Debugger Configuration](/devices/pc8080/machine/vt100/debugger/) is also available.
+
+A [Debugger Configuration](debugger/) is also available, along with a [Dual VT100 Terminals](dual/) demo. 
 
 Admittedly, terminals aren't that useful in isolation, since they're designed to be connected to other (host) machines.
 But once this PCjs VT100 Terminal simulation is fully operational, you can expect to see it used in conjunction with a variety

devices/pc8080/machine/vt100/dual/README.md

@@ -20,6 +20,8 @@ This is a test of two [VT100 Terminals](../) whose serial ports are *virtually*
 terminal should appear on the screen of the second, and vice versa.  Click or tap on the screen of the desired terminal before
 you begin typing.
 
+A [Dual Debugger Configuration](debugger/) is also available.
+
 If either terminal becomes LOCKED, press the SET-UP key (mapped to your F9 function key) twice to unlock it. 
 
 {% include machine.html id="vt100a" %}

devices/pc8080/machine/vt100/dual/debugger/README.md

@@ -0,0 +1,29 @@
+---
+layout: page
+title: Dual VT100 Terminals with Debuggers
+permalink: /devices/pc8080/machine/vt100/dual/debugger/
+machines:
+  - id: vt100a
+    type: pc8080
+    debugger: true
+    autoStart: true
+    messages: serial|mem|port
+    config: /devices/pc8080/machine/vt100/debugger/machine.xml
+    connection: serialPort=vt100b.serialPort
+  - id: vt100b
+    type: pc8080
+    debugger: true
+    autoStart: true
+    messages: serial|mem|port
+    config: /devices/pc8080/machine/vt100/debugger/machine.xml
+    connection: serialPort=vt100a.serialPort
+---
+
+Dual VT100 Terminals with Debuggers
+-----------------------------------
+
+[Dual VT100 Terminals](../) with Debuggers attached.
+
+{% include machine.html id="vt100a" %}
+
+{% include machine.html id="vt100b" %}

modules/pc8080/lib/serialport.js

@@ -361,9 +361,13 @@ SerialPort.prototype.initBus = function(cmp, bus, cpu, dbg)
     this.dbg = dbg;
 
     var serial = this;
-    this.timerReceiveData = this.cpu.addTimer(function() {
-        serial.printMessage("timerReceiveData()");
-        serial.receiveData()
+    this.timerReceiveNext = this.cpu.addTimer(function() {
+        serial.printMessage("timerReceiveNext()");
+        serial.receiveData();
+    });
+    this.timerTransmitNext = this.cpu.addTimer(function() {
+        serial.printMessage("timerTransmitNext()");
+        serial.transmitData();
     });
 
     this.chipset = /** @type {ChipSet} */ (cmp.getMachineComponent("ChipSet"));
@@ -570,6 +574,11 @@ SerialPort.prototype.receiveByte = function(b)
 /**
  * receiveData()
  *
+ * Helper for clocking received data at the expected RECV_RATE.
+ *
+ * Currently, this is only use for test data that we "cram" down the terminal's throat, ensuring that we don't
+ * cram it too rapidly.
+ *
  * @this {SerialPort}
  */
 SerialPort.prototype.receiveData = function()
@@ -579,7 +588,7 @@ SerialPort.prototype.receiveData = function()
             this.sDataReceived = this.sDataReceived.substr(1);
         }
         if (this.sDataReceived && this.cpu) {
-            this.cpu.setTimer(this.timerReceiveData, this.getBaudTimeout(SerialPort.UART8251.BAUDRATES.RECV_RATE));
+            this.cpu.setTimer(this.timerReceiveNext, this.getBaudTimeout(SerialPort.UART8251.BAUDRATES.RECV_RATE));
         }
     }
 };
@@ -602,10 +611,7 @@ SerialPort.prototype.transmitByte = function(b)
     }
 
     if (this.controlIOBuffer) {
-        if (b == 0x0D) {
-            this.iLogicalCol = 0;
-        }
-        else if (b == 0x08) {
+        if (b == 0x08) {
             this.controlIOBuffer.value = this.controlIOBuffer.value.slice(0, -1);
             /*
              * TODO: Back up the correct number of columns if the character erased was a tab.
@@ -613,13 +619,17 @@ SerialPort.prototype.transmitByte = function(b)
             if (this.iLogicalCol > 0) this.iLogicalCol--;
         }
         else {
-            var s = String.fromCharCode(b);
-            var nChars = (b >= 0x20? 1 : 0);
+            var s = str.toASCIICode(b);
+            var nChars = s.length;
             if (b == 0x09) {
                 var tabSize = this.tabSize || 8;
                 nChars = tabSize - (this.iLogicalCol % tabSize);
                 if (this.tabSize) s = str.pad("", nChars);
             }
+            else if (b == 0x0D) {
+                this.iLogicalCol = nChars = 0;
+                s = "\n";
+            }
             if (this.charBOL && !this.iLogicalCol && nChars) s = String.fromCharCode(this.charBOL) + s;
             this.controlIOBuffer.value += s;
             this.controlIOBuffer.scrollTop = this.controlIOBuffer.scrollHeight;
@@ -641,6 +651,21 @@ SerialPort.prototype.transmitByte = function(b)
     return fTransmitted;
 };
 
+/**
+ * transmitData()
+ *
+ * Helper for clocking transmitted data at the expected XMIT_RATE.
+ *
+ * When timerTransmitNext fires, we have honored the programmed XMIT_RATE period, so we can
+ * set XMIT_READY (and XMIT_EMPTY), which signals the firmware that another byte can be transmitted.
+ *
+ * @this {SerialPort}
+ */
+SerialPort.prototype.transmitData = function()
+{
+    this.bStatus |= (SerialPort.UART8251.STATUS.XMIT_READY | SerialPort.UART8251.STATUS.XMIT_EMPTY);
+};
+
 /**
  * isTransmitterReady()
  *
@@ -698,8 +723,20 @@ SerialPort.prototype.outData = function(port, bOut, addrFrom)
     this.printMessageIO(port, bOut, addrFrom, "DATA");
     this.bDataOut = bOut;
     this.bStatus &= ~(SerialPort.UART8251.STATUS.XMIT_READY | SerialPort.UART8251.STATUS.XMIT_EMPTY);
-    if (this.transmitByte(bOut)) {
-        this.bStatus |= (SerialPort.UART8251.STATUS.XMIT_READY | SerialPort.UART8251.STATUS.XMIT_EMPTY);
+    /*
+     * If we're transmitting to a virtual device that has no measurable delay, this code may clear XMIT_READY
+     * too quickly.
+     *
+     *      if (this.transmitByte(bOut)) {
+     *          this.bStatus |= (SerialPort.UART8251.STATUS.XMIT_READY | SerialPort.UART8251.STATUS.XMIT_EMPTY);
+     *      }
+     *
+     * A better solution is to arm a timer based on the XMIT_RATE baud rate, and clear the above bits when that
+     * timer fires.  Consequently, we no longer care what transmitByte() reports.
+     */
+    this.transmitByte(bOut);
+    if (this.cpu) {
+        this.cpu.setTimer(this.timerTransmitNext, this.getBaudTimeout(SerialPort.UART8251.BAUDRATES.XMIT_RATE));
     }
 };
 

modules/pc8080/lib/video.js

@@ -1115,7 +1115,7 @@ Video.prototype.updateVT100 = function(fForced)
             /*
              * Cell cache logic is complicated by the fact that a line may be single-width one frame and double-width
              * the next.  So we store the visible line length at the start of each row in the cache, which must match if
-             * the cache is considered valid for the current line.
+             * the cache can be considered valid for the current line.
              */
             var fLineCacheValid = this.fCellCacheValid && (this.aCellCache[iCell] == nColsVisible);
             this.aCellCache[iCell++] = nColsVisible;
@@ -1153,6 +1153,9 @@ Video.prototype.updateVT100 = function(fForced)
          * cache entry, to guarantee that it's redrawn on the next update.
          */
         this.assert(iCellUpdated >= 0);
+        if (DEBUG && (this.aCellCache[iCellUpdated] & 0x7f) == 0x48) {
+            console.log("spurious character?");
+        }
         this.aCellCache[iCellUpdated] = -1;
         cUpdated = 0;
     }

modules/shared/lib/strlib.js

@@ -381,7 +381,7 @@ str.replaceArray = function(a, s)
  * @param {string} s is a string
  * @param {number} cch is desired length
  * @param {boolean} [fPadLeft] (default is padding on the right)
- * @returns {string} the original string (s) with spaces padding it to the specified length
+ * @return {string} the original string (s) with spaces padding it to the specified length
  */
 str.pad = function(s, cch, fPadLeft)
 {
@@ -393,7 +393,7 @@ str.pad = function(s, cch, fPadLeft)
  * trim(s)
  *
  * @param {string} s
- * @returns {string}
+ * @return {string}
  */
 str.trim = function(s)
 {
@@ -403,4 +403,56 @@ str.trim = function(s)
     return s.replace(/^\s+|\s+$/g, "");
 };
 
+str.aASCIICodes = {
+    0x00:   "NUL",
+    0x01:   "SOH",      // Start of Heading
+    0x02:   "STX",      // Start of Text
+    0x03:   "ETX",      // End of Text
+    0x04:   "EOT",      // End of Transmission
+    0x05:   "ENQ",      // Enquiry
+    0x06:   "ACK",      // Acknowledge
+    0x07:   "BEL",      // Bell
+    0x08:   "BS",       // Backspace
+    0x09:   "TAB",      // Horizontal Tab
+    0x0A:   "LF",       // Line Feed (New Line)
+    0x0B:   "VT",       // Vertical Tab
+    0x0C:   "FF",       // Form Feed (New Page)
+    0x0D:   "CR",       // Carriage Return
+    0x0E:   "SO",       // Shift Out
+    0x0F:   "SI",       // Shift In
+    0x10:   "DLE",      // Data Link Escape
+    0x11:   "DC1",      // Device Control 1
+    0x12:   "DC2",      // Device Control 2
+    0x13:   "DC3",      // Device Control 3
+    0x14:   "DC4",      // Device Control 4
+    0x15:   "NAK",      // Negative Acknowledge
+    0x16:   "SYN",      // Synchronous Idle
+    0x17:   "ETB",      // End of Transmission Block
+    0x18:   "CAN",      // Cancel
+    0x19:   "EM",       // End of Medium
+    0x1A:   "SUB",      // Substitute
+    0x1B:   "ESC",      // Escape
+    0x1C:   "FS",       // File Separator
+    0x1D:   "GS",       // Group Separator
+    0x1E:   "RS",       // Record Separator
+    0x1F:   "US"        // Unit Separator
+};
+
+/**
+ * toASCIICode(b)
+ *
+ * @param {number} b
+ * @return {string}
+ */
+str.toASCIICode = function(b)
+{
+    var s = str.aASCIICodes[b];
+    if (s) {
+        s = '<' + s + '>';
+    } else {
+        s = String.fromCharCode(b);
+    }
+    return s;
+};
+
 if (NODE) module.exports = str;