From d677fc5de0568924b39eecae11a24f40566860b9 Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sun, 9 May 2021 13:53:41 -0700
Subject: Keyboard input.

---
 hdl/core.sv   | 27 +++++++++++++++++++++++++--
 mem/hello.pal | 13 ++++++++++---
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/hdl/core.sv b/hdl/core.sv
index 02ff231..7edf523 100644
--- a/hdl/core.sv
+++ b/hdl/core.sv
@@ -67,6 +67,9 @@ bit [8:0] operand;
 bit [DATA_BITS-1:0] acc;
 bit link;
 
+bit kbd_valid;
+bit [DATA_BITS-1:0] kbd_data;
+
 bit i;
 bit z;
 bit [6:0] wip;
@@ -93,9 +96,14 @@ always_ff @(posedge clk) begin
         pc = 'o200;
         acc = 0;
         link = 0;
+        kbd_valid = 0;
         state = state.first;
     end else begin
         if (`lag(tx_ready)) tx_valid = 0;
+        if (rx_ready && `lag(rx_valid)) begin
+            kbd_valid = 1;
+            kbd_data = {4'b0, 1'b1, `lag(rx_data[6:0])};
+        end
 
         case (state)
             FETCH: begin
@@ -115,7 +123,7 @@ always_ff @(posedge clk) begin
                 if (`lag(mem_read_valid)) begin
                     state = FETCH;
                     {opcode, operand} = `lag(mem_read_data);
-                    $display("%d decode %x: %b %b", $time, pc-1, opcode, operand);
+                    //$display("%d decode %x: %b %b", $time, pc-1, opcode, operand);
                     {i, z, wip} = operand;
                     if (z)
                         address = {page, wip};
@@ -191,6 +199,19 @@ always_ff @(posedge clk) begin
                         end
                         'b110: begin
                             case (operand[8:3])
+                                'b000011: begin
+                                    case (operand[2:0])
+                                        'b001: if (kbd_valid) pc++;
+                                        'b110: begin
+                                            acc = kbd_data;
+                                            kbd_valid = 0;
+                                        end
+                                        default: begin
+                                            $display("unsupported keyboard op %b", operand[2:0]);
+                                            $finish;
+                                        end
+                                    endcase
+                                end
                                 'b000100: begin
                                     case (operand[2:0])
                                         'b001: if (!tx_valid) pc++;
@@ -199,7 +220,7 @@ always_ff @(posedge clk) begin
                                             tx_data = {1'b0, acc[6:0]};
                                         end
                                         default: begin
-                                            $display("unsupported device op %b", operand[2:0]);
+                                            $display("unsupported tty op %b", operand[2:0]);
                                             $finish;
                                         end
                                     endcase
@@ -320,6 +341,8 @@ always_ff @(posedge clk) begin
                 $finish;
             end
         endcase
+
+        rx_ready = !kbd_valid;
     end
 end
 
diff --git a/mem/hello.pal b/mem/hello.pal
index 437ccf9..989eff8 100644
--- a/mem/hello.pal
+++ b/mem/hello.pal
@@ -4,14 +4,19 @@ START,	CLA CLL
 	DCA 10
 LOOP,	TAD I 10
 	SNA
-	JMP EXIT
+	JMP ECHO
 	TLS
 	TSF
 	JMP .-1
 	CLA
 	JMP LOOP
-EXIT,	HLT
-	JMP START
+ECHO,	KSF
+	JMP .-1
+	KRB
+	TLS
+	TSF
+	JMP .-1
+	JMP ECHO
 HELLO,	.
 	"H
 	"e
@@ -26,5 +31,7 @@ HELLO,	.
 	"l
 	"d
 	"!
+	15
+	12
 	0
 $
-- 
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