From 29f25bda7a03f4ac1c553930885f031b16d63eb4 Mon Sep 17 00:00:00 2001
From: n loewen <nick@nloewen.com>
Date: Sat, 26 Aug 2023 16:44:30 -0400
Subject: [PATCH] config / cpu - Add feature: Map the arrow keys to hex keypad,
 in addition to the larger Qwerty set

---
 cpu.js            |  7 +++----
 machine.config.js |  8 +++++++-
 readme.md         | 13 +++++++++++--
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/cpu.js b/cpu.js
index e5e5c2b..dbfa40c 100644
--- a/cpu.js
+++ b/cpu.js
@@ -307,10 +307,9 @@ function startCPU(code) {
   }
   process.stdin.on('keypress', (str, key) => { // TODO: is it possible to turn this off again?
     if (key.sequence === '\x03') process.exit();
-
-    str = str.toUpperCase();
-    if (str in KEY_MAP) {
-      CPU.memory[KEYPAD_ADDR] = KEY_MAP[str];
+    let name = key.name.toUpperCase();
+    if (name in KEY_MAP) {
+      CPU.memory[KEYPAD_ADDR] = KEY_MAP[name];
     }
   });
 }
diff --git a/machine.config.js b/machine.config.js
index e8e56e5..190ead1 100644
--- a/machine.config.js
+++ b/machine.config.js
@@ -16,10 +16,16 @@ module.exports = {
     'Q':'4',  'W':'5',  'E':'6',  'R':'D',
     'A':'7',  'S':'8',  'D':'9',  'F':'E',
     'Z':'A',  'X':'0',  'C':'B',  'V':'F',
+
+    // Include conventional arrow keys
+    'UP': '5',
+    'LEFT': '7',
+    'DOWN': '8',
+    'RIGHT': '9',
   },
 
   // max number of times to step the CPU,
   // to stop endless loops
   // 0 = infinite
-  "CYCLE_LIMIT": 256,
+  "DEFAULT_CYCLE_LIMIT": 2048,
 }
\ No newline at end of file
diff --git a/readme.md b/readme.md
index 62572e7..0dba40d 100644
--- a/readme.md
+++ b/readme.md
@@ -125,7 +125,7 @@ Put differently: it starts executing instructions at the address contained in `$
 
 The value of the latest keypress on a hex keypad is stored at `$1B`.
 
-The keypad uses the same layout as the COSMAC VIP (and CHIP-8). The CPU simulator maps those keys onto a Qwerty set.
+The keypad uses the same layout as the COSMAC VIP (and CHIP-8). The CPU simulator maps those keys onto a Qwerty set:
 
 ```
 1 2 3 C    1 2 3 4
@@ -133,7 +133,16 @@ The keypad uses the same layout as the COSMAC VIP (and CHIP-8). The CPU simulato
 7 8 9 E    A S D F
 A 0 B F    Z X C V
 
-  VIP     simulator
+hex pad    simulator
+```
+
+The arrow keys are also mapped onto the hex keypad:
+
+```
+   5           ↑
+ 7 8 9       ← ↓ →
+
+hex pad    simulator
 ```
 
 ## Assembly language