HP 50g posts.

know-how/hardware/_posts/2017-03-18-hp-50g.md

@@ -0,0 +1,21 @@
+---
+title: HP 50g
+layout: default
+language: en
+created: 2017-03-18 16:14:51 +0100
+updated: 2017-03-18 16:14:51 +0100
+toc: false
+tags:
+  - know-how
+  - hardware
+  - hp
+  - 50g
+  - calculator
+---
+![HP 50g]({{ site.url }}/assets/hp-50g.jpg)
+
+<ul>
+{% for page in site.categories.hp-50g %}
+  <li><a href="{{ page.url }}">{{ page.title }}</a></li>
+{% endfor %}
+</ul>

know-how/hardware/hp-50g/_posts/2017-03-18-missed-keypresses.md

@@ -0,0 +1,57 @@
+---
+title: HP 50g and missed keypresses
+layout: default
+language: en
+created: 2017-03-18 22:29:30 +0100
+updated: 2017-03-18 22:29:30 +0100
+toc: false
+tags:
+  - know-how
+  - hardware
+  - hp
+  - 50g
+  - calculator
+---
+The default key debouncing wait time in the HP 50g is very long so that it misses lots of
+keypresses when typing fast. E.g. when typing `500` the calculator only registers `50`. This
+behaviour is controlled by the `KEYTIME` setting.
+
+The `KEYTIME` setting specifies the number of processor ticks, any further keypresses are ignored
+after a key was pressed. The default value is **1138** which resembles about 140 ms.
+
+Setting this to e.g. **500** (~61 ms) makes entering numbers much more reliable. Some users even
+disabled it by setting it to **0** and had no problems at all.
+
+
+Changing the value
+==================
+
+To set the `KEYTIME` setting to **500**, press the following keys (in RPN mode):
+
+1. <kbd>5</kbd><kbd>0</kbd><kbd>0</kbd>
+1. <kbd>ENTER</kbd>
+1. <kbd>ALPHA</kbd><kbd>ALPHA</kbd>
+1. <kbd>K</kbd><kbd>E</kbd><kbd>Y</kbd><kbd>T</kbd><kbd>I</kbd><kbd>M</kbd><kbd>E</kbd>
+1. <kbd>STO ▶</kbd>
+
+But this only works for the current session. After a reboot of the device, the value will be back
+to the default value of **1138** again.
+
+
+Changing the value on bootup
+============================
+
+To have this value changed on every bootup of the calculator, we have to save the instructions
+to a special variable called `STARTUP`. To do this, press the following keys (in RPN mode):
+
+1. <kbd>↱</kbd><kbd>+</kbd> (this will insert `<< >>` and place the cursor in the middle)
+1. <kbd>5</kbd><kbd>0</kbd><kbd>0</kbd>
+1. <kbd>↱</kbd><kbd>0</kbd> (this will insert a `→`)
+1. <kbd>ALPHA</kbd><kbd>ALPHA</kbd>
+1. <kbd>K</kbd><kbd>E</kbd><kbd>Y</kbd><kbd>T</kbd><kbd>I</kbd><kbd>M</kbd><kbd>E</kbd>
+1. <kbd>ENTER</kbd>
+1. <kbd>S</kbd><kbd>T</kbd><kbd>A</kbd><kbd>R</kbd><kbd>T</kbd><kbd>U</kbd><kbd>P</kbd>
+1. <kbd>STO ▶</kbd>
+
+This stores the instruction into the special variable `STARTUP` which gets evaluated on every
+bootup.