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--- 20b:software-flash_4_banger [2008/07/30 22:20]
newell created
+++ 20b:software-flash_4_banger [2008/07/30 22:23] (current)
newell Uploaded binary file.
@@ Line 1: / Line 1: @@
+{{:20b:flash_4_banger.tgz|}}===== RPN hex 4 banger =====
+==== Description ====
+A flash resident(!) sample program, this time a dirt-simple 4 function hex calculator (32 bit ints only).
+==== Usage ====
+Use SAM-BA or any other comfortable flash programming tool to install the .bin file.  It's less than
+kB.  Of course, you will lose any existing firmware in your HP-20B, so be sure you backup the stock
+HP firmware before erasing it.
+Expect RAM to be corrupted if you decide to reload the stock HP firmware.
+Install this firmware at your own risk.
+==== Download link ====
+ {{20B:flash_4_banger.tgz}}
+==== Readme.txt ====
+Another basic sample program for the HP20B.  This time it's a four
+banger 32 bit hex calculator.  I think it's RPN, but it may not be
+exactly correct...
+Use the top row (N -> Amort) for the A -> F hex digits.
+Active keys include "(" (roll down), "Input" (enter), "+/-" (chs), "CE"
+(ce), "<-" (backspace/ce), and the four functions.  Oh, the shift key
+now works.  The only shifted function is off, which is shift+on.
+The "Input" LCD annunciator will be active when an unterminated value is
+present in the X register.  (The RPN annuciator comes on at boot to show
+that the program is running.)
+The scancode of the last keypress is shown in the exponent area of the
+LCD.
+Runs from flash, Thumb mode, trashes memory, and requires some sort of
+flash programming tool to install.
+There's no keypad debouncing--the code simply waits for the key to be
+released.  I'm sure that spinlock is very coin cell friendly.  I
+measured less than 100nA (very hard to measure, my Tek TX3 current meter is too noisy
+for a clean measurement) in off mode, and about 2mA while running.  There
+is no power management at all--no sleep mode, no halts, no interrupts, and no
+auto off timer.
+I'll add source as soon as I've had a chance to double check and
+add some comments.
+Disclaimer: Yes, the code is ugly.  Fix it at your own risk.  Consider
+it nothing more than a toy to demonstrate that we know a little about
+the hardware.
+Happy HP Hacking!

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