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+--- Thread: HP-20B test (/thread-139019.html)
HP-20B test - Scott Newell - 07-18-2008
Hold down PMT while turning on the unit. Options include "Tst Screen", "Tst Keyboard", "Checksum", "Tst Battery", "SW Version", "(c) Copyright 2008 HP Dev. C., L.P.", and "TSys Off".
TSys can be toggled on or off. Not sure what it does. Screen and keyboard test are pretty much what you'd expect. Mine shows a checksum of 213.213, battery of 3.500, and the software version is 6 24 2008 (tuesday) or 6.242.
Hit the input key while in battery test, and the display will switch to a live measurement. I ran it down to 2.1V before the readings became inaccurate. (It shut down at about 1.8V or so.)
Looks like the reset all key combo is hold down N and Amort while powering up.
Re: HP-20B test - cyrille de Brébisson - 07-19-2008
hello,
Quote:
Hold down PMT while turning on the unit. Options include "Tst Screen", "Tst Keyboard", "Checksum", "Tst Battery", "SW Version", "(c) Copyright 2008 HP Dev. C., L.P.", and "TSys Off".
actually, you just need to hold down ON and PMT simultaneously... just like on a 48....
TSys is to enable/disable the test system. when the test system is enable, the CPU NEVER goes into sleep mode and the calculator never shuts down, so I would discourage turning it on.
when the test system is on, you can send key codes to the calculator through the serial com and request screen dumps... this is of course used for the automated test system...
cyrille
Re: HP-20B test - Scott Newell - 07-19-2008
Quote:
TSys is to enable/disable the test system. when the test system is enable, the CPU NEVER goes into sleep mode and the calculator never shuts down, so I would discourage turning it on.
Nice to know, thanks! My JTAG setup really likes to have the CPU running when it connects (obviously), so I've been putting the calc in test mode, then starting my debugger. I'll try TSys too--that might be a bit easier, and my cute HP 6218A doesn't mind that the CPU never sleeps.
I was running some code (ARM, not thumb) from SRAM last night, playing around with the display. The LCD mapping is a bit confusing, so I haven't made much progress there.
FWIW, I'm really enjoying hacking on this one. Thanks a lot for leaving the JTAG pads in place!