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HP 42S: Difference between revisions
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<nowiki>*</nowiki>note: the top row of keys are customarily labeled A-F from left to right. | <nowiki>*</nowiki>note: the top row of keys are customarily labeled A-F from left to right. | ||
HP 42s has two resets: Master reset which puts the calculator back to "factory condition", clearing all memory with On+A+F and Machine reset with On+C which interrupts any program | HP 42s has two resets: Master reset which puts the calculator back to "factory condition", clearing all memory with On+A+F and Machine reset with On+C which interrupts any program and sets the calculator into a set state ready to receive user input again, but does not cause any memory loss. | ||
As with the HP 27S and HP 17B, the self test is triggered with On+D. | As with the HP 27S and HP 17B, the self test is triggered with On+D. | ||
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Due to having its ROM dumped and emulators developed (and many exploration prior) the memory layout of the HP-42s is generally well know: | Due to having its ROM dumped and emulators developed (and many exploration prior) the memory layout of the HP-42s is generally well know: | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+Memory Layout of HP-42s | ||
(left inclusive right exclusive) | |||
!Address Start (hex) | !Address Start (hex) | ||
!Address End (hex) | !Address End (hex) | ||
| Line 50: | Line 51: | ||
|- | |- | ||
|00000 | |00000 | ||
| | |20000 | ||
|ROM | |ROM | ||
| | |Executing from 00000 is the only way to exit the debugger without using a reset. | ||
Executing from 023F1 (default entry point for debugger) displays the software revision and a one byte warm-start log. (often erroneously reported along with revision, e.g. A7, C5.....) | |||
|- | |- | ||
|40000 | |40000 | ||
|4020C | |4020C | ||
|Display | |Display | ||
|Column 0, 66, 1, 67 ........ 64, 130, 65 with 4 nybbles per column for 16 pixels, 131 columns in total. | |Column 0, 66, 1, 67 ........ 64, 130, 65 with 4 nybbles per column for 16 pixels per column, 131 columns in total. | ||
|- | |- | ||
| | |40210 | ||
| | |4024D | ||
| | |Annunciators | ||
| | |Each word contains five nybbles that is either 00000 (off) or FFFFF (on). | ||
40210-40215 is a word that lights up all announciator. | |||
from 40218 to 4024D each word controls multirow, shift, printing, busy, battery low, G and RAD (together forming GRAD) annunciators respectively. | |||
|} | |} | ||