All bugs are described in detail in the book „Extend your HP-41“ by W. A. C. Mier-Jędrzejowicz.
|#1||Early machines did not save X into L when Σ+ and Σ- were done.|
Example: 41 Σ+ LastX, if you do not see 41 bug is present.
|#2||Early machines allowed RCL IND nn and STO IND nn when nn was outside the memory range.|
Example: Master Clear, SIZE 000, 999, ENTER, π, STO IND Y, CLST, 999, RCL IND X. If π is displayed, bug is present and the question is where is it being stored if the machine doesn’t have any data registers?
|#3||Early machines allowed SF,CF,FS?C, and FC?C IND nn with nn any number (but not a stack register) 0 to 55.|
Example: 49, STO OO, SF IND 00. If you see the BAT indicator bug is present.
|#4||Early models compute the SIN of small angles incorrectly.|
Example: 1 EEX CHS 99 SIN. If the result is 0.174532925 bug is present.
|#5||CLP would only clear 1089 program lines.|
|#6||-67A/-97A programs that contain combinations of number entry, EEX, and CHS do not translate correctly.|
Example: EEX CHS 7 CHS 5 translates to E-7-5 instead of 1E-7 -5.
|#7||The second nybble of the seventh byte of Alpha is copied along with the first six bytes during an ASTO.|
|#8||Early machines do not decompile programs if they are turned off during PRGM mode.|
|#9||Executing CAT 1 while in PRGM mode, then interrupting it with R/S causes step labelling oddities.|
|#10||If flag 25 is set and MEAN or SDEV causes an overflow, some flags can be altered.|
|#11||If a program at the end of CAT 1 is replaced or deleted, a return to that program will return into the new program or off-program memory.|
|#12||On early models, the function LN(1+X) gives wrong answers for values of X between -.9990234374 and -1.00.|
|#13||On early models, the operation (.1)^-43 gives an answer of 9.999999999E42 instead of 1E43.|
HP-41 ROM Versions
first -41CV version
|HFF||84??-present||current -41CV version|
|NFL||2329-present||current -41CX version|