HP Articles Forum

[Return to the Index ]
[ Previous | Next ]

Making sense of all the 41c Service ROM versions: 1A 1C 1D 2A 2B

Posted by Allen on 10 Mar 2008, 12:04 a.m.

Making sense of all the 41c Service ROM versions: 1A 1C 1D 2A 2B

Confused about the HP 41C Diagnostic/Service Roms? Chances are, you're not alone. There are five known types of HP 41C service ROM, and few concise guides exist regarding their use and nomenclature. Although they are all very rare, the two most common versions (SM1C and SM2A) are both called "Diagnostic" or "Service" module interchangeably- This can make using and trading them very confusing!

Here I discuss the key mapping and distinct advantages the of four different Service ROMS: (will be edited to add the 1D Version if time allows)

1. SM-1A prototype version of SM-1C?
2. SM-1C (a.k.a. ET-11966)
3. SM-1D To be resolved at a later date
4. SM-2A (a.k.a. 5061-7221)
5. SM-2B 82143A Printer and ROM tester (not shown)

		
		none     	HP 00041-60902	none     	none
		none     	ET-11966	5061-7221	ET-11968
Key		none     	SERVICE.MOD	SERVICE-CX.MOD	82143A SERVICE ROM
Code	Func.	SM1A	        SM1C	        SM2A	        SM2B
----------------------------------------------------------------------
01	ON	ON	        ON	        ON	        ON
02	USER	ALL TESTS	ALL TESTS	CX-MULT-TEST	PRINTER TEST
03	PRGM	(AUTO)	        (AUTO)	        CV-MULT-TEST	(AUTO)
04	ALPHA	(AUTO)	        (AUTO)	        (AUTO)	        (AUTO)
11	SIGMA	KEYBOARD	KEYBOARD	CX-KEYBOARD	N/U
12	1/X	KEY-CODE	KEY-CODE	CX-KEY-CODE	N/U
13	SQRT	DISPLAY     	DISPLAY     	CX-DISPLAY	N/U
14	LOG	DATA STORAGE	DATA STORAGE	CX-DATA STORAGE	N/U
15	LN	ROM TEST	ROM TEST	CX-ROM TEST	N/U
21	x<>Y	KEYBOARD	KEYBOARD	CV-KEYBOARD	N/U
22	R DN	KEY-CODE	KEY-CODE	CV-KEY-CODE	N/U
23	SIN	DISPLAY	        DISPLAY     	CV-DISPLAY	N/U
24	COS	DATA STORAGE	DATA STORAGE	CV-DATA STORAGE	N/U
25	TAN	ROM TEST	ROM TEST	CV-ROM TEST	N/U
31	SHIFT	STANDBY	        STANDBY     	STANDBY 	N/U
32	XEQ	SLEEP	        SLEEP   	SLEEP   	N/U
33	STO	CHARACTER	CHARACTER	CHARACTER	N/U
34	RCL	MEM-MOD 	MEM-MOD 	MEM-MOD 	N/U
35	SST	APP-MOD1	APP-MOD1	4K APP MOD	N/U
41	ENTER	APPL-MOD ID	APPL-MOD ID	APPL-MOD ID	N/U
42	CHS	CPU      	CPU     	CPU     	N/U
43	EEX	I/O PORT	I/O PORT	X-MEM MOD	N/U
44	<--	APP MOD 2	APP MOD 2	8KAP ROM	N/U
51	-	ROM ID  	ROM ID  	ROM ID  	N/U
52	7	N/U     	N/U     	TIME CHIP (CX)	N/U
53	8	N/U     	N/U     	GEN ROM TST	GEN ROM TEST
54	9	SERV MOD TST	SERV MOD TST	SERV MOD TST	SERV MOD TST
61	+	N/U     	CR QA     	N/U     	N/U
62	4	N/U     	CR MOTOR	TIME MOD (CV)	N/U
63	5	N/U     	CR BUFFER	X FUNCT (CV)	N/U
64	6	N/U     	CR READ TST	12K APP MOD	N/U
71	*	N/U     	CR WRITE TST	N/U     	N/U
72	1	N/U     	N/U     	FREQ (W/TIME)	N/U
73	2	N/U     	N/U          	N/U             STATUS REG
74	3	N/U     	N/U     	16K APP MOD	EOL TEST
81	/	DEBOUNCE	DEBOUNCE	DEBOUNCE	N/U
82	0	N/U     	N/U	        N/U     	N/U
83	.	N/U     	N/U     	N/U     	N/U
84	R/S	STOP TEST	STOP TEST	STOP TEST	STOP TEST

N/U =NOT USED	    SM 4K page must be loaded on PG 4 of HP41 memory

SM1A Advantages

1. More Rare than SM1C modules
2. Can test MEM (82106A) and 4k/8k APP modules

SM1C Advantages

1. Adds Card reader tests to the SM1A
2. Can test MEM (82106A) and 4k/8k APP modules

SM2A Advantages

1. Adds 12k, 16K, X-FUNCTION, X-MEMORY ROM tests
2. Adds TIME chip, TIME MOD, and FREQ test
3. SM2A can test QUAD mem rather than 1MEM
4. Disadvantage: NO card reader test available in SM2A

SM2B Advantages

1. Can test 82143A Printer functions as well as General ROM test

A note regarding the emulation of Service ROMs:

1. GENERAL APP
2. QUAD MEM
3. TIME MOD
4. X MEM

References/Further Information

1. SM1A- No further information available
2. SM1C- See HP-41C Service Manual available here
3. SM2A- See HP-41C Service Manual available here
4. SM2B- See HP 82143A Service Manual available elsewhere online

Edited: 10 Mar 2008, 12:33 a.m.

[ Return to the Message Index ]

Go back to the main exhibit hall