The Museum of HP Calculators

HP Forum Archive 08

[ Return to Index | Top of Index ]

Rhode Systems II ROM
Message #1 Posted by Philip (Houston, TX) on 2 Apr 2002, 11:54 a.m.

I have acquired a ROM without documentation that I'm curious about. It is labeled "RHODESYSTEMS II". It has a part number of 82500A-A18, ID31. It appears to have an autorun configured because when it is placed in the HP41 and turned on, the system displays "WORKING..." and then beeps with USER mode on. The functions appear in CAT2 with the little "t" preceeding the label name implying to me they can be copied to RAM. A COPY yields a PRIVATE message. The functions are: F-S S-F H-S D-S S-D FT-S S-FT S-M SOLVE Y/N FX HIT ZZ RESET FILM NDF EBU DF FT FR FH CLK MET BEAT MS SEC- BEAT1 FSTRT VSTRT SET SUB ADD COMP LISTH ADDH CHGH CHGW READH RECOVER

There seems to be some connection with the TIME module. When Shift-On is pressed, the calc displays WORKING... again and then displays time. The S-H, S-M and their inverse appear to convert Seconds to hours, seconds to minute and so on.

Anyone have any ideas about this ROM?

Re: Rhode Systems II ROM (Just wondering...)
Message #2 Posted by Vieira, Luiz C. (Brazil) on 2 Apr 2002, 7:28 p.m.,
in response to message #1 by Philip (Houston, TX)


very peculiar. As you mentioned, the little "t" means that you are dealing with programs (this is the same "t" you see in any ALPHA label, except for the 2-byte A-J, a-e). What I am curious about is that the programs are made PRIVATE (un-PRIVATing them is another story) and the calc begins an autostart routine. In time: are you using an HP41C/CV or CX? Just to know if SHIFT-ON is active or not.

If you are not using a time module OR an HP41CX, this module has an internal clock (is it possible to simulate time counting in the HP41 with, say, synhtetic program?). Wow! I want to know more about it...

Now it makes two curious in the place. Someone? Ahn?

Re: Rhode Systems II ROM (Just wondering...)
Message #3 Posted by Philip (Houston, TX) on 3 Apr 2002, 11:20 a.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)

In a CV without the TIME module: Shift-ON turns the calc off as expected. In a CV with the TIME module: Shift-ON starts the Clock and responds the same as a CX.

In a module with PRIVATE programs, can the programs actually be copied to memory but maintain their private status? If so, can someone point me to a way to UN-PRIVATE programs in memory.

Another curious thing, at startup, something is copied to memory that is protected. A CAT1 displays nothing but pressing PRGM displays PRIVATE which implies to me a PRIVATE program was automatically copied into memory. With a SIZE 100 on a CX there are 219 registers, after the startup with the ROM, there are 206 registers. Thanks

Re: Rhode Systems II ROM (this is getting even better...)
Message #4 Posted by Vieira, Luiz C. (Brazil) on 3 Apr 2002, 11:48 a.m.,
in response to message #3 by Philip (Houston, TX)

Mam, this is amazing! I suspected that the SHIFT-ON was related to the Time Functions, alright.

About unprivating: try this link, that you will see how. I believe that some internal 41's trick is probably active; I'd not be frustrated if this PRIVATE stuff maintain itself private even after the unprivate procedure.

I'm still a lot curious about this fella. I believe some knowledge of the 41's synth prgm and internals will be of help. I wish I know more about it...

Success. And please, keep us informed.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall