Re: NoV-64: The Incredible Shrinking HEPAX RAM Message #18 Posted by Diego Díaz on 25 May 2012, 4:31 p.m., in response to message #1 by Les Wright
Hi Les,
I cannot reproduce the behavior you've depicted, but I think I can help in bringing the HEPAX RAM of your File System back to its default size.
Just to point it out, the amount of HEPAX RAM available for File System has nothing to do with and should not be altered by the configuration of the extra ROM pages in the NoV modules.
Conversely, once the amount of RAM in the File System has been altered (for whichever the cause), re-programming the NoV module with its default (only HEPAX emulation) configuration won't turn the "missing" RAM back.
The following is a simple procedure to, first, find out if your RAM is available and, second, recover it to the File System in case you need it.
1- To check if RAM chip is properly accessible from the NoV module please execute HEPAX 002. You'll see a list of every page with a descriptive label of its contents. "HEPAX RAM" should fill pages #8, #9, #A & #B. Please note that the amount of HEPAX RAM used by HEPAX File System (the amount showed up by HEPROOM command), does not necessarily match the total amount of available RAM. See HEPAX manual for details on the File System configuration, as well as File System Chain integrity details.
2- You can repeat the abobe checking for the remaining three chips by changing control word at address h'4100 to h'001, h'002 & h'003 respectively by means of HEXEDIT command.
In order to get one 16K chip of HEPAX RAM back to the File System, and get the 2,160 registers count, HEPAX provides an easier method than the CLR_RAM configuration.
3- Assign CLRAM command to a key of your convenience, place "OK" into ALPHA register, enter 11 to X register and execute CLRAM, then 10 & CLRAM, 9 & CLRAM and 8 & CLRAM. Power cycle your HP-41 once finished. Now HEPROOM will show your 2,610 registers as expected.
4- Repeat the process for chips 001, 002 and 003 if required.
Just to clarify, CLR_RAMn utilities do not draw more battery than any other operation. The need of a fresh set of batteries does not come from the current drain requirements but from the voltage expected to run the continuous writing/reading process. This is beacuse this particular utility runs while the HP-41 is OFF therefore, the internal power supply is not working and the only available voltage is the one in the batteries less a diode drop.
Despite of this, this utility is currently of little to no real usage since the latest NoV modules version all include the Crash Recovery Feature which allows total RAM erasing by following the steps 3 & 4. See the NoV-64 module user's manual for details.
Hope this helps.
All the best from Caribbean Sea.
Diego.
Edited: Typos.
Edited: 25 May 2012, 4:32 p.m.
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