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LIF questions - Johnboy - 03-21-2023 09:25 AM
Hi All,
Just wondering a couple of things about LIF files, firstly; what the maximum size of a LIF volume and secondly; can a LIF volume store a mixture of HP-41 and HP-71 files ?
Thanks
John
RE: LIF questions - J-F Garnier - 03-21-2023 11:16 AM
It depends on the context.
For LIF volumes in general, volumes can be very large, since the pointers to the 256-byte records are stored on 32 bits. So the maximum size may be something like 1TB, however there may be other limitations.
For LIF volumes in the field of our calculators and HP-IL drives (real or emulated), the size is much less, since the Filbert protocol used by the HP-41C/71B/75C uses pointers coded on 16 bits, so the maximum size is 16MB "only".
Then, you should know that the HP-41C can only manage 128kB volume with the standard functions of the HP-IL module. It can, however, manage up to 1MB with the Extended-IL module (do not confuse it with the X-IO module).
For the second question, yes you can store HP-41C and HP-71B files on the same volume, however this is not recommended, because if you later purge or update files, bad things can happen.
So for archival purpose, yes it is possible (many archive volumes have both types of files), but for working purpose, it is not recommended and it is better to keep 41C files on a dedicated volume.
J-F
RE: LIF questions - Johnboy - 03-21-2023 10:09 PM
Thanks J-F, that's really good information.
My questions relate to building Tobie's Arduino/HP-IL project, and wondering how big the SD card(s) should be.
Cheers,
John
RE: LIF questions - brouhaha - 03-22-2023 03:53 AM
(03-21-2023 11:16 AM)J-F Garnier Wrote: Then, you should know that the HP-41C can only manage 128kB volume with the standard functions of the HP-IL module
Isn't that 41C 128KiB limit just for initializing the medium? I recall using something like 630KiB with 9114 floppy drives without any issues other than initialization. The 82183A Extended I/O module allows initializing a medium larger than 128KiB, using a program in the "HP 9114A Using Your Disk Drive" manual (User's Library program #41-09114).
There's probably some other limit to what the 41C HP-IL firmware can handle. IIRC, a few megabytes works, but since there's only a flat directory, it's going to get quite unweildy.
RE: LIF questions - brouhaha - 03-22-2023 05:14 AM
(03-21-2023 10:09 PM)Johnboy Wrote: My questions relate to building Tobie's Arduino/HP-IL project, and wondering how big the SD card(s) should be.
The maximum size of a LIF volume is 16MiB. Unless you find an ancient SD card, it's unlikely that an HP-41C can use the full card.
RE: LIF questions - Johnboy - 03-22-2023 07:19 AM
Thanks Brouhaha,
16MB sounds reasonable, so I can use the smallest SD card I have, being 512MB :-)
Also, which Extended I/O module command is used to create a new volume ?
I used the 82160 IL module NEWM command to initialise a tape (128K).
Thanks
John
RE: LIF questions - J-F Garnier - 03-22-2023 07:58 AM
(03-22-2023 03:53 AM)brouhaha Wrote:(03-21-2023 11:16 AM)J-F Garnier Wrote: Then, you should know that the HP-41C can only manage 128kB volume with the standard functions of the HP-IL module
Isn't that 41C 128KiB limit just for initializing the medium? I recall using something like 630KiB with 9114 floppy drives without any issues other than initialization. The 82183A Extended I/O module allows initializing a medium larger than 128KiB, using a program in the "HP 9114A Using Your Disk Drive" manual (User's Library program #41-09114).
There's probably some other limit to what the 41C HP-IL firmware can handle. IIRC, a few megabytes works, but since there's only a flat directory, it's going to get quite unweildy.
It's not just about initializing, otherwise it would be easy to initialize a disk with the 71B then use the full capacity with the 41.
The problem is that the 41C doesn't use the disk descriptor in sector 0, so *always* assumes the volume is 128kB (the size of the 82161 cassettes) when creating new entries in the catalog.
However, if a file is already existing beyond the 128kB, the 41C can access it (read and re-write). This was the purpose of the utility provided by HP in the 9114 manual: create a directory entry beyond 128KB.
In the same way, the Extended-IL module provides new functions for creating files, but regular HP-IL functions are still used for reading.
My experience showed that volumes up to 1MB can be used with the Extended-IL. IIRC, this module also doesn't use the disk descriptor, but just tries to access sectors up to 1MB, to find out the capacity of the disc.
Edit: quote from the Extended-IL manual:
"All of the write functions in the HP-IL module have been modified to allow their use on mass storage devices of up to 1 megabyte."
See also the addendum with the SNEWM bug.
J-F