RELative file support in X16?

EMwhite · Post by **EMwhite** » Wed Jan 13, 2021 1:52 pm

Does/will X16 support REL files; assumed that the hardware will be happy to allow pushing 15 command channel commands to an IEC device, but does the emulator support it today and will the hardware support the emulation of code on an SD image?

I dusted off an old program I wrote in the 80s and have been enhancing it under VICE x64. Wondering if I should bother to continue; I read somewhere (here) that SEQ support was added specifically.

Thanks all

kktos · Post by **kktos** » Wed Jan 13, 2021 2:43 pm

Pardon my ignorance ? but what are REL files ?

TomXP411 · Post by **TomXP411** » Wed Jan 13, 2021 5:12 pm

2 hours ago, kktos said:

Pardon my ignorance ? but what are REL files ?

It's a mode designed for random access files. The file has two parts: a vector table and the actual record data. Essentially, the vector table is a list of indices into the table that allow you to point to various locations in the file and (I think) update the order of the records without physically re-writing the records (you would just change the index). I think the primary use cases was for databases, since a separate chain for indexes would let you re-order data without physically re-writing the data portion of the file.

kktos · Post by **kktos** » Wed Jan 13, 2021 7:16 pm

ok. got it now.

thanks ?

EMwhite · Post by **EMwhite** » Wed Jan 13, 2021 7:57 pm

5 hours ago, kktos said:

Pardon my ignorance ? but what are REL files ?

It's a random access construct (drive seeking) for fixed length 'records' with variable data held within with zero overhead required by the Commodore deivce.

With one command (via a 15 command channel), you can instantiate file of [as example] 192 characters per record; once created, you can open and close a file via simple open command without describing the structure; then via command channel, seek to any 'record' between 1 and 65535 with an offset in the record from 1st to 192nd character. Each record can have a varied structure (like a MongoDB document) and once open and positioned, you use typical "input #2,a$,b$" in order to read data.

Again, zero overhead to the computer, all done within the 1541 (as example) drive.

Anybody know?

BruceMcF · Post by **BruceMcF** » Thu Jan 14, 2021 6:27 am

The most recent word I saw was that they were not sure they would be implementing it, but that would not have been sometime before the start of the semester, so before mid September.

TomXP411 · Post by **TomXP411** » Thu Jan 14, 2021 8:00 am

I've never needed REL files, and they don't really exist on non-Commodore computers. Will we have the ability to seek within a file in SEQ files? I don't know CBM-DOS well enough to even know how to do that.

** edit: never mind. There is no seek command in SEQ files. So you either have to load the entire file into memory, then re-write it, or you need to use some other construct.

We definitely need the ability to seek within a file, but I'd be fine if we can simply issue a SEEK command with an open SEQ/PRG file (there is no distinction on the Commander.)

EMwhite · Post by **EMwhite** » Thu Jan 14, 2021 1:37 pm

VICE implemented it just fine... why not just reuse or is there a thorny licensing issue that does not seem to bother the VICE crowd but is an issue here? (made more challenging still because nobody knows what it is : )

Did the x64 developers actually start with nil and build up the entire legacy Commodore drive DOS but skip REL and USR portion of the code? Jim Butterfield (RIP) would be most disappointed.

My BBS User and Message manager can be rewritten but the catalog of TPUG PET Recipe and VHS cataloging programs have now died their 2nd death : (

TomXP411 · Post by **TomXP411** » Thu Jan 14, 2021 5:08 pm

3 hours ago, EMwhite said:

VICE implemented it just fine... why not just reuse or is there a thorny licensing issue that does not seem to bother the VICE crowd but is an issue here? (made more challenging still because nobody knows what it is : )

Did the x64 developers actually start with nil and build up the entire legacy Commodore drive DOS but skip REL and USR portion of the code? Jim Butterfield (RIP) would be most disappointed.

My BBS User and Message manager can be rewritten but the catalog of TPUG PET Recipe and VHS cataloging programs have now died their 2nd death : (

VICE is a virtual machine that runs the original Commodore software; the REL support on the virtual 1541 (and 1571, 1581, etc) is due to the ROMs that shipped with the drives that are being emulated. That's a completely different situation than what is happening here: the DOS code has to be written from ground zero, because there never has been (as far as I know) a CBM-DOS to FAT32 driver for 6502.

As to your legacy software... you always have the option to use a real 1541, a Pi1541, a 1541 Ultimate, a 1581, a Lt Kernel hard drive, or an SD2IEC, which does support REL files inside of disk images.

Lorin Millsap · Post by **Lorin Millsap** » Thu Jan 14, 2021 6:09 pm

I don’t believe we will support REL files on the integrated DOS.

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