File question

[senior_falcon]

I believe with variable, the biggest record size allowed is 254. 

 

My bad. Yes, that is correct. Long XB files are saved as IV254.

[RXB]

Yea minimum size of 3 sectors can be saved in RXB in 254 format vs XB format.

Example: SAVE DSK1.TEST,IV254

(This can be used in Console only in RXB.)

 

Maximum size of XB program format is Line number table plus program size minus 64 bytes for stack, plus 256 for line buffer.

This would use all of the VDP memory available.

Any program in memory larger must be in upper 24K so will be saved in IV254 format.

No matter if you have a 32K or not does not matter as when 32K exists all XB programs are moved to upper 24K automatically.

Still all XB programs are using VDP to load or save.

 

[apersson850]

If you want to use all the space in the sectors you can go for fixed 128 file. Two such records fill one sector precisely. You can't do one 256 byte record, since record sizes are one byte long only.

[+Lee Stewart]

4 hours ago, apersson850 said:

If you want to use all the space in the sectors you can go for fixed 128 file. Two such records fill one sector precisely. You can't do one 256 byte record, since record sizes are one byte long only.

 

Precisely how TurboForth and fbForth do it for blocks files.

 

...lee

[RXB]

2 hours ago, apersson850 said:

If you want to use all the space in the sectors you can go for fixed 128 file. Two such records fill one sector precisely. You can't do one 256 byte record, since record sizes are one byte long only.

I think PROGRAM FORMAT is best as it uses every byte by 256 at a time each sector as there is no byte count per sector.

 

[GDMike]

That's what I'm doing in SNP, using the "program" type records, is there a term other than, "program"? Program is so general..

[Tursi]

2 hours ago, RXB said:

I think PROGRAM FORMAT is best as it uses every byte by 256 at a time each sector as there is no byte count per sector.

It's actually the same with Fixed128, that's also why it's used to read PC files. The only difference is whether you get access to discrete parts or only the whole file (using the default I/O calls anyway).

[apersson850]

Yes, and with the memory image format (how's that for something different than PROGRAM?), the standard DSR limits the file's length to what can fit in the VDP buffer.

The p-system uses a fixed 128 dummy file to mark the whole disk as used. But it doesn't use that file itself, it does a direct sector read/write access instead.