Lerm Tape Utility C
Hi folks,
These Lerm tapes are doing my head in. Through the years I've aquired lots and lots of samples of these, but never been able to make a clean TZX of most.
I've got some examples here of Sides A & B from the tape:
http://dl.dropbox.com/u/15363623/tuc1a.zip
http://dl.dropbox.com/u/15363623/tuc1b.zip
The first 4 blocks (2 header + 2 data) and they are ROM blocks and can be stored with ID.10.
There's a 1 or 0 ms pause between the blocks, but the 4th seems to need 1161ms or so to allow the loader to kickin (I think)
The rest, 6 blocks in this case have a 1 or 0ms pause and use a turbo block (ID.11).
From most Lerm tapes I've looked at they have the following timings:
Pilot Pulse = 2165 : Pilot Length = 248
Sync 0 = 667 : Sync 1 = 735
Bit 0 = 856 : Bit 1 = 1712
I'm unsure whether the Bit values should follow the rule 1 = 0 * 2 or not ?
Sometimes the Sync values are changed by the convertors to 714:714, these are wrong
of course for standard timings.
Is there any clever bod out there who can find out what the timings should be.
I also have a problem with most of them where the final small block will not decode properly and result in a checksum error in the block. I don't know why this is ?
Finally if anyone want's to make up the tones that are between some of the blocks or at the end, that would be cool, but I don't think these are needed for loading, just to fool other copiers.
These Lerm tapes are doing my head in. Through the years I've aquired lots and lots of samples of these, but never been able to make a clean TZX of most.
I've got some examples here of Sides A & B from the tape:
http://dl.dropbox.com/u/15363623/tuc1a.zip
http://dl.dropbox.com/u/15363623/tuc1b.zip
The first 4 blocks (2 header + 2 data) and they are ROM blocks and can be stored with ID.10.
There's a 1 or 0 ms pause between the blocks, but the 4th seems to need 1161ms or so to allow the loader to kickin (I think)
The rest, 6 blocks in this case have a 1 or 0ms pause and use a turbo block (ID.11).
From most Lerm tapes I've looked at they have the following timings:
Pilot Pulse = 2165 : Pilot Length = 248
Sync 0 = 667 : Sync 1 = 735
Bit 0 = 856 : Bit 1 = 1712
I'm unsure whether the Bit values should follow the rule 1 = 0 * 2 or not ?
Sometimes the Sync values are changed by the convertors to 714:714, these are wrong
of course for standard timings.
Is there any clever bod out there who can find out what the timings should be.
I also have a problem with most of them where the final small block will not decode properly and result in a checksum error in the block. I don't know why this is ?
Finally if anyone want's to make up the tones that are between some of the blocks or at the end, that would be cool, but I don't think these are needed for loading, just to fool other copiers.
Post edited by Andrew Barker on
Comments
http://dl.dropbox.com/u/15363623/TUC.zip
Inside it is a WAV segment of the block, and also the tones often found on the LERM tapes.
There's also CSW, PZX and TXT output of these.
Finally, I've added a Side per side partially working TZXs. On Side 1 TUC works, but
CU5 doesn't. The 3rd program is just a TYPE to identify code blocks. This isn't present on Side B. Side B contains TUC and CU5 again, but TUC doesn't work and CU5 does.
I could of course use both sides to fix the full TZX, but the point is that I wonder why I have trouble converting these. There must be something at play. I don't know if it needs polarity, certain pause requirements or the SYNC or BIT values are wrong, or even if there's some pulses missing somewhere ?
Any help is welcome.
Cheers