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mankeli
Registered: Oct 2010
Posts: 146 |
Spindle and Sparkle demos not launching
Can someone explain why demos using Sparkle or Spindle loaders can't be run from 1541U by selecting the launch file and using "mount & run"?
You got to use "Run Disk" for the whole image. 99.9999% of the C64 demos can be launched with mount & run, and somehow this only seems affect those aforementioned loaders. |
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Krill
Registered: Apr 2002
Posts: 2981 |
Note that reset/powercycle just before running can cause other issues.
Here's a decades-old code snippet from the olden days before 1541U et al.:stepperfix: ; here, the drive was apparently reset immediately before running the loader -
; step down a track: this works normally if the stepping bits are congruent with the stepper motor.
; however, it may happen that the bits are misaligned (opposite to the actual stepper position, bit 1
; reversed), this alone does not move the head but stepping makes it go into the direction opposite to
; the one desired when moving. the stepping down two halftracks will actually step up and step down one
; halftrack each and thus will end up on the same track as before, but align the stepper bits to the motor.
ldy #2
sty CURRTRACK41
dey
jsr trkseek41
stepperok:This kind of thing is relevant only when going full bare-metal, though, DOS "I" routine should work fine. =)
Edit: Thinking about it, not so sure any more about the last bit. |
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chatGPZ
Registered: Dec 2001
Posts: 11390 |
anything that reads from the disk (using DOS/jobcode) should realign the stepper with the usual +/-0.5 tracks dance, no? |
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Krill
Registered: Apr 2002
Posts: 2981 |
Quoting chatGPZanything that reads from the disk (using DOS/jobcode) should realign the stepper with the usual +/-0.5 tracks dance, no? Only after errors. The problem of incongruent stepper bits may thus appear only after stepping (so after DOS-init and switching to bare-metal routines). |
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chatGPZ
Registered: Dec 2001
Posts: 11390 |
But we were talking about "I" command, no? When there is no error, its all fine? :) |
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tlr
Registered: Sep 2003
Posts: 1791 |
Quote: But we were talking about "I" command, no? When there is no error, its all fine? :)
it is, but a subsequent custom track seek needs to consider that the stepper bits can be incorrect and do "the dance" it self. |
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chatGPZ
Registered: Dec 2001
Posts: 11390 |
But how would they be, after succesfull "I"? Wouldn't the DOS set them at least once? |
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tlr
Registered: Sep 2003
Posts: 1791 |
Not sure if the are touched at all if not trying to move the head. A seek to track 18 if you are already there probably won't move anything. |
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Sparta
Registered: Feb 2017
Posts: 49 |
Please correct me if I’m mistaken but it seems to me that this is only a problem if you don’t know which track you are on before the first 0.5 track step is taken by the loader. |
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Krill
Registered: Apr 2002
Posts: 2981 |
Quoting SpartaPlease correct me if I’m mistaken but it seems to me that this is only a problem if you don’t know which track you are on before the first 0.5 track step is taken by the loader. Well seems to me that generally you don't know which track you're on right after a reset/powercycle. =) |
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Martin Piper
Registered: Nov 2007
Posts: 726 |
Quote: Quoting SpartaPlease correct me if I’m mistaken but it seems to me that this is only a problem if you don’t know which track you are on before the first 0.5 track step is taken by the loader. Well seems to me that generally you don't know which track you're on right after a reset/powercycle. =)
And until the disk spins, a GCR sync mark is found, the GCR header is read, decoded, and the track and sector bytes are discovered. :) |
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