help with disk system

Started by wimvdb, January 10, 2019, 11:31:29 am

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wimvdb

hey,

I am working to get a FDS in working condition. But now I got stuck. I was able to align the head but the disk keeps throwing error codes. But when I lay a disk without the black disk cradle into the FDS it works. I reattach the cradle and it no longer works. The head moves also slower and seems to get stuck or something then moves on, hangs again ... and in the end again an error.

Could someone help me find the cause and get it to work as it shout?

thanks,
Wim

theoakwoody

Use zmaster18.  I had tried for years to replace my belt and get my fds up and running following every guide I could find. He got it up and running in no time and his pricing is very fair.  Had it done a year ago and it's still going strong.

https://www.famicomworld.com/forum/index.php?topic=13885

wimvdb


boye


wimvdb


boye

Errors 22 and 27 most likely mean that the motor-spindle alignment is off.
Error 20 is "Screen data differs", whatever that means.

P

Error 20 means that the KYODAKU-file is missing (the data for the license text that scrolls up when booting a disk). But any of those errors around 20 are quite unreliable and often happens when something is funny with either the disk or the head/motor. So the error codes aren't THAT useful.

80sFREAK

Quotemotor-spindle alignment

Please, not this shit again. This errors has nothing to do with spindle.
I don't buy, sell or trade at moment.
But my question is how hackers at that time were able to hack those games?(c)krzy

boye

Quote from: 80sFREAK on January 22, 2019, 06:45:33 am
Quotemotor-spindle alignment

Please, not this shit again. This errors has nothing to do with spindle.

Please clarify.

80sFREAK

January 22, 2019, 09:32:42 am #9 Last Edit: January 22, 2019, 09:43:38 am by 80sFREAK
Quote from: wikipediaQuick Disk as used in the Famicom Disk System holds 64 kB of data per side, requiring a manual turn-over to access the second side.

Unusually, the Quick Disk utilizes "a continuous linear tracking of the head and thus creates a single spiral track along the disk similar to a record groove."[51] This has led some to compare it more to a "tape-stream" unit than typically what is thought of as a random-access disk drive

Spiral track. To figure out, where is the "start position" of the spiral track, there is a switch, flipped, when head moving away from centre.

There is a glitch, when this switch can't flip(or oxidated contacts), disk will spin endlessly with black screen. There is no "time out" in BIOS ROM. System will wait forever for "start position" signal. I will disassemble ROM and put some comments on this section of the code. Someday.

To "decalibrate" headunit (not spindle LOL) unscrew circuit board(start position switch soldered there), shift it little bit and screw back. This happening, when you changing belt. Sometimes you are lucky to set PCB on the right place, sometimes you don't.

Keep in mind, that track is spiral, so the matter is where head placed, relatively to excentric disc, which shifting head unit. There is a bolt, loaded with a spring, for adjustment. Easy to access, easy to adjust.
I don't buy, sell or trade at moment.
But my question is how hackers at that time were able to hack those games?(c)krzy

P

Quote from: 80sFREAK on January 22, 2019, 09:32:42 am
There is a glitch, when this switch can't flip(or oxidated contacts), disk will spin endlessly with black screen. There is no "time out" in BIOS ROM. System will wait forever for "start position" signal. I will disassemble ROM and put some comments on this section of the code. Someday.

You mean this is a software bug in the BIOS (unless pins are corroded)?

Quote from: 80sFREAK on January 22, 2019, 09:32:42 am
To "decalibrate" headunit (not spindle LOL) unscrew circuit board(start position switch soldered there), shift it little bit and screw back. This happening, when you changing belt. Sometimes you are lucky to set PCB on the right place, sometimes you don't.

Keep in mind, that track is spiral, so the matter is where head placed, relatively to excentric disc, which shifting head unit. There is a bolt, loaded with a spring, for adjustment. Easy to access, easy to adjust.

Isn't it the head bolt that screw with glue on it that you shouldn't normally touch unless someone else messed with it? The source of faulty home-written disks.

80sFREAK

January 24, 2019, 02:46:36 am #11 Last Edit: January 24, 2019, 03:06:12 am by 80sFREAK
I would call it feature. BIOS waiting for "disk ready" and it is not happening :) There is no other way the system can recognise "start track". There is three bits in $4032

Quote from: EnriBit2:/WRITE_PROTECT 1=カード書き込み禁止  、0=カード書き込み可
Bit1:/READY         1=内部に移動している  、0=スタート位置
Bit0:/MEDIA_SET     1=セットされていない  、0=セットされた


Or nesdev wiki

Disk drive status register ($4032)

7  bit  0
---------
xxxx xPRS
      |||
      ||+- Disk flag  (0: Disk inserted; 1: Disk not inserted)
      |+-- Ready flag (0: Disk read; 1: Disk not ready)
      +--- Protect flag (0: Not write protected; 1: Write protected or disk ejected)


I think here it is
LE678:LDX #$01
      LDA $4032
      LSR A      ;LSR shifts all bits right one position. 0 is shifted into bit 7 and the original bit 0 is shifted into the Carry.
      JSR LE77C
      LSR A      ;one more time, so C=bit1, Ready flag (0: Disk read; 1: Disk not ready)
      BCS LE678 ;branch if C=1
      RTS


This bolt is for calibrating head unit.
I don't buy, sell or trade at moment.
But my question is how hackers at that time were able to hack those games?(c)krzy

P

I see then I wouldn't really call it a software bug.