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Author Topic: Creating EXDOS card clone (Read 28884 times)

Online Zozosoft

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Re: Creating EXDOS card clone
« Reply #180 on: 2019.June.06. 10:58:26 »
Same COPY with the bad chip. There is some extra head movement. The EXDOS retry mechanism handled it, no error, just about 15-16 secs longer the operation than the normal.
Update: it is only with EXDOS 3, with EXDOS 1.x about 35 Not read question during the COPY :oops:

Online Zozosoft

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Re: Creating EXDOS card clone
« Reply #181 on: 2019.June.06. 13:22:15 »
The defective VL works properly in the Timex FDD3000 disk drive.
In the original, WD1770 was used there.
Perhaps the faulty VL have a problem with stabilizing parameters when working with shorter access times ?
Maybe your FAFO works a little slower than the original FORMAT ?
I think I found the problem:
The Seek command don't reliable these faulty chips. Sometimes execute Restore instead of Seek (only one bit difference in command code!)
My FAFO only using Step In/Out commands, when Seek needed it is done by steps cycle.
EXDOS FORMAT use DISKIO calls which is use a general head positioning routine. It is don't care about if only one track step needed, always using the Seek command.

Probably that Timex drives also only use Step commands. There is disassembly of their ROM?

If my theory right then the faulty chips also will works with the Hungarian SpeccyDOS disk interface (for a ZX Spectrum), least with 4S ROM (it is developed for a old slow drives, where the 1772 step rates too fast. This ROM using Step cycles with a CPU delays for simulate the different step rates from 2 to 30ms).

Offline pear

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Re: Creating EXDOS card clone
« Reply #182 on: 2019.June.10. 06:14:01 »
Probably that Timex drives also only use Step commands. There is disassembly of their ROM?
It looks like it is :)
Code: ASM
  1. ;==================================================================================================
  2. ; L29b0 Format next track (step in, format)
  3. ;
  4. ;==================================================================================================
  5. L29b0:  ld   a,$01
  6.         ld   ($26a1),a
  7.         ei  
  8.         ld   a,$58
  9.         out  ($c0),a    ; command $58 - step-in, update track register, spin up
  10.         halt
  11.         halt
  12.         halt            ; wait 3 tracks
  13.  

and then $fe - write track, no spinup, 30ms delay, no precomp

Online Zozosoft

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Re: Creating EXDOS card clone
« Reply #183 on: 2019.August.10. 21:45:40 »
Are you sure those 813 V L657S are working ?
Because I can to exchange them.
What happen finaly with your chips?

After some investigation now it is sure: the Seek command are the problematic in the fauilty VL1772 chips. Sometimes execute Restore instead of Seek.

To the DRVTEST (will be released soon) added a verification for a Seek commands, and report error if the head went to Track 0 when it is not expected. Then easy to see if the chip faulty.
At a manual seeks:
23785-0

During a test cycle:
23787-1

Test ended with tons of errors:
23789-2

Bruce built in a alternative seek mode to the program, which is use cycle of step command, it is called Stepseek mode.
In this mode the faulty chip works correctly:
23791-3

This mode will be built in to the EXDOS 3, then it is can work with these faulty chips.

Meanwhile I found another bad chip, got it from a Commodore 1571 drive (where probably no anyone using the MFM mode in the last 30 years :-D ). It is have a 1986 week 33 datacode.
23793-4

Now I ordered cheap 5x pack WD1770 from a Aliexpress Let's see these are working or not :-)

Offline pear

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Re: Creating EXDOS card clone
« Reply #184 on: 2019.August.21. 09:43:19 »
Finally, the seller replaced the faulty chips with other from 813V L657S series.
This series works fine. I checked all the pieces.
For a change, IMO, they makes too hot. I did not check to what temperature.
It is possible that overheating will cause some errors, but this should be carefully checked.

Online Zozosoft

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Re: Creating EXDOS card clone
« Reply #185 on: 2019.August.21. 09:59:20 »
Finally, the seller replaced the faulty chips with other from 813V L657S series.
This series works fine. I checked all the pieces.
Great news!

Quote
For a change, IMO, they makes too hot. I did not check to what temperature.
Yes, it is a know the VL are more hot than WD.

Quote
It is possible that overheating will cause some errors, but this should be carefully checked.
But this is only make a problem when overclocking to 16MHz for using a HD disks.
For example there is Pertik Laci's Turbo EXDOS card, he are used a fan on the card. When VL1772 overclocked.
Few years ago it is replaced by WD1772, then fan not required even using a HD disks.
(The Turbo EXDOS 1.3 ROM left the last used clock on the chip. In a EXDOS 3 only at R/W operation used the turbo clock, then switch back to the normal 8MHz, for a less stress on the controller chip, and also solve the step rate problem.)

On a normal DD usage don't problem with VL. (with a good chips :-) )
I read same experiences at Atari ST forums.

Online gflorez

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Re: Creating EXDOS card clone
« Reply #186 on: 2019.August.21. 10:06:26 »
I also observed over-heating on some clones I bought on USA to the Atari supplier.
« Last Edit: 2019.August.28. 16:37:54 by gflorez »

Online Zozosoft

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Re: Creating EXDOS card clone
« Reply #187 on: 2019.August.23. 19:38:32 »
8921 date coded also looks good, tested two of them.
23849-0
23851-1

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Re: Creating EXDOS card clone
« Reply #188 on: 2019.August.27. 19:30:45 »
This version of VL1772 works best.
Without errors. No overheating.

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Re: Creating EXDOS card clone
« Reply #189 on: 2019.August.27. 20:02:01 »
This version of VL1772 works best.
Nice young one :-) Manufactured in 1992.
It is one piece find? Or still available in somewhere?

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Re: Creating EXDOS card clone
« Reply #190 on: 2019.August.27. 20:18:10 »
I bought 20 pieces a few years ago.

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Re: Creating EXDOS card clone
« Reply #191 on: 2019.October.09. 21:50:55 »
Now I ordered cheap 5x pack WD1770 from a Aliexpress Let's see these are working or not :-)
Arrived :ds_icon_cheesygrin:
Extreme slow shipping, more than 1 month until the seller dispatched it... plus the usual shipping time from China.
But it was worth the wait!

These are really NOS chips :!: , not a relabeled/refurbished/fake what I expected :lol:
All working normally.
24017-024019-1
24021-224023-3

Online gflorez

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Re: Creating EXDOS card clone
« Reply #192 on: 2019.October.10. 01:07:18 »
Great opportunity!