Welcome, Guest. Please login or register.


Author Topic: Creating EXDOS card clone (Read 30696 times)

Offline gflorez

  • EP addict
  • *
  • Posts: 2663
  • Country: es
  • OS:
  • Windows 7/Server 2008 R2 Windows 7/Server 2008 R2
  • Browser:
  • Firefox 66.0 Firefox 66.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #165 on: 2019.May.24. 09:55:56 »
A lot of time has passed, but it is good to complete information.

That link from Zozo follows to other link to a picture of three defective Philipines Z80 chips. On that thread I told about a lot of problems found while expanding a Microteam expansion card.

Later, I took out that Z80 to do a turbo hack on my computer. This is the back of the removed processor:

23517-0

My other EP was also in time modified to turbo, but it had a SGS Z80 clone installed.
« Last Edit: 2019.May.24. 10:00:00 by gflorez »

Offline pear

  • EP lover
  • *
  • Posts: 783
  • Country: pl
  • Z80 only
  • OS:
  • Windows NT 6.3 Windows NT 6.3
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #166 on: 2019.May.24. 10:42:19 »
As for the Z80 processors, the cause is known.
There were a series of processors with a damaged M1 line (or damaged in exploatation, in ZX Spectrum M1 is near a +9V power line on the edge connector).
From my observations, the M1 signal can be damaged in two ways:
The first - the M1 line is completely dead;
Second - the frequency on the M1 line is half as high as it should be (the correct frequency is between the CPUclk/7 and the CPUclk/4).
Both cause problems in interfaces that use the M1 signal.

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13521
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Creating EXDOS card clone
« Reply #167 on: 2019.May.24. 11:32:51 »
Yes I know about ZX-M1 problem. But on the Enterprise the Dave already use the M1 for set memory waits, then immediately can notice if it is not working.
And on Spectrum M1 used for a "overwrite ROM" trick, executed address decoded in ROM, and the expansion page in their ROM, for modifi the original ROM program. This is the only way expand the closed system of Spectrum.
This trick don't needed on EP, because the EXOS have a nice expansion possibilities.

The bad Z80s what I noted: can't write to memory! Can read memory, can execute program, can read IO, can write IO... just memory write don't work... some are total, some are unreliable. All are from machine which is worked, stored for a few decades, and don't start now.
The problematic ones what Gflorez mentioned have a problem with memory expansions, especially with modern Flash/SRAM chips.
I think will be possible if retesting these chips after 5-10 years, then there is a completly no memory write problem...
It is a theory: plastick package of chips sometime not fully hermetic and the chip parts can corrode over the decades. Some lower quality production serie will make series of similar faults in a similar chips.
Similar example the Newtronics dead head problems in Commodore 1541 drives.


Offline pear

  • EP lover
  • *
  • Posts: 783
  • Country: pl
  • Z80 only
  • OS:
  • Windows 7/Server 2008 R2 Windows 7/Server 2008 R2
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #168 on: 2019.May.26. 21:44:16 »
The seller demanded to prove that the chips have a defect.
So I prepared a movie.
Have a nice watch.

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13521
  • Country: hu
  • OS:
  • Windows 7/Server 2008 R2 Windows 7/Server 2008 R2
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Creating EXDOS card clone
« Reply #169 on: 2019.May.26. 22:38:07 »
Very interesting!
Just for curiosity: what happen with two drives, COPY from one full disk to empty, formated disk?

Offline pear

  • EP lover
  • *
  • Posts: 783
  • Country: pl
  • Z80 only
  • OS:
  • Windows NT 6.3 Windows NT 6.3
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #170 on: 2019.May.27. 05:49:52 »
When the diskette is formatted, everything is fine.
The faulty series can not only format floppy disks.

But I'm not sure what will happen when copying a file that takes, for example, half a floppy disk or more.

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13521
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Creating EXDOS card clone
« Reply #171 on: 2019.May.28. 16:14:13 »
I digged out two Korean VL chip:
This one, with 1988 w13 date code, works normaly.
23538-023540-1

Another one from my bad chips box, date code 1987 w02. Looks same with Pear chip!
23542-223544-3
And probably same fault?
I also made some videos (head step too quiet, turn up volume :-) )
EXDOS FORMAT
The head many times go out to Track 0. Then overwrite previous tracks, not a surprise the Sector not found at the end...
Probably sometimes Restore command executed instead the Step In?

EPDOS formating. Total crazy, the head most of time restored to tr0...

FAFO formating. Works normally :ds_icon_cheesygrin: I don't know yet which are help: using my own WD177x routines instead of EXDOS DISKIO? Or just the reverse direction formating, where Step Out used instead the Step In?

Next test is a copy:
COPY disk to RAMDISK, with a good chip. Normal head movement, go to tr0 only for a next FAT or root DIR sector or file entry.

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.

I also tried EPDOS copy, it is generate many Sector not found error, and press Retry to continue. (No auto retry mechanism) I think this is why I putted this chip to the "bad chips box" many years ago.
« Last Edit: 2019.May.28. 16:20:07 by Zozosoft »

Offline pear

  • EP lover
  • *
  • Posts: 783
  • Country: pl
  • Z80 only
  • OS:
  • Windows 7/Server 2008 R2 Windows 7/Server 2008 R2
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #172 on: 2019.May.28. 17:48:19 »
Are you sure those 813 V L657S are working ?
Because I can to exchange them.

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13521
  • Country: hu
  • OS:
  • Linux Linux
  • Browser:
  • Chrome 74.0.3729.157 Chrome 74.0.3729.157
    • View Profile
    • http://enterprise.iko.hu/
Re: Creating EXDOS card clone
« Reply #173 on: 2019.May.28. 18:13:57 »
Also tested it today and worked normally. Tomorrow i can make few hours more testing.

Offline pear

  • EP lover
  • *
  • Posts: 783
  • Country: pl
  • Z80 only
  • OS:
  • Windows 7/Server 2008 R2 Windows 7/Server 2008 R2
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #174 on: 2019.May.28. 18:28:04 »
I will be grateful :)

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13521
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Creating EXDOS card clone
« Reply #175 on: 2019.May.29. 10:47:59 »
Tested it for about two hours. Dozen disk formated, also including 10 and 11 sectors format, both with EXDOS and EPDOS. Disks copied with COPY, EPDOS Copy and Diskcopy. Working flawlessly.

Offline pear

  • EP lover
  • *
  • Posts: 783
  • Country: pl
  • Z80 only
  • OS:
  • Unknown Unknown
  • Browser:
  • Firefox 68.0 Firefox 68.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #176 on: 2019.May.29. 10:58:46 »
Thanks

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13521
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Creating EXDOS card clone
« Reply #177 on: 2019.June.03. 23:01:44 »
FAFO formating. Works normally :ds_icon_cheesygrin: I don't know yet which are help: using my own WD177x routines instead of EXDOS DISKIO? Or just the reverse direction formating, where Step Out used instead the Step In?

I asked Bruce for make a EXDOS 3 test version with a reverse direction FORMAT.
There is the results, with the bad VL chip.
After few track the head restored to Track 0. Because the disk are previously formated, then the verify phase also can run. It is many time reseting the head, but the diskio auto retry handle the problems.

Summary: the problem don't depend from which Step (In or Out) used. But still there is the big question: how possible the FAFO are working with these bad chip? :oops:

Offline pear

  • EP lover
  • *
  • Posts: 783
  • Country: pl
  • Z80 only
  • OS:
  • Windows NT 6.3 Windows NT 6.3
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
Re: Creating EXDOS card clone
« Reply #178 on: 2019.June.04. 05:52:39 »
I have a theory.
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 ?

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13521
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 67.0 Firefox 67.0
    • View Profile
    • http://enterprise.iko.hu/
Re: Creating EXDOS card clone
« Reply #179 on: 2019.June.04. 09:56:19 »
The defective VL works properly in the Timex FDD3000 disk drive.
Least one place where it is working :-)

Quote
In the original, WD1770 was used there.
EXDOS originaly also use 1770.


Quote
Maybe your FAFO works a little slower than the original FORMAT ?
No, it is FAst FOrmat :-)
But very possible some timing are different. I wrote my 177x routines from a Enterpress article. Now I know it is a summary of WD datasheet. It is talked abaout command codes, but don't too much about timing. Then I set these by practical experience. For example the article don't talked about need to wait after write command for can read status. It is a surprise for me :-) Then I putted some PUSH/POP for a waits. Is possible some better codes, which is used the original datasheet, have a shorter waits because use the exact timings.