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IBM XT 5160 System error 20?

F

fjk61011

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Joined
Nov 18, 2009
Messages
1,724
Location
Dublin, Ireland
Configuration:

Memory card
Parallel port card
VGA card
WDXT GEN2 card
XT-FDD
serial card

I get system error 20 and a continue prompt
Continue and POST beep
 
Removing XT-IDE card and system boots to Post and loads DOS from HDD.

Installed FDC and 360Kb FDD and system works fine.
 
On screen System Error 20

Memory card
Parallel port card Xircom PE3
VGA card
WDXT GEN2 card and IBM TYPE 2 20 Mb
serial card
FD controller and 360 kb fdd
XT-IDE with DOS 6.22 and mTCP.

If I'm quick enough pressing D I can get 6.22 booted from Drive D: and access IBM TYPE 2 20 Mb as C:

No System Error 20 in this setup.
 
Off topic but .....

I have two packets of new 5.25" floppy disks, one packet is DD and the other is HD. Unformatted.

No labels. Are these disks identical until formatted? If not, how would I tell which are DD and which HD?

I dropped some.
 
Other than manufacturer's labels, I suppose that you could try formatting them. DD ones generally don't format well as HD. Generally, DD ones without hub reinforcing rings are either (a) very old or (b) intended for use in DEC RX50 drives (96 tpi DD).
 
I've formatted a reinforcing floppy in a Tandon successfully. Copied some files to it and read them back using DIR (360 kb).

Was able to read it in a 1.2 Mb FDD.
 
Last edited:
Hello,

To my eyes, the HD disks always seem more black, and more highly polished, then the DD disks. More important, if I hold the disks up to a bright light, the HD disks seem more transparent, i.e. there is a hint of the light visible, while the DD disks are usually totally opaque and none (or clearly much less) of the point of light is visible.

The formatting/reading etc is not reliable. Both types can often be formatted as the other, and data can be written, and read back. The important fact though is how reliable the write is, i.e. will it still read OK in nn months time. Chances are it will NOT.

Geoff
 
LIke the 3.5" disks, HD used smaller particle size and thinner coating, so a visual inspection (hold the thing up to the light) might give some clues.

The key difference in the 5.25" is the coercivity of the medium. Can you format a disk in HD, then reformat it in DD and vice versa? A "virgin" HD disk can often be formatted as DD, but not after it's been formatted in HD. HD writing uses higher write currents.

With respect to 3.5" HD, the difference in coercivity from DD is not nearly as great, which means that HD 3.5" disks will often be very stable, formatted as DD.
 
I've been able to format 360 kb floppies and copy mTCP files from a DOM on an xtide card. Using those floppies i copied those files to the 20 Mb hdd. using the xt-ide I'm able to connect to the internet using mTCP. With the 20 Mb hdd I can't connect so there must be a conflict with the xt-ide controller and something else
 
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