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Home » RBC Forums » General Discussion » N8 SBC 3.5" Floppy Support (Discussion about interesting errors with the N8 Floppy Implementation)
N8 SBC 3.5" Floppy Support [message #9392] Wed, 17 November 2021 23:24 Go to next message
drj113 is currently offline  drj113
Messages: 6
Registered: July 2017
Junior Member
Hi Everybody,

I am really enjoying playing with my newest favourite little N8 machine (Shhh - Don't tell my Pulsar Little Big Board).

SD Card support Just works, and its being really reliable.

I have an interesting problem with the Floppy Disk.

I am using a 3/5" FDD with 1.44Mb disks. I can format it with FDU, but when I attempt to formal at 1.44Mb, I see the following when I format a track:

===== N8 ==============<< FDU MAIN MENU >>======================
(S)ETUP: UNIT=00 MEDIA=1.44MB MODE=POLL TRACE=00
------------------------------------------------------------ ----
(R)EAD (W)RITE (F)ORMAT (V)ERIFY
(I)NIT BUFFER (D)UMP BUFFER FDC (C)MDS E(X)IT
=== OPTION ===> FORMAT (T)RACK, (D)ISK ===> TRACK
ENTER TRACK [00-4F] (00):
ENTER HEAD [00-01] (00):
ENTER INTERLEAVE [01-12] (02):



RESET DRIVE...
PROGRESS: TRACK=00 HEAD=00 SECTOR=01

No errors appear

But when I attempt to verify, I see this:
===== N8 ==============<< FDU MAIN MENU >>======================
(S)ETUP: UNIT=00 MEDIA=1.44MB MODE=POLL TRACE=00
------------------------------------------------------------ ----
(R)EAD (W)RITE (F)ORMAT (V)ERIFY
(I)NIT BUFFER (D)UMP BUFFER FDC (C)MDS E(X)IT
=== OPTION ===> VERIFY (S)ECTOR, (T)RACK, (D)ISK, (R)ANDOM ===> TRACK
ENTER TRACK [00-4F] (00): 00
ENTER HEAD [00-01] (00):


PROGRESS: TRACK=00 HEAD=00 SECTOR=01
DATA MISMATCH AT 0000
CONTINUE? (A)BORT, (R)ETRY, (I)GNORE ===>

I have tried multiple media with no success.

Interestingly, if I lie and set the drive to be a 5.25" HD drive, I format and verify with no errors. I can copy a heap of files with PIP, but I can't SYSGEN the resulting disk.

If anybody has any advice it would be very much appreciated.

Doug

Re: N8 SBC 3.5" Floppy Support [message #9424 is a reply to message #9392] Thu, 25 November 2021 11:28 Go to previous message
Wayne W is currently offline  Wayne W
Messages: 385
Registered: October 2015
Location: Fallbrook, California, US...
Senior Member
Hi Doug,

The verify command in FDU is really stupid. I am allowed to say that since I wrote it. The verify compares the data read from the sector with whatever is in the buffer. You must fill the buffer with the correct data before doing a verify. In your case, just use the buffer fill command to set all bytes of the buffer to 0xE5 which is the value used on the format command. The verify should then work fine.

Sorry for the slow reply.

Wayne
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