OSDev.org

Posted: **Mon Jun 23, 2025 4:09 pm**

Hi there. I was playing with it and changing to experiment and confused myself.

I've fixed things and this is the new read below. Some parts are correct but occasionally corrupt. But also, there are only around 9 sectors written, and the sector numbers are all 9F instead of goes from 1 to 16. And finally theres a bunch of filler data FF at the beginning and end which is wrong...

Can you see any patterns in this? I know that the 369 filler bytes go overboard at the end, and then it overwrites the beginning of the track as well. But the status register is clear after all this so it does not report errors.

0000 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0010 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0020 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0030 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0040 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0050 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0060 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0070 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0080 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0090 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
00A0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
00B0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
00C0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
00D0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
00E0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
00F0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0100 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0110 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0120 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0130 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0140 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0150 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0160 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0170 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0180 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0190 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
01A0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
01B0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
01C0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
01D0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
01E0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
01F0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0200 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0210 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0220 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0230 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0240 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0250 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0260 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0270 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0280 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0290 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
02A0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
02B0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
02C0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
02D0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
02E0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
02F0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0300 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0310 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0320 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0330 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0340 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0350 FF FF FF FF FF FF FF FF CB CB CB CB CB CB CB CB ................
0360 CB CB CB 1D C3 FF FF FF FF FF FF FF FF FF FE 00 ................
0370 00 00 00 00 01 FF 00 00 9F 00 E9 27 FF FF FF FF ...........'....
0380 FF FF FF FF FF FF FF 00 00 00 00 00 00 FB E5 E5 ................
0390 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03D0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03E0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0400 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 ..............]0
0410 FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 ................
0420 FE 00 00 9F 00 E9 27 FF FF FF FF FF FF FF FF FF ......'.........
0430 FF FF 00 00 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 ................
0440 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0450 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0460 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0470 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0480 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0490 E5 E5 E5 E5 E5 E7 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
04A0 E5 E5 E5 E5 E7 E5 E5 E5 E5 E5 E5 E5 E7 E5 E7 E5 ................
04B0 E5 E5 E5 E5 E7 E5 E5 E5 E5 5D 30 FF FF FF FF FF .........]0.....
04C0 FF FF FF FF FF 00 00 00 00 00 00 FE 00 00 9F 00 ................
04D0 E9 27 FF FF FF FF FF FF FF FF FF FF FF 00 00 00 .'..............
04E0 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
04F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0500 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0510 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0520 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0530 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0540 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0550 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0560 E5 E5 F5 E5 DF 75 FF FF FF FF FF FF FF FF FF FF .....u..........
0570 00 00 00 00 00 00 FF 00 00 9F 00 E9 27 FF FF FF ............'...
0580 FF FF FF FF FF FF FF FF 00 00 00 00 00 00 FB E5 ................
0590 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05D0 E5 E5 E5 E5 E5 E5 E5 E5 E7 E5 E7 E5 E7 E5 E7 E5 ................
05E0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0600 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D ...............]
0610 30 FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 0...............
0620 00 FE 00 00 9F 00 E9 27 FF FF FF FF FF FF FF FF .......'........
0630 FF FF FF 00 00 00 00 00 00 FB E5 E5 E5 E5 E5 E5 ................
0640 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0650 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0660 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0670 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0680 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0690 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
06A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
06B0 E5 E5 E5 E5 E5 E5 E5 E5 F5 E5 DD 31 FF FF FF FF ...........1....
06C0 FF FF FF FF FF FF 00 00 00 00 00 00 FE 00 00 9F ................
06D0 80 E9 27 FF FF FF FF FF FF FF FF FF FF FF 00 00 ..'.............
06E0 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
06F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0700 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0710 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0720 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0730 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0740 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0750 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0760 E5 E5 E5 E5 E5 5D 30 FF FF FF FF FF FF FF FF FF .....]0.........
0770 FF 00 00 00 00 00 00 FE 00 00 9F 00 E9 27 FF FF .............'..
0780 FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 FB ................
0790 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
07A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
07B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
07C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
07D0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
07E0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
07F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0800 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 F5 E5 ................
0810 DF 75 FF FF FF FF FF FF FF FF FF FF 00 00 00 00 .u..............
0820 00 00 FF 00 40 9F 80 E9 27 FF FF FF FF FF FF FF ....@...'.......
0830 FF FF FF FF 00 00 00 00 00 00 FB E5 E5 E5 E5 E5 ................
0840 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0850 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0860 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0870 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0880 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0890 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
08A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
08B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 FF FF FF ...........]0...
08C0 FF FF FF FF FF FF FF 00 00 00 00 00 00 FE 00 00 ................
08D0 9F 00 E9 27 FF FF FF FF FF FF FF FF FF FF FF 00 ...'............
08E0 00 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
08F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0900 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0910 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0920 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0930 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0940 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0950 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0960 E5 E5 E5 F5 E5 E5 DD 31 FF FF FF FF FF FF FF FF .......1........
0970 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0980 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0990 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
09A0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
09B0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
09C0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
09D0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
09E0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
09F0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A00 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A10 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A20 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A30 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A40 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A50 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A60 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A70 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A80 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0A90 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AA0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AB0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AC0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AD0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AE0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AF0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B00 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B10 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B20 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B30 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B40 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B50 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B60 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B70 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B80 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B90 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BA0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BB0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BC0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BD0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BE0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BF0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................

Posted: **Mon Jun 23, 2025 5:40 pm**

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pmthe sector numbers are all 9F instead of goes from 1 to 16.

Is that because your code sets the sector number to 0x9F, or because there's something wrong with how the WD1770 is connected to your CPU?

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pm0350 FF FF FF FF FF FF FF FF CB CB CB CB CB CB CB CB ................

This appears to be the middle of a sector full of 0xE5 bytes. It took the WD1770 a surprisingly long time to lock onto a valid data signal. Are you sure your drive is rotating at the correct speed when the WD1770 starts reading or writing the disk? Are you using the right type of disk? (HD disks will not work in SD/DD drives.) This seems too far into the track to be a write splice, but maybe check to see if your drive is producing appropriate index pulses.

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pm0370 00 00 00 00 01 FF 00 00 9F 00 E9 27 FF FF FF FF ...........'....

Several of the sector IDs, including this one, appear to have some flipped bits. All of the sector IDs have the same CRC, so it looks like your disk just isn't holding the data correctly. Some of the sector data also has flipped bits. However...

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pm0560 E5 E5 F5 E5 DF 75 FF FF FF FF FF FF FF FF FF FF .....u..........

...Some of the sector data has a completely different CRC. The WD1770 calculates this CRC automatically based on the data it writes to the disk, which means the WD1770 itself thinks it's writing different data than you expect. I don't know if that means there's still a problem with how it's interfaced to your CPU, some kind of analog issue like power sagging, or a faulty chip.

Posted: **Mon Jun 23, 2025 5:55 pm**

Octocontrabass wrote: ↑Mon Jun 23, 2025 5:40 pm
AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pmthe sector numbers are all 9F instead of goes from 1 to 16.
Is that because your code sets the sector number to 0x9F, or because there's something wrong with how the WD1770 is connected to your CPU?

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pm0350 FF FF FF FF FF FF FF FF CB CB CB CB CB CB CB CB ................
This appears to be the middle of a sector full of 0xE5 bytes. It took the WD1770 a surprisingly long time to lock onto a valid data signal. Are you sure your drive is rotating at the correct speed when the WD1770 starts reading or writing the disk? Are you using the right type of disk? (HD disks will not work in SD/DD drives.) This seems too far into the track to be a write splice, but maybe check to see if your drive is producing appropriate index pulses.

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pm0370 00 00 00 00 01 FF 00 00 9F 00 E9 27 FF FF FF FF ...........'....
Several of the sector IDs, including this one, appear to have some flipped bits. All of the sector IDs have the same CRC, so it looks like your disk just isn't holding the data correctly. Some of the sector data also has flipped bits. However...

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 4:09 pm0560 E5 E5 F5 E5 DF 75 FF FF FF FF FF FF FF FF FF FF .....u..........
...Some of the sector data has a completely different CRC. The WD1770 calculates this CRC automatically based on the data it writes to the disk, which means the WD1770 itself thinks it's writing different data than you expect. I don't know if that means there's still a problem with how it's interfaced to your CPU, some kind of analog issue like power sagging, or a faulty chip.

I am using the drive in single density FM mode, but my disks are high density. Is this a problem? My drives are single sided drives, but they can write double density. I am using single density mode. The drive seems to be rotating normally...

Because of the fact that many times it writes the correct bytes, I don't think this is a problem of how I wired the chip. If that was so it would happen for pretty much every byte? It writes many bytes correctly. I am puzzled. I suspect my CPU is being too slow, so I will try optimizing the code to make it tighter. I am out of ideas. Does this chip need a decoupling capacitor 100%? Those bit flips are suspicious. I am not using decoupling as I've never had a situation of needing them and this chip is NMOS not TTL...

Posted: **Mon Jun 23, 2025 6:28 pm**

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 5:55 pmI am using the drive in single density FM mode, but my disks are high density. Is this a problem?

For 5.25" disks/drives, yes. A drive designed for SD/DD disks won't properly magnetize HD disks.

Posted: **Tue Jun 24, 2025 2:00 am**

AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 5:55 pmDoes this chip need a decoupling capacitor 100%? Those bit flips are suspicious. I am not using decoupling as I've never had a situation of needing them and this chip is NMOS not TTL...

If it's through-hole, maybe hook an oscilloscope to the power and ground pins. I don't know, I never got around to practicing analog electronics, I'm just guessing at what might help. But I had a suspicion about CPU speed when I read the first few posts of this thread, so... Actually, an oscilloscope on a data line could tell you whether the CPU is sending data fast enough. Just send alternate bytes; repeating 55 AA will toggle every data line.

Posted: **Tue Jun 24, 2025 11:30 am**

Octocontrabass wrote: ↑Mon Jun 23, 2025 6:28 pm
AnalogChipDesigner wrote: ↑Mon Jun 23, 2025 5:55 pmI am using the drive in single density FM mode, but my disks are high density. Is this a problem?
For 5.25" disks/drives, yes. A drive designed for SD/DD disks won't properly magnetize HD disks.

My drive can do both SD and DD. Does that also mean it cannot properly magnetize? Someone else told me there are no problems. Are you sure?

Posted: **Tue Jun 24, 2025 12:33 pm**

https://www.brutman.com/Diskettes/Diske ... dling.html

Posted: **Tue Jun 24, 2025 12:56 pm**

AnalogChipDesigner wrote: ↑Tue Jun 24, 2025 11:30 amMy drive can do both SD and DD. Does that also mean it cannot properly magnetize?

Yes. 5.25" HD disks require a much stronger electromagnet than 5.25" SD/DD disks.

AnalogChipDesigner wrote: ↑Tue Jun 24, 2025 11:30 amSomeone else told me there are no problems. Are you sure?

Were they talking about 3.5" disks? A 3.5" HD disk will usually work in a 3.5" DD drive.

Posted: **Wed Jun 25, 2025 11:05 am**

Hey there.
I have an update.......... It feels like everyday I am 5% closer to getting it to work.

I decided to turn off one of the configuration bits that enables the "spinup sequence" for the drive. This bit makes the disc spin until 6 index pulses have passed by. I thought this would do no harm so I mostly left it on. But turning it off when I send the read track command, now I see the sectors where they should be!!
So leaving that bit on somehow is not compatible with this drive. I think the WD chip loses track of the index, or it starts the process middleway. But either way it fails with that ON.

Now I can get something that looks more like a correct track. But there are still errors in some of the bytes, and that I am still not sure why,,,

But here is an example track that is working better:

Code: Select all

0000 0B FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0010 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0020 FF FF FF FF FF FF FF FF FC 00 00 00 00 00 03 FE ................
0030 00 00 01 00 D2 C3 FF FF FF FF FF FF FF FF FF FF ................
0040 FF 00 00 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 ................
0050 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0060 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0070 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0080 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0090 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
00A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
00B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
00C0 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 FF FF FF FF FF FF ........]0......
00D0 FF FF FF FF 00 00 00 00 00 00 FE 00 00 02 00 87 ................
00E0 90 FF FF FF FF FF FF FF FF FF FF FF 00 00 00 00 ................
00F0 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0100 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0110 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0120 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0130 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0140 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0150 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0160 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0170 E5 E5 E5 5D 30 FF FF FF FF FF FF FF FF FF FF 00 ...]0...........
0180 00 00 00 00 00 FE 00 00 03 00 B4 A1 FF FF FF FF ................
0190 FF FF FF FF FF FF FF 00 00 00 00 00 00 FB E5 E5 ................
01A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
01B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
01C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
01D0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
01E0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
01F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0200 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0210 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 ..............]0
0220 FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 ................
0230 FE 00 00 04 00 2D 36 FF FF FF FF FF FF FF FF FF .....-6.........
0240 FF FF 00 00 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 ................
0250 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0260 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0270 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0280 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0290 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
02A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
02B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
02C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 FF FF FF FF FF .........]0.....
02D0 FF FF FF FF FF 00 00 00 00 00 00 FE 00 00 05 00 ................
02E0 1E 07 FF FF FF FF FF FF FF FF FF FF FF 00 00 00 ................
02F0 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0300 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0310 E5 E7 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E7 F5 ................
0320 E7 E5 E5 E5 E5 E7 E5 E7 E5 E7 E5 E5 E5 E5 E5 E7 ................
0330 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0340 E5 E5 E5 F5 F5 F5 F5 F7 F5 F5 F5 F5 F5 F5 F5 F5 ................
0350 F7 F5 F7 F5 F5 F5 F5 F5 F5 F7 F5 F5 F5 F5 F5 F7 ................
0360 F5 F7 F5 F5 F5 F5 F7 F5 F7 F5 F7 F7 F7 F7 F5 F7 ................
0370 F5 F7 F5 F7 5F 38 FF FF FF FF FF FF FF FF FF FF ...._8..........
0380 80 00 00 00 00 00 FE 00 00 06 00 4B F4 FF FF FF ...........K....
0390 FF FF FF FF FF FF FF FF 00 00 00 00 00 00 FB E5 ................
03A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03D0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03E0 E5 F5 E5 F5 E7 E5 E5 F5 E5 E5 E5 E5 E5 E5 E5 E5 ................
03F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0400 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0410 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 FD ................
0420 B0 FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 ................
0430 00 FF 00 00 07 80 78 77 FF FF FF FF FF FF FF FF ......xw........
0440 FF FF FF 80 00 00 00 00 00 FF F5 F7 F5 F7 F5 F7 ................
0450 F5 F7 F5 F7 F5 F7 F5 F7 F5 F5 E5 F5 E5 F5 E5 F7 ................
0460 E5 F7 E5 F5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0470 E5 E5 E7 E5 E7 E5 E7 E5 E7 E5 E5 E5 E5 E5 E5 E5 ................
0480 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0490 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
04A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
04B0 E5 E5 E5 E5 E5 E7 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
04C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 FF FF FF FF ..........]0....
04D0 FF FF FF FF FF FF 00 00 00 00 00 00 FE 00 00 08 ................
04E0 00 68 5B FF FF FF FF FF FF FF FF FF FF FF 00 00 .h[.............
04F0 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0500 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0510 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0520 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0530 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0540 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0550 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0560 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0570 E5 E5 E5 E5 E5 5D 30 FF FF FF FF FF FF FF FF FF .....]0.........
0580 FF 00 00 00 00 00 00 FE 00 00 09 00 5B 6A FF FF ............[j..
0590 FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 FB ................
05A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05D0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05E0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
05F0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0600 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0610 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0620 5D 30 FF FF FF FF FF FF FF FF FF FF 00 00 00 00 ]0..............
0630 00 00 FE 00 00 0A 00 0E 39 FF FF FF FF FF FF FF ........9.......
0640 FF FF FF FF 00 00 00 00 00 00 FB E5 E5 E5 E5 E5 ................
0650 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0660 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0670 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0680 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0690 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
06A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
06B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
06C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 FF FF FF ...........]0...
06D0 FF FF FF FF FF FF FF 00 00 00 00 00 00 FE 00 00 ................
06E0 0B 00 3D 08 FF FF FF FF FF FF FF FF FF FF FF 00 ..=.............
06F0 00 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0700 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0710 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0720 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0730 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0740 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0750 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0760 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0770 E5 E5 E5 E5 E5 E5 5D 30 FF FF FF FF FF FF FF FF ......]0........
0780 FF FF 00 00 00 00 00 00 FE 00 00 0C 00 A4 9F FF ................
0790 FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 ................
07A0 FB E5 F7 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 ................
07B0 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 E5 E5 F5 E5 E5 E5 ................
07C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 F5 E5 F5 E5 F5 E5 ................
07D0 F5 E5 E5 E5 F5 E5 F5 E5 F5 E5 F5 E5 E5 E5 E5 E5 ................
07E0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 F5 E5 F5 E5 ................
07F0 F5 E5 E5 E5 E5 E5 E5 E5 E5 F5 E5 F5 E5 F5 E5 E5 ................
0800 E5 E5 E5 E5 E5 E5 F5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0810 E5 E5 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 E5 E5 E5 ................
0820 E5 5D 30 FF FF FF FF FF FF FF FF FF FF 00 00 00 .]0.............
0830 00 00 00 FF 00 00 0D 00 97 AE FF FF FF FF FF FF ................
0840 FF FF FF FF FF 80 00 00 00 00 00 FB F5 E5 F5 E5 ................
0850 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 ................
0860 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 F5 E5 E5 E5 ................
0870 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0880 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0890 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
08A0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
08B0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
08C0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 FF FF ............]0..
08D0 FF FF FF FF FF FF FF FF 00 00 00 00 00 00 FE 00 ................
08E0 00 0E 00 C2 FD FF FF FF FF FF FF FF FF FF FF FF ................
08F0 00 00 00 00 00 00 FB E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0900 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0910 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0920 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0930 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0940 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0950 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0960 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0970 E5 E5 E5 E5 E5 E5 E5 5D 30 FF FF FF FF FF FF FF .......]0.......
0980 FF FF FF 00 00 00 00 00 00 FE 80 00 0F 00 F1 CC ................
0990 FF FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 ................
09A0 00 FB E5 E5 E5 E5 E5 E5 ED E7 ED E5 ED E5 ED E5 ................
09B0 ED E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
09C0 ED E5 ED E5 ED E7 ED E7 ED E5 E5 E5 E5 E5 E5 E5 ................
09D0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
09E0 E5 E5 E5 E5 ED E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
09F0 E5 E5 E5 E5 E5 E5 ED E7 ED E7 ED E5 ED E5 ED E7 ................
0A00 ED E7 ED E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0A10 ED E7 ED E5 ED E5 ED E5 ED E5 ED E5 E5 E5 E5 E5 ................
0A20 E5 E5 5D 30 FF FF FF FF FF FF FF FF FF FF 00 00 ..]0............
0A30 00 00 00 00 FE 00 00 10 00 E2 81 FF FF FF FF FF ................
0A40 FF FF FF FF FF FF 00 00 00 00 00 00 FB E5 E5 ED ................
0A50 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0A60 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0A70 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0A80 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0A90 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0AA0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0AB0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 ................
0AC0 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 5D 30 FF .............]0.
0AD0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AE0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0AF0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B00 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B10 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B20 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B30 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B40 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B50 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B60 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B70 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B80 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0B90 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BA0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BB0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BC0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BD0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BE0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0BF0 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0C00 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0C10 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................
0C20 FF FF FF FF FF FF FF FF FF

Posted: **Wed Jun 25, 2025 12:03 pm**

Octocontrabass wrote: ↑Tue Jun 24, 2025 12:56 pm
AnalogChipDesigner wrote: ↑Tue Jun 24, 2025 11:30 amMy drive can do both SD and DD. Does that also mean it cannot properly magnetize?
Yes. 5.25" HD disks require a much stronger electromagnet than 5.25" SD/DD disks.

AnalogChipDesigner wrote: ↑Tue Jun 24, 2025 11:30 amSomeone else told me there are no problems. Are you sure?
Were they talking about 3.5" disks? A 3.5" HD disk will usually work in a 3.5" DD drive.

I think 5.25"

But after some more research I realize you are right. Sorry about that.

I cannot however find any SD 5.25 disks. I can find some DD ones. ChatGPT says SD and DD were the same disks basically.
Do you confirm this?
I should really use DD disks instead then?

Because now I am managing to read a correct track but there are byte errors.... and I am wondering if it is because of what you said?

Posted: **Wed Jun 25, 2025 3:17 pm**

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 11:05 amI decided to turn off one of the configuration bits that enables the "spinup sequence" for the drive.

Setting that configuration bit disables the spinup sequence. It sounds like you were telling the WD1770 to read and write the disk without waiting for the drive to reach full speed!

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 12:03 pmChatGPT says

What's the point of asking fancy autocomplete if you don't know whether it gives you the right answer?

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 12:03 pmSD and DD were the same disks basically.
Do you confirm this?

There's no difference between SD and DD other than the data encoding. The disks are identical. The drives are identical.

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 12:03 pmI should really use DD disks instead then?

Yes.

Posted: **Wed Jun 25, 2025 6:41 pm**

Octocontrabass wrote: ↑Wed Jun 25, 2025 3:17 pm
AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 11:05 amI decided to turn off one of the configuration bits that enables the "spinup sequence" for the drive.
Setting that configuration bit disables the spinup sequence. It sounds like you were telling the WD1770 to read and write the disk without waiting for the drive to reach full speed!

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 12:03 pmChatGPT says
What's the point of asking fancy autocomplete if you don't know whether it gives you the right answer?

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 12:03 pmSD and DD were the same disks basically.
Do you confirm this?
There's no difference between SD and DD other than the data encoding. The disks are identical. The drives are identical.

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 12:03 pmI should really use DD disks instead then?
Yes.

On the datasheet it says that if the bit is 0, we enable the spin up sequence, and 1 disables it. I always had it as 0 for enabling it and that caused the corruption at the beginning of the track. Now is the datasheet wrong? Because after I disabled the spinup sequence, it worked.

It also seems that after I used DD disks, a lot of the corruption went away. So thank you so much for your advice on that. That made a lot of difference.

Posted: **Thu Jun 26, 2025 2:52 pm**

AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 6:41 pmNow is the datasheet wrong? Because after I disabled the spinup sequence, it worked.

As far as I can tell, the datasheet is correct. I would guess the problem is that your drive is very old and doesn't work correctly anymore. It's just coincidence that the problem goes away if you don't wait for the spindle motor to reach full speed.

Posted: **Thu Jun 26, 2025 3:21 pm**

Octocontrabass wrote: ↑Thu Jun 26, 2025 2:52 pm
AnalogChipDesigner wrote: ↑Wed Jun 25, 2025 6:41 pmNow is the datasheet wrong? Because after I disabled the spinup sequence, it worked.
As far as I can tell, the datasheet is correct. I would guess the problem is that your drive is very old and doesn't work correctly anymore. It's just coincidence that the problem goes away if you don't wait for the spindle motor to reach full speed.

All 3 drives that i tested behaving in the exact same way though?

Posted: **Thu Jun 26, 2025 3:28 pm**

AnalogChipDesigner wrote: ↑Thu Jun 26, 2025 3:21 pmAll 3 drives that i tested behaving in the exact same way though?

Well, I have no explanation for that! Do you have any way to measure how many index pulses occur between sending the command to the WD1770 and the first DRQ?

OSDev.org

Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...

Re: Problems formatting a 5.25" floppy...