Search found 390 matches

by ZrX
Sun Jul 19, 2020 7:54 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

The tool is my experimental tool I use to manage and study odd disk formats. The FD1000 MFM manual states "The head address is in bits 1 through 4 and the cylinder address is in bits 9 through 15. Bits 5 through 8 are always zero." Yet the graph shows HEAD to use bits 0 through 4. But it doesn't spe...
by ZrX
Fri Jul 17, 2020 7:33 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

Ok this time the header shows the head/side flag changing between sides on every track. But the bit order of that value is weird, as in the byte value is 0 for first head and 8 for the second head. All the other header values are in a typical order. Also, in all the previous dumps the head value was...
by ZrX
Wed Jul 15, 2020 9:37 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

Can't remember if the Dbit FDADAP indicated at all on the display which side it's controlling.

Do reading both sides work on standard floppies with a normal 3.5" drive for example?
by ZrX
Wed Jul 15, 2020 8:08 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

Nice! The dump is moderately clean now. How did you get it working? The drive cable has four control signals that are used to select which of the four possible drives should listen to the command signals on the bus. Does the floppy have a label that really says DS or Double Sided? Or where is the in...
by ZrX
Mon Jul 13, 2020 6:57 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

Quite odd that the drive from the actual machine gives such noisy data. But looking at the flux times there's lots of shifting so perhaps the original hardware has a PLL that is able to compensate with all that and loads the disk just fine. Edit: You mentioned in the other post about the missing ter...
by ZrX
Sat Jul 11, 2020 9:30 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

After scratching my head quite a bit because something in the dump didn't add up with the FD1000 manual, then I realised the floppy is single sided. Some drives (like the Nec drive) just refuse to read 2nd side if the floppy itself is single sided. Others apparently ignore the head select signal in ...
by ZrX
Wed Jul 08, 2020 9:54 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

I have one of those NEC FD1165 drives myself. Requires just +5V and +24V to work. Interestingly they use the spindle with optical sensor to set the RPM, and mine spun at 720 RPM. Ended up buying another drive and while it was on its way I realised the sensor on the first one was just dirty. The seco...
by ZrX
Sat Jul 04, 2020 11:14 pm
Forum: Support
Topic: Texas DS990/1 Dump
Replies: 29
Views: 1082

Re: Texas DS990/1 Dump

The scatter plot of those dumps shows really bad noise. So bad that they're practically unreadable. Not sure if there's something wrong with the disks or if the drive heads are dirty. Also, manually decoding a sector from the mill-dump shows the format is non-standard such that DTC simply can't deco...
by ZrX
Mon Jun 08, 2020 5:08 pm
Forum: General
Topic: G64 Extended format
Replies: 8
Views: 2469

Re: G64 Extended format

Most likely (peeking into DTC): Format 0 - Unknown format 1 - GCR Data 2 - CBM DOS 3 - CBM DOS Extended 4 - MicroProse 5 - RapidLok 6 - Datasoft 7 - Vorpal 8 - V-MAX! 9 - Teque 10 - TDP 11 - Big Five 12 - OziSoft Extension 0 - Unknown protection 1 - Datasoft with Weak bits 2 - CBM DOS with Cyan load...
by ZrX
Mon Jun 08, 2020 4:40 pm
Forum: Support
Topic: Not working with one of my computers.
Replies: 6
Views: 311

Re: Not working with one of my computers.

Is it the same drive that writes ok on the other computer or are they two different drives?