Mastodawn

Disk Blitz Feb 28, 2023

@douglasvb @savetz it will happily image Kaypro disks, including the funky ones where both sides of the disk report as being side 0. It won’t currently let you extract files from CP/M disks, but you can use the images with emulators or other tools that handle files.

Disk Blitz Feb 28, 2023

Kay Savetz Feb 23, 2023

John Morris' amazing Applesauce floppy disk controller just recovered one of the very first computer programs I ever wrote, from a very old floppy disk. I'm over the moon to see this running!

I've digitized thousands of floppy disks using Applesauce, but am especially grateful for this one.

Show thread

Disk Blitz Feb 28, 2023

@a2_4am If I had time to write up more documentation for Applesauce, you would know that you can also use a tilde in the search string. "D5AA96~BBF9" searches for a synced D5AA96 (prologue) which is followed by a BBF9 (that is allowed to be desynchronized). It narrows the results down to a single instance on the disk.

Show thread

Disk Blitz Feb 13, 2023

@philpem I have quite a few of them. Fairly common from when single sided drives were king.

Show thread

Disk Blitz Feb 8, 2023

@ApplesauceFluxes @Ange with the black outer tracks and bright white for the others, I would guess that this was a PC disk (MFM-encoded) that was imaged in a Disk II drive at quarter track resolution. The black tracks are due to the head offset for the seconds side, and the bright white is because the flux density is high higher than expected. And imaged using client software that is at least a couple years old.

Disk Blitz Jan 22, 2023

I have re-opened the Applesauce store after an extended holiday break. Apple 3.5 Sync Sensors are back in stock. And there is a new Naked Mac Drive Adapter (very limited supply) that allows you to connect bare 800K and SuperDrives directly to Applesauce without needing the A9M0106 enclosure. https://applesaucefdc.com/order/

Applesauce Order Form – applesauce

Show thread

Disk Blitz Dec 18, 2022

@crazyc Yup, a WD1797 I believe.

Show thread

Disk Blitz Dec 18, 2022

For folks that like pics, here is the magic Nabu PC sequence that allows it to recognize its own disks. See the thread for more details.

Show thread

Disk Blitz Dec 18, 2022

Well, we now know what it takes to makes real working Nabu PC disks. But it also leads us to a few problems. There are no current sector-based disk image formats that can properly contain these disks as none of them can deal with the special sequence. All of the current IMD files done with ImageDisk that were thought to be good images are actually missing the sequence because the tool never knew to even look for it. Although I can likely add support for generating the needed sequence for these disk when writing. We currently are going to need to be flux imaging these disks only. And there are a limited set of tools that can handle reading and writing the disks.

Show thread

Disk Blitz Dec 18, 2022

Turns out that it isn’t a key to unlock a DPB. It actually is a complete DPB. It is laid out like this:

A1 A1 <4e x 12> <4 bytes that are maybe volume/disk id> 00 <DPB>

And it translates to:

spt = 40 ;Number of 128-byte records per track
bsh = 3 ;Block shift. 3 => 1k, 4 => 2k, 5 => 4k....
blm = 7 ;Block mask. 7 => 1k, 0Fh => 2k, 1Fh => 4k...
exm = 0 ;Extent mask, see later
dsm = 194 ;(no. of blocks on the disc)-1
drm = 95 ;(no. of directory entries)-1
al0 = 224 ;Directory allocation bitmap, first byte
al1 = 0 ;Directory allocation bitmap, second byte
cks = 1800h ;Checksum vector size, 0 or 8000h for a fixed disc.
off = 1 ;Offset, number of reserved tracks
psh = 3 ;Physical sector shift, 0 => 128-byte sectors
phm = 7 ;Physical sector mask, 0 => 128-byte sectors

If you don’t know what any of that means, then just trust me that it matches how the disk structure is organized.

Ok, so what now?