That was not a particulary strange format, I'd seen it on a Morrow system and the 765 even supported it. Here's an oddball. 28sectors by 128 bytes single density 8". Seems with minor programming differnces of the 1771 for smaller gaps you could end up with enough space at the end of a track for 2 more sectors or nearly 20k per disk. I had always found that 8" at 256k per side (128/26) single density was a good medium and for DD 512k per side and DDDS at 1mb was clean and easy to live with. The CP/M world had an oddity that people using it may have noticed. At 256k (241k useable) was near the minimum for not feeling terribly cramped. Smaller was painful and always needed more drives and once you hit 512k or bigger life got easier. I found that for 8" DSDD (1meg) and two drives was a good working environment for serious work. When I started with 5.25 floppies life got hard (80k perdisk!) and didn't improve till 320/360k (40track 2sDD). The prefered when I build a CP/M system with floppies these days is not less than 720/780k (either 3.5" or 96tpi 5.25 DSDD) or the minimum equivelent in semiconductor (eeprom,flash or battery backedRAM). Hope this sorta give a clue why people in the CP/M space tended to push for more space per disk. Keep in mind that hard disks and controllers were expensive even past the mid 80s. Allison