xerox 19790124 Notetaker Disk Capacity free download

File name 19790124_Notetaker_Disk_Capacity.pdf

Inter-Office Meulorandum To LRG, Doug Fairbairn Dat~ January 24, 1979 Frem Larry Tesler Location Palo Alto Subject Notetaker Disk Capacity Organization PARC/SSL XEROX Filed on: disk-capacity.memo The capacity of the Notetaker floppy disk has been advertised as 340,000 bytes. That quantity assumed double-density, dual sided-disks, and a particular format. rn1is memo summarizes some possibilities for formatting single-sided disks. Standard IBM -style fonnats have an overhead in address marks and synch marks equivalent to 60 or more bytes per track plus 50 or more bytes per sector. rIlle WD 1791 can handle non-standard formats, but below certain unknown minimum values for the synch mark overhead, reliability will be sacrificed. Nominal disk capacity (according to Shugart literature): Single density: 110K Double density: 220K File Format (128 byte sectors, IBM style): Single density: 35 tracks * 16 sectors * 128 bytes = 71,680 [35*(60+-16*(60+ 128