You are not logged in  CSDb User Forums Forums > C64 Coding > 1541 datarate 2012-05-15 01:16 Repose Account closed Registered: Oct 2010 Posts: 140 1541 datarate Hi I need help to understand the very low level 1541 disk format. From http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/15.. I see that Y1, the system clock (which I'm guessing is 16MHz, cause a clock part is listed in the 1541-II service manual), goes to a /2 and /8 divider, configured in cascade, which means 1MHz is output. What I need to know is the actual bitrate of the outer zone. Inside c= dos says the divisor is set to /13 to /16, is this from 1MHz? Also the wikipedia article on 1541 lists bitrates of 16MHz/4/13=307KHz. It's easy to answer, if you've written a fast loader, how long do bytes pass bye (GCR bytes)? If it's right, 13*8/4=26 cycles per byte in track 1. also do you know which bit is written first to the disk? lsb or msb? 2012-05-15 08:04 j0x Registered: Mar 2004 Posts: 213 Yes, the 1541 uses 26, 28, 30 or 32 (1MHz) cycles per byte when writing, depending on speed zone. The VIA's shift register is msb-first (left-shifting), as far as I know. 2012-05-15 18:55 tlr Registered: Sep 2003 Posts: 1535 See also here: Drive coding: safe maximum time between $1c01 reads? and here: Job codes'n buffers Refresh Subscribe to this thread: You need to be logged in to post in the forum. Search the forum: Search  All forums C64 CodingC64 ComposingC64 PixelingC64 ProductionsCSDb Bug ReportsCSDb DiscussionsCSDb EntriesCSDb FeedbackCSDb InfoCSDb moderatorsCSDb QuestionsCSDb V2 developmentMessages to moderatorsRequests  for   in Writer & textTextWriter  All times are CET. Search CSDb All Releases Groups Sceners Events BBS SIDs ------- Forum Comments Advanced Users Online Mike rytone/Onslaught zzarko Sentinel/Excess Menace/Spaceballs CreaMD/React iAN CooG/HVSC Linus/MSL^OXY^Fossil Core/VPN Guests online: 53 Top Demos 1 Edge of Disgrace  (9.6) 2 Coma Light 13  (9.6) 3 Bromance  (9.6) 4 Uncensored  (9.6) 5 Memento Mori  (9.5) 6 Comaland 100%  (9.5) 7 Unboxed  (9.5) 8 Lunatico  (9.5) 9 Wonderland XII  (9.5) 10 Christmas Megademo  (9.5) Top onefile Demos 1 Copper Booze  (9.6) 2 Daah, Those Acid Pil..  (9.5) 3 Dawnfall V1.1  (9.5) 4 Cityscape 2730  (9.5) 5 To Norah  (9.5) 6 Lovecats  (9.5) 7 Elite Code Mechanics  (9.4) 8 Barry Boomer - Trapp..  (9.4) 9 Offering  (9.4) 10 Tribute to Ben - Las..  (9.4) Top Groups 1 Booze Design  (9.4) 2 Performers  (9.4) 3 Oxyron  (9.3) 4 Fossil  (9.3) 5 Crest  (9.2) Top Cover Designers 1 Duce  (9.8) 2 The Elegance  (9.7) 3 Electric  (9.7) 4 Junkie  (9.5) 5 Mermaid  (9.3)

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