Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!decwrl!shlump.dec.com!decuac!c3pe!charles From: charles@c3pe.UUCP (Charles Green) Newsgroups: comp.sys.atari.8bit Subject: Re: Need Sector Editor! Message-ID: <7312@c3pe.UUCP> Date: 29 Jun 89 03:16:19 GMT References: <9624@boulder.Colorado.EDU> <41834@bbn.COM> Reply-To: charles@c3pe.UUCP (Charles Green) Organization: C3 Incorporated, Herndon, VA Lines: 39 In article <41834@bbn.COM> you write: >I was thinking that a cassette might be a great way to make backups. groan... at least, my 1010 is *very* unreliable. >How much data does like a C-90 hold? Does ARC/UNARC do tapes? Or should >I just go ahead and write a backup program? If I hadn't gotton a second >disk drive I would have done this ages ago anyway. Um, 600 bits per second / 10 bits per byte = 60 bytes per second. 60 bytes/sec * 60 sec/min * 90 min/cas = a whopping 324 Kbytes *unformatted* storage per C-90. But using the C: device puts a monstrous interrecord gap on the tape [grab Tech Ref notes, flip, flip, page 74] of 3 seconds versus [ f FLOAT 9 1 2 8 ENTER 6 0 / ] a little more than two seconds of meaningful data. Ouch - that means about 134 K bytes. A single-density floppy gives you 90K less a few of the 40 tracks, enhanced-density (1050) 130K bytes, and double density 180 bytes - double these numbers if you flip your floppies. Now compare the cost of the cassettes and floppies per Megabyte... Better to use the Vaporware Industries "RS232 cassette", which hooks up to your existing stereo cassette deck to read and write data eight times as fast (4800 bps), using the phase-coherent FSK generated by the XR2206 chip, and demodulated with the XR2211. Since you now have access to twice as many tracks on the cassette (left and right in each direction), this works out to a whopping 5 Megabytes of unformatted storage. And with the optional "Pie in the Sky" (PITS) backup software, using Hamming error-correction code on 8Kbyte blocks, you only lose 20% to overhead, yielding you four 1Mb tracks on a C-90. The glossy says it uses the same frequencies as the old 1200bps voice-grade FSK modems, only multiplied by four because the 300-3300Hz telephone channel has one-fourth the bandwidth of the typical cassette deck, so it's certainly within the realm of available technology. Let's see, where *did* I put that literature... -- {decuac.dec.com,cucstud,sundc}!c3pe!charles ex::!echo Boo: