test-drb March 2011

test-drb@ccmp.vtda.org

146 participants
225 discussions

by netsurfer_x1＠fastmailbox.net

Anyone here have the speech module for an IBM PC Convertible they want to get rid of? I just got one of these laptops & was hoping to score one. David M. Vohs Digital Archaeologist & Computer Historian Computer Collection: "Triumph": Commodore 64, 1802, 1541, Indus GT, FDD-1, GeoRAM 512, MPS-801. "Leela": Original Apple Macintosh, Imagewriter II. "Delorean": TI-99/4A, TI Speech Synthesizer. "Spectrum": Tandy Color Computer III. "Monolith": Apple Macintosh Portable. "Boombox": Sharp PC-7000. "Butterfly": Tandy 200, PDD-2. "Shapeshifter": Epson QX-10, Comrex HDD, Titan graphics/MS-DOS board. "Scout": Otrona Attache. (prospective) "Pioneer": Apple LISA II. "TMA-1": Atari Portfolio, Memory Expander + "Centaur": Commodore Amiga 2000. "Neon": Zenith Minisport.

13 years, 9 months

BIOS/Clock battery replacement

by Hollandia＠ccountry.net

One of my computers is a 486SX. The soldered-in battery is apparently failing; after a period of power-off, the time is badly off at re-start. The date and BIOS are so far unaffected. The motherboard has provision for an off-board battery. I am thinking of using a socketed CR2032 battery which I believe is rated at 3 volts. The manual for the computer describes the off-board battery as 3.6 volts. Is it asking for trouble to use a 3v rather than a 3.6v battery? If so, where are the 3.6v batteries available? Thanks, Kurt

13 years, 9 months

Who will be the last HD maker down the road?

by vintagecoder＠aol.com

> Date: Wed, 09 Mar 2011 12:06:10 -0800 > From: Al Kossow <aek at bitsavers.org> > Subject: Re: Who will be the last HD maker down the road? > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4D77DDB2.5030004 at bitsavers.org> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 3/9/11 11:46 AM, vintagecoder at aol.com wrote: > > > I don't know how that can be true. I can understand deleting doesn't > > work but is it true a simple dd if=/dev/zero of=/dev/sdx onto the flash > > card doesn't fill it with zeros? > > From reading the papers, there are many redundant cells, and the > controller between you and the flash is free to remap and lie about what > it has really done, including continuing to erase cells that have been > marked for garbage collection long after writing has stopped. I understand that and it makes sense "deleting" data or trying to overwrite a filesystem record doesn't necessarily do what we think. But filling the drive to its capacity with a utility like dd using zeros or random data has to work because you can read the data back, so it's really there. > This invalidates assumptions of repeatability of data recovery assumed for > forensic evidence. Interesting and I'm not sure I got what you mean. > Concern from the data security folks is what is really still there > on the parts if you go directly to the chips and bypass the controller. Right, for data that was "deleted", but new data that was written has to end up on the chip somewhere...and this means it really does replace what was there before, unless there's extra capacity there...in which case some number of passes of filling it with random data has to work eventually, by definition. Otherwise it's a bit bucket and not a storage device ;) > I'm concerned about the optimizations they mention in the controller > firmware geared to proprietary file systems (NTFS). What if these are > accidentally performed on some file system that ISN'T and NTFS file > structure? I saw a good piece on this point to the issue that most of the cards are optimized towards FAT32. It explained it may be harmful performance wise to other file systems that are based on spinning media and write small blocks, since the flash works best with much larger fixed blocks depending on manufacturer. I guess we will see some interesting file system development as people address these issues both from hardware and software angles.

13 years, 9 months

hardware multiply/divide functionality in CPUs

by jules.richardson99＠gmail.com

... or mid-late '70s and early '80s CPUs, to be more specific. Can anyone furnish me with a better knowledge as to which processors of that kind of time period had hardware multiplication and division support? http://en.wikipedia.org/wiki/Binary_multiplier mentions the 6809, but I'm curious as to which* others had such hardware features (and when they started moving from simple shift-add routines to more complex approaches which used more silicon - or did that not happen until much later in the 80s?) * mainframe, mini, micro; I'm not picky. I'm more interested in building up a picture of how widespread hardware support was, and the various approaches that designers used. cheers Jules

13 years, 9 months

Digital archiving tools

by tshoppa＠wmata.com

> OTOH I keep all of my images compressed, precisely because I want to know if any copy has been corrupted. Specifically I prefer bzip2 (even though a lot of my imaging activities from the 1990's, before I knew about bzip2, are squirreled away in zip files and I have not necessarily moved them to bzip2). If for some reason the only copy of a bz2 file became partially corrupted I could know which parts were good and which parts were bad: RECOVERING DATA FROM DAMAGED FILES bzip2 compresses files in blocks, usually 900kbytes long. Each block is handled independently. If a media or transmission error causes a multi-block .bz2 file to become damaged, it may be possible to recover data from the undamaged blocks in the file. The compressed representation of each block is delimited by a 48-bit pattern, which makes it possible to find the block boundaries with reasonable certainty. Each block also carries its own 32-bit CRC, so damaged blocks can be distinguished from undamaged ones. bzip2recover is a simple program whose purpose is to search for blocks in .bz2 files, and write each block out into its own .bz2 file. You can then use bzip2 -t to test the integrity of the resulting files, and decompress those which are undamaged.

13 years, 9 months

List issues

by a50mhzham＠gmail.com

Can someone please explain what the problem is with my posts? I mean technically, not in terms of relative value to the discussion. I am (I'm pretty sure) legitimately subscribed to the list. You can ask Al Kossow who I am. I believe I have been a subscriber since 2002, although I only have messages dating back to 2004 to prove it. I was formerly subscribed as tpeters at mixcom.com. That was email address from the late 1990's until it was lost when my ISP got out of the business. In December 2010 I re-subscribed as a50mhzham at gmail.com and this is the address cctalk is sending all posts to. Except mine. I have just logged in and checked my options. Apparently I'm set correctly (settings are all as I expect them to be) especially "Receive your own posts to the list? " which is set to "Yes." I find I can no longer post. I do not see my own posts. My last few messages about SA-801 floppy drives were accused of being spam, with some sort of trojan or virus attached. What's going on? Why, if I get the posts from everyone, do my own not appear? How is it that I can log into http://www.classiccmp.org/mailman/options/cctalk with no problem, and yet be unable to post? Please help. -Tom Peters 150 . [Language] Then there's the apocryphal statement attributed to Alexander Haig: "There isn't a word in the English language that can't be verbed." NEW: a50mhzham at gmail.com ? N9QQB (amateur radio) "HEY YOU" (loud shouting) ? Second Tops (Set Dancing) ? FIND ME ON FACEBOOK 43? 7' 17.2" N by 88? 6' 28.9" W ? Elevation 815' ? Grid Square EN53wc LAN/Telecom Analyst ? Open-source Dude ? Musician ? Registered Linux User 385531

13 years, 9 months

AlphaMicro 68000 system, eBay BIN $125, located in Turlock, CA

by wmaddox＠pacbell.net

I saw this on eBay. No connection with the seller. http://cgi.ebay.com/Vintage-Alpha-Micro-S-100-68000-Server-AM-1072-VCR-i-o-…

13 years, 9 months

Who will be the last HD maker down the road?

by vintagecoder＠aol.com

On Wed, 09 Mar 2011 15:30:30 -0600 cctalk-request at classiccmp.org wrote: > Message: 22 > Date: Wed, 09 Mar 2011 12:46:24 -0800 > From: Eric Smith <eric at brouhaha.com> > Subject: Re: Who will be the last HD maker down the road? > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4D77E720.3050100 at brouhaha.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Richard wrote: > > Flash memory is problematic for secure data. Basically, its nearly > > impossible to securely erase a file from flash based disks. > > vintagecoder at aol.com wrote: > > I don't know how that can be true. I can understand deleting doesn't > > work but is it true a simple dd if=/dev/zero of=/dev/sdx onto the > > flash card doesn't fill it with zeros? > > That's *exactly* the problem. It doesn't. dd only fills the blocks > that are currently in use, but the card may have spared out marginal > blocks that still contain residual user data. Then I would think a few passes of filling it with random data should work. > This is true of modern hard drives as well. I like flash because you can snap them in pieces easily ;) All the theory comes to an end at my pair of vice grips! > > That's why the "secure erase" commands were added to the ATA command > set, and the drive is supposed to erase even the spared blocks. I don't trust that to work. But I do trust my vice grips.

13 years, 9 months

Who will be the last HD maker down the road?

by vintagecoder＠aol.com

On Wed, 09 Mar 2011 23:37:13 -0600 cctalk-request at classiccmp.org wrote: > Message: 6 > Date: Wed, 9 Mar 2011 13:39:02 -0800 > From: Christian Kennedy <chris at mainecoon.com> > Subject: Re: Who will be the last HD maker down the road? > To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org> > Message-ID: <77B95B40-4467-469B-B8EB-203C21DEAE3D at mainecoon.com> > Content-Type: text/plain; charset=us-ascii > > > On Mar 9, 2011, at 12:46 PM, Eric Smith wrote: > > > That's why the "secure erase" commands were added to the ATA command > > set, and the drive is supposed to erase even the spared blocks. > > Sandforce takes this one step further in that their SSD drives have AES > encryption turned on by default. If you issue a ATA secure delete to the > drive the key is wiped and regenerated, rendering all of the data in > flash, both primary and spare, into garbage. That's a good theory, but you have no way of knowing whether there's key escrow or not. The safest thing is to use your own encryption, then you know the key will not wind up on the drive somewhere. That's pretty easy to do on Windows or Linux these days.

13 years, 9 months

Who will be the last HD maker down the road?

by teoz＠neo.rr.com

No Idea who invented the hard drive (IBM maybe?) but Hitachi is selling out its division to WD who will now be number one in the market beating out Seagate. http://www.computerworld.com/s/article/9213599/Western_Digital_to_buy_Hitac… My stock of HDs has plenty of names that no longer exist (Fujitsu, Maxtor, Connor, Micropolis, Quantum, and maybe a JPS drive). I am sure there are dozens of companies that died before my collecting interest. I wonder if WD will be the last company standing making spinning disks before SSD takes over all markets.

13 years, 9 months

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test-drb March 2011