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Re: ST512 [WAS:RE: Re: Nuking an MFM drive with a magnet, format/servo gone?]

by Tom Gardner

The ST512 was a thin-film head version of the ST506, per Seagate : "This increased capacity is accomplished by using the inner portion of the disc surface that was previously unused and by increasing the disc track density from 255 tracks per inch to 270 tracks per inch To reliably use the inner portion of the disc. The ST512 uses a new type of read/write head - a "thin film" head." It was dropped in 1981 due to the lack of a reliable supply of heads and replaced by the ST412. -----Original Message----- From: Tony Duell [mailto:ard.p850ug1@gmail.com] Sent: Friday, February 03, 2023 9:27 AM To: Alexandre Souza Cc: General Discussion: On-Topic and Off-Topic Posts Subject: [cctalk] Re: Nuking an MFM drive with a magnet, format/servo gone? On Fri, Feb 3, 2023 at 5:21 PM Alexandre Souza <alexandre.tabajara(a)gmail.com> wrote: > > I thoug the right one was st512...can you enlighten me on this subject Tony? I've never heard it called that. It's often called 'ST506' but that drive had a few differences from the later ones. it didn't support buffered seeks AFAIK. The ST412 did and was the most common of a family of 3 similar drives (ST406, ST412, ST419) so it tends to be used as the de-facto name of the interface. -tony

2 years, 5 months

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Formatting and using RQDX3's and 2190's.

by Chris Zach

Decided to spend some time working on my 11/73 with MFM drives. Currently it has one of my RQDX3 boards (I have 3, 1 in attic), a 40mb ST412 drive (the half height Seagate whatever) which works fine. No issues there. I'm trying to format an RD54 compatible drive and am running into major issues. First, my two RWDX3's have different ROM dates, the old one is 1986 and the new one is 1990. This is important because I can't boot RX33 disk images with my GoTek using the old card but I can using the new one. Question: I'm guessing the old ROMs only supported RX50 disks? Or is it a secret jumper setting. Anyway I do have both RX33 and RX50 versions of XXDP so not a big issue. On to formatting. The old controller (which I used for the 40mb Seagate) had pins 2-3 jumpered on W23. With that the RD54 was able to autoformat but then would crash xxdp as soon as the initial format was done. Odd. So I used the new controller with 1-2 and 3-4 jumpered. Same problem. Then I tried having 1-2 jumpered and did a manual format (not autoformat, select RD54, etc) I noticed that on the old board it would ask me for the date when doing this kind of format, on the new board it would just ask me for the serial number. Odd. Question: Is the ZRQCH0.BIN file calling different routines in the RQDX3 ROM? Anyway after this the drive would format but then do endless seek errors on the "read" portion of the disk check. Two drives did this, so it's probably not the drives. Odd. Putting the drives on the Dave Gesswin MFM reader showed all cylinders could be read. Question: Can Dave G's board be used to low level format an RD54? Can it test physical disk for errors (wasn't sure) Now the drives only format for a minute or two before throwing errors. Looks like something is very confused on XXDP. Not going to try any other disks until I figure this out. Thoughts? Different sites say different things about the RQDX3 jumpers, some say to jumper 2-3 to allow more than 7 heads, some say to jumper pins 1-2 and some say jumper pins 1-2 on "early ROM" and 1-2 3-4 on "later ROM". This is a serious pain, but just what settings should be done to allow low level formatting, and did my previous attempts to low level wedge these disks from the RQDX3 point of view? Can I do a low level wipe with Dave Gesswin's board/software? Thanks! Chris

2 years, 5 months

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ZFS, was [... GreaseWeazle ..]

by emanuel stiebler

On 2023-02-02 04:38, David Brownlee wrote: > That reminds me (looks at 43.5T of zfs pool that has not had a scrub > since 2021). > > It can be nice to have a filesystem which handles redundancy and also > the option to occasionally read all the data, check end to end > checksums (in the unlikely case a device returns a successful read > with bad data), and fixup everything. Does not eliminate the need for > remote copies, but gives a little extra confidence that the master > copy is still what it should be :) So, what else do you guys use, to make sure your data is safe for the years to come?

2 years, 5 months

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CD-R, DVD-R media available

by David Barto

100’s of CD-R, Sony, TDK, and FujiFilm. 25-30 DVD-R Sony and TDK And CD cases sufficient to hold all the disks Heavy, available for the cost of shipping. I’m in San Diego, so local delivery is possible. David

2 years, 5 months

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1975 Homebrew Computer Club Newsletter

by Tarek Hoteit

One website has an archive of the first Homebrew Computer Club newsletters. The newsletter is associated with the Homebrew club that kicked off the personal computer revolution https://arkive.net/gallery/homebrew-computer-club Regards, Tarek Hoteit

2 years, 5 months

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Computer Museum uses GreaseWeazle to help exonerate Maryland Man

by rar＠syssrc.com

Museum Staff Helps Exonerate David Veney January 19, 2023, Hunt Valley, MD — Staff members of the System Source Computer Museum recently completed a project that helped exonerate David Veney, wrongly convicted of rape in 1997. In 2005, after Mr. Veney sought a new trial, the state found irregularities in the prosecution, released Mr. Veney from prison, and declined to re-prosecute. Maryland is one of 35 states that provides compensation for wrongly incarcerated people. But quirks in the law kept the law from applying in Mr. Veney’s case. In 2021, the Maryland law was amended, making Mr. Veney eligible for partial compensation for the nearly nine years he spent in prison. Still, Mr. Veney had not been exonerated.. In June 2022, the Computer Museum at System Source in Hunt Valley, MD, was contacted by Patrick Gilbert, Senior Assistant States Attorney and Chief of the Prosecution Integrity Unit, who asked “Can you read data from a 5.25” Floppy Disk?” Bob Roswell, curator of the museum, quickly replied “Of course!” It wasn’t quite that simple. In theory, the diskette contained the court stenographic records from the 1992 rape trial of Grant Jones. The transcript was thought to contain evidence that would exonerate both Mr. Jones and Mr. Veney, but the printed transcripts from 1992 had been lost. Unfortunately, the diskette was neither IBM- nor Apple-compatible. It had been written on a DEC PDP-11 minicomputer using the RSX-11 Operating System. Although the museum has a PDP-11 in its collection, it had not yet been restored and could not be started. Brendan Becker, who runs the BLOOP museum inside the Computer Museum, jumped on the problem. Brendan set up a “Greaseweazle,” a device that reads the magnetic flux transitions on the floppy disk without regard to operating systems, disk formats, or errors. The process returned a file containing long binary strings of ones and zeros. Brendan was able to decode the file structure and found that disk (despite some unreadable parts) contained the raw keystrokes that the court stenographer had recorded in the 1992 rape case using a Stenograph machine from the era. An operator of a Stenograph machine uses chords to rapidly encode conversation by creating keystrokes to represent words, syllables, and phrases. While there is some standardization, each stenographer has his/her own “theory,” which results in individual styles for different stenographers. Luckily, Patrick Gilbert was able to obtain the services of the stenographer from the original trial (now retired). Together, they were able to substantially reconstruct the transcript from the 1992 trial, using the data provided by Brendan. The recovered transcript showed weird similarities to Mr. Veney’s case. On March 4, 1992, Alice Arroyo claimed to have been raped while walking home from volunteering at homeless shelter. In her account, the assailant grabbed her shirt, ripped it open, and scratched her chest with his nails in a long, vertical raking motion. Ms. Arroyo provided police with a detailed description of her assailant including the jacket he was wearing. The following day Grant Jones walked into the Salisbury Police Department (in Wicomico County, MD) to report that his wallet had gone missing from the homeless shelter. Mr. Jones matched the description of the assailant, was arrested, and was convicted of assault with intent to rape. On September 24, 1996, Salisbury Police responded to a complaint at the home of Alice Arroyo, who stated that she had been raped. Again, she provided a detailed description of the assailant and described suffering scratches on her chest in a long vertical raking motion. On October 3, 1996, David Veney, a former neighbor, was charged with rape. He was 20 years old at the time. Mr. Veney’s first trial in April 1997 ended in a mistrial. The hung jury consisted of four jurors voting to convict and eight declaring him innocent. In September 1997, Mr Veney was retried and found guilty of various charges, including burglary, assault, battery, and rape. He was sentenced to 25 years for rape and concurrent sentences for the other offenses. In 2005, Mr. Veney sought a new trial on the basis of ineffective representation. (That lawyer was later disbarred.) When the State reviewed the case, substantial doubts about Mr. Veney’s guilt arose, including the eerie similarity in Ms. Arroyo’s testimony in the two cases. Mr. Veney was released from prison, and the State declined to re-prosecute. The reconstructed transcript of Mr. Jones’ 1992 trial proved vital in establishing Mr. Veney’s innocence. On January 13, 2023, Judge Teresa Garland awarded Mr Veney approximately $730,000, along with medical, housing, and educational benefits. The staff of the Computer Museum at System Source is proud to have played a small part in Mr. Veney’s exoneration. Bob Roswell, Curator, later learned that the state had contacted numerous other technology firms, who were unable to render assistance, before asking the Museum for assistance. The Amendment to Maryland Law Regarding Compensation for Wrongful Convictions: https://mgaleg.maryland.gov/2021rs/Chapters_noln/CH_76_sb0014t.pdf Greaseweazle: https://decromancer.ca/greaseweazle/ Stenography Theories: https://www.artofchording.com/introduction/theories-and-dictionaries.html The System Source Computer Museum: Bob Roswell https://museum.syssrc.com/

2 years, 5 months

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Re: HP 41-CX

by David Brownlee

I had some idea of trying to get money for an HP 41-CX a while back, but on balance I think it's best to just go to someone who might be interested in fixing it up and valuing it for what it is. So - FTGH, just the cost of shipping (photo link below still valid) David On Sun, 19 Apr 2020 at 17:55, David Brownlee <abs(a)absd.org> wrote: > > I've come into possession of an HP 41-CX calculator - unfortunately it > appears to have had batteries left in it which have left corrosion on > the internal contacts. > > (some pics: https://photos.app.goo.gl/48bE7WJZP8R4PF9a9 ) > > My classic hardware tendencies tend to run more towards the "can run > *nix" end, and while I could just clean it up and throw it on eBay I > wondered if anyone here has a 41C shaped soft spot and would be > interested? (happy to trade/part trade for something they already have > for which they are less fond if that works :) > > David

2 years, 5 months

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PKBACK Floppies?

by Zane Healy

Some of the floppies I’m recovering data look to be either a multi-part ZIP file, or something. Was this a separate product from PKZIP? I’m not sure if I have a copy of PKZIP in the stuff I’ve recovered thus far. I’ve not pulled them into DOSBOX to try and restore them, so far I’ve just tried to use Stuffit-Expander. Part of the problem is every file has the same name, just on different floppies. Zane

2 years, 5 months

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Aging of unused CD-R media

by Zane Healy

I find myself wondering, how well does CD-R and DVD-R media that hasn’t been used age? I have quite a bit of unused Verbatim DataLifePlus, as well as some other media that’s unused. For the most part, I don’t need it, but I can see a couple reasons I might want to burn some in the future, mainly to exchange data with older systems. Zane

2 years, 5 months

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DLOAD BASIC command for Color Computer 1/2 heritage

by Jim Brain

Over at the CoCo Mailing List, there's a archeological discussion about the DLOAD BASIC command in older versions of the Color Computer BASIC. It uses the serial port (and no doubt was designed for computer sharing in classrooms or similar), but the questions are around how it was designed and what inspiration is drew from. I infer MS wrote the code, and the protocol includes: P.ACK - Acknowledge - C8 hex. P.ABRT - Abort - BC hex. P.BLKR - Block request - 97 hex. P.FILR - File request - 8A hex. P.NAK - Negative Acknowledge - DE hex. Does that look like any protocol anyone has seen before? Jim

2 years, 5 months

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