test-drb November 2011

test-drb@ccmp.vtda.org

178 participants
177 discussions

KryoFlux - imaging of vintage floppy disks via USB

by cb＠kryoflux.com

> I may be dense today, but after digging through the kryoflux.org site I'm > not having any luck finding the schematic. Don't be shy, download the software (Win32/64 is latest). It's free, no registration required, and schematics are included. Cheers!

13 years, 1 month

KryoFlux - imaging of vintage floppy disks via USB

by cb＠kryoflux.com

> Being a hardware geek myself, are current schematics available for the > kryoflux? I had asked a year or so ago and got pointed to old schematics > that were a couple revisions out of date. Just download the latest software package, it has the schematics included. Enjoy. Cheers, Chris

13 years, 1 month

Market value of VAX 4000-96 - Re: Can anyone explain this to me ?

by mcguire＠neurotica.com

Heh. OpenBSD's original claim to fame was that it provided a certain arrogant ass with a way to thumb his nose at his peers. I'm glad enough grownups eventually joined in to make it a useful project. -Dave -- Dave McGuire New Kensington, PA leaknoil <leaknoil at gmail.com> wrote: >On 11/4/2011 7:33 PM, Mouse wrote: >>> What would you do to a current Debian distro to make it more secure ? >> Boot the NetBSD install CD. >We are heading into platform war territory here but, shouldn't that be >OpenBSD ? Security was their claim to fame over NetBSD. Still it >wouldn't be any more secure than a current linux install. I think we are >talking about things as they were ten years ago. Today most OS are >really pretty tight out of the box. Much more so then they were in 1988 >or 2010 for that matter.

13 years, 1 month

Multiplexing was Re: Information on the PPS-4/1 4 bit microprocessor wanted

by benjamin.soelberg＠gmail.com

2011/10/31 Eric Smith <eric at brouhaha.com> > Benjamin S?lberg wrote: > > So if you multiplex 8 leds you need 8 times the peak current to keep the > > same luminance ? > > 8:1 multiplex requires 8 times the peak current to get the same average > power. Years ago I saw some claims that with multiplexing you can use > lower average power for the same perceptual brightness, due to retinal > persistence. However, I've seen other people claim that this is not true. > It would be entertaining to set up a double-blind test and find out. > > I would expect a double-blind person would say that he couldn't see any difference :-) Joke-a-side.. If multiplexing really did save power then just pulsing a single led would do the same.. It might be true... think bicycle lights ? -- Med venlig hilsen / Best regards Benjamin S?lberg

13 years, 1 month

KryoFlux - imaging of vintage floppy disks via USB

by cb＠kryoflux.com

On 4 Nov 2011 at 0:26, Chuck Guzis wrote: >>/Not only does it support raw imaging of flux transitions, we also / >>/support output of sector image formats for pretty much all major home />>/platforms of the last 25 odd years (as well as a few strange ones). / >That's a pretty bold claim. I'm not saying that you haven't, just >that I've got several cabinets full of samples and some are very odd >indeed. >Suppose I were to send you a specimen copy of one without providing >any details (pretty much what I'm given to work with). Do you think >you could send me a duplicate and a sector-by-sector dump? > >I'd really be impressed. Chuck, how about the following: You just try this for yourself; it already supports so many generic FM and MFM formats, chances are, a broad range will work out of the box. My offer would be as follows: I send you a board, you give it a try with your various test disks. If your data does not read as expected, or there is something we don't support yet, but should be supporting, you make a STREAM dump and put it on our FTP. We'll take a look. I'd have to ask for a EUR 50.- deposit, which I will gladly refund the moment you send it back (are 60 days long enough to give it a try?). I am not asking you to sign anything and it does not come with any obligations. Plus: If you'd want to keep it, you keep it for EUR 50.-. Your only risk would be the return postage... And I'd of course like to hear all feedback you have, even if negative, here on the list. What do you think? --Chris

13 years, 1 month

Post Jobs speculation or just scrap thieves?

by jbdigriz＠dragonsweb.org

Had a IIe, a gs, and several Mac SEs and SE 30s take missing this past weekend, along with some empty filing cabinets and a pedestal for a TI DS-10 drive. DS-50 disappeared a while back. Anyone else having a problem? jbdigriz

13 years, 1 month

Encompass US down?

by fraveydank＠gmail.com

I figured it was about time I gave VMS a shot, but to get a hobbyist license I need to join Encompass US. encompassus.org seems to be down in a not-so-good way. Anyone have any insight on that? - Dave

13 years, 1 month

SWTPC Progress...

by wh.sudbrink＠verizon.net

Hi, Some time ago, I asked for some help locating documents for the Percom LFD-400 disk system. A number of people kindly helped out so I thought I would give a brief progress report to the list. 1) I removed various hacks on the MP-C and MP-S boards to return them to "factory" spec. 2) I implemented a switch on the MP-A CPU board to turn the onboard RAM on and off. This made debugging much easier. At this point, I was able to boot into SWTBUG with the MP-A RAM turned on. 3) I debugged several problems with the GIMIX 16K static RAM board. The original owner reported that this card always caused problems. No schematics seem to be available for it so the troubleshooting was slow going. The most interesting problem was that one of the 5 volt regulators (there are 4 on the board) was only providing 1.8 volts. As well as powering one of the 4K banks, this regulator was supplying power to some of the address decoding chips. With the out of spec supply, these chips were interfering with the correct operation of the address bus, preventing the whole system from operating. Other problems included some dead RAM chips, some bent pins on socketed chips and 39 undocumented dip switches. If somebody turns them up, I would love to get the docs for this board. At present, I have determined that 16 of the switches control the address of the 4 4K banks of RAM. I have left the other 23 switches as they were set when I acquired the system. Experiments as simple as turning them all on or off result in a non- functioning system. 4) I implemented the MP-B motherboard enhancement documented in the September 1978 issue of Interface Age. Fortunately, my MP-B was built with sockets, so the modifications can be easily removed if it should be necessary to restore the system to "factory" behavior. 5) I tied the MP-B mod into the address decoding on the 32K GIMIX card and the system now has 48K less 32 bytes of RAM and boots into SWTBUG with the MP-A RAM turned off. 6) I then proceeded to the Percom floppy interface board and determined to my great pleasure that it was functioning perfectly. I was able to jump into MINI-DOS+ with the SWTBUG 'Z' command, format a disk and create some files. I did this initially with a different 5 1/4 inch floppy drive as the original Percom (Shugart) drive had some problems. 7) I corrected two issues with the Percom drive and it now functions correctly. The first issue was shorted caps on the logic board. These were easily identified as they were smoking. The second problem puzzled me for a while. The drive worked fine as long as I did not put the cover on it. MINI-DOS is, unfortunately, pretty cryptic with its error reporting, only giving integer error codes. The magazine articles that I got don't document them. I finally figured out the problem when I noticed that the drive stopped working when I leaned over it. Turned out that there was some dust partially obscuring the index sensor. With the lid off and the overhead light shining on the drive, there was enough index signal for the drive to work. Put the cover on, or even shade the drive, and the internal LED was not producing enough light to detect the index holes. Interestingly, canned air was not enough to dislodge the dust. I had to reach in with a small, soft, unused paint brush and poke around to get it to the state where it works reliably with the cover on. One neat thing about the drive is that it has two sets of index and write-protect sensors. It is "flippy". It only has one read/write head, but you can insert a double sided diskette in either side up and use both sides. So, now I need some software. For those visually inclined, I put some pictures here: http://wsudbrink.dyndns.org:8080/swtpc6800/ Pictures 1 to 11 are of the AC-30 cassette interface and CT-64 terminal that I will be working on next. Pictures 16 and 17 are of the 6800 cover (I'm missing the screws). Pictures 18 to 21 show the output and listing of an SWTPC BASIC program I wrote to solve last week's Car Talk puzzler. Pictures 22 to 25 show SWTBUG working and using both serial interfaces. Pictures 27 and 28 show booting from SWTBUG into MINI-DOS+, getting a file listing and loading BASIC from a diskette. Pictures 30 to 35 show the beast itself. The cards from front to back are 1) The GIMIX 32K RAM 2) The GIMIX 16K RAM 3) The Percom floppy interface 4) The SWTPC MP-A CPU 5) The I/O card to the left (slot 0) is the MP-C and the card to the right (slot 1) is the MP-S. Picture 34 also shows the Percom floppy drive. Picture 35 is from the back. You can see the switch to control the MP-A RAM and also the small brown card that is the MP-B addressing enhancement. Bill

13 years, 1 month

another weird pdp 11/70 color scheme

by michael.99.thompson＠gmail.com

> From:?David Griffith <dgriffi at cs.csubak.edu> > > Here's a variation of the pdp 11/70 with a chocolate-brown and white color scheme: ?http://661.org/images/csis1170.jpg > > -- > David Griffith > dgriffi at cs.csubak.edu The Rhode Island Computer Museum has two 11/70 panels from CSI. The CSI systems ran a regional newspaper. -- Michael Thompson

13 years, 1 month

Reading obsolete ICs... Mostek 3851 PSU

by pinball＠telus.net

Has anyone tried to read the data from the Mostek 3851 PSU (ROM, I/O) used with the 3850? I am looking to replace these tiny computers with a modern FPGA or similar... Thanks, John :-#)#

13 years, 1 month

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test-drb November 2011