test-drb July 2006

test-drb@ccmp.vtda.org

204 participants
377 discussions

by trag＠io.com

>Date: Sun, 30 Jul 2006 19:07:00 -0400 >From: Dave McGuire <mcguire at neurotica.com> > >Tim Shoppa wrote: >> For me, far higher yield for double-sided PCB's >> comes from ordering boards over the >> internet. Generally you have to use (gasp!) a modern PC with >> Windows software, but other than that the experience is wonderful. > > GASP...I'm sorry to say this Tim, but this is SO untrue. The >majority of the Internet-based PCB fab houses accept Gerber-format >files...and while you *can* generate those with a legacy Windows PC, I >can't come up with any good reason why someone would want to. I do it >with Solaris on UltraSPARC all the time, for both commercial and hobby >projects. Commercial EDA software for modern platforms is hellatiously >expensive, but even that is unnecessary nowadays. I use two free >packages: gEDA for schematic capture and PCB for circuit board layout. >They also work nicely under MacOS X. I regularly do fine-pitch surface >mount designs with this software. For $200 one can get Osmond PCB for the Mac. It runs on 68K, PPC Classic, and OSX. Until earlier this year it was in beta and available free for testing. I completed two designs while Osmond was in beta which were exported to Gerber and sent out for production. It worked great. I'd do it again, but for my current designs, I just don't want to spend as much per board. Anyway, to avoid digressing too much, the point is, I agree. PCB design can be done affordably on platforms other than a Windows based machine. *Most* (virtually all) PCB fabs expect gerber files, not a proprietary file format generated by their in house software. However, perhaps what Tim meant is that to get some of the great deals available, one goes to the PCB fab which provides in-house software, and to run that software you need a reasonably up to date windows machine. This is certainly true for PCB Express or 4PCB or whatever they're called. Jeff Walther

17 years, 9 months

DEC Alpha equipment in DFW

by alexeyt＠freeshell.org

I'm reposting this with the permission of the author. Please contact cseiler at sdf.lonestar.org directly. === I've got a handful of DEC/Alpha equipment as part of an estate. I need to get rid of it, and I'd hate to see this stuff just get disposed of. I'd like to sell it cheap to an SDFer in the DFW area. Or anyone knows dealers in the area who work with this stuff and might be interested in buying, I'd appreciate a referral in their direction. First up is a DEC Digital VRCX1-WA 21-inch monitor. This is a great monitor. I'd even use it myself, but it's a huge CRT monitor that I just don't have the deskspace for. Manufactured 1997. Bought used in 2002 for $145. Works good. Would like to get $50 for it. Also have Digital Server 3000 50mhz Alpha 128MB. Unknown hard drive. He bought it with 4.5Gb SCSI, but I think he may have upgraded it. I don't know enough about the monitor this thing boots up into, but an Alpha person can contact me if they're interested and tell me how to figure it out, maybe. DEC Alphastation 400 4/233 with 256MB RAM. Have not even started this one up. DEC Personal Workstatioin 433au. Unknown RAM, appears to have no hard drive. HP SureStore DAT24 tape drive. I installed NetBSD on the Digital Server 3000 and got it to work just fine several months ago, but now can't remember how I did it. Need room, and don't have the time to fiddle anymore. The estate needs the money. So, if I could get $45 a piece for the computers and $50.00 for the monitor, I'd be really happy. It would be great if someone could take them all off my hands. I live in Denton, so I could meet someone halfway in Dallas, Ft Worth, or McKinney, etc. Money is not the huge priority, but I'd prefer not to have to ship them as it would involve a lot of boxing up and packaging and whatnot. So I'd rather sell them to someone in driving distance, even if it's for a small amount. The amounts aren't hard and fast, and I'd definitely consider a considerable discount if someone took it all of my hands in one batch.

17 years, 9 months

toner transfer circuit board etching

by wbblair3＠yahoo.com

> Message: 5 > Date: Sun, 30 Jul 2006 11:13:46 -0700 (PDT) > From: Chris M <chrism3667 at yahoo.com> > Subject: toner transfer circuit board etching > To: talk <cctalk at classiccmp.org> > Message-ID: <20060730181346.50833.qmail at web61021.mail.yahoo.com> > Content-Type: text/plain; charset=iso-8859-1 > > by any chance does anyone use this method, and would > be willing to small *even* number of sheets? The one > place I know of that sells it has a $50 minimum order > (Halted). Or maybe someone knows of a place with fewer restrictions. Here's an excellent news group that'll tell you everything you need to know about homebrew PCBs: http://groups.yahoo.com/group/Homebrew_PCBs/ It really is a fantastic resource on this topic because it has so many active members who are experts on the subject and highly experienced. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

17 years, 9 months

imsai 8080 power switch

by dgriffi＠cs.csubak.edu

If I'm reading things right, the Imsai 8080 directly switches AC power through the front panel power switch. Can someone suggest a relay circuit to remove the need to run so much power through the front panel? -- David Griffith dgriffi at cs.csubak.edu A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

17 years, 9 months

large data transfert (write) to SDRAM at fixed frequency

by pm.boyer＠wanadoo.fr

Hi ! I am new in electronic. I want to make an analog acquisition board with an ARM microcontroler ( Samsung S3C44B0x 66MHz) with a 8Mbytes SDRAM and an A/D converter( Analog AD775 ). The sampling rate of the A/D converter is at 30Mhz, and i would like to connect its digital output to the S3c44b0x data bus by using the DMA of the uC. Data sent by the ADC will be wrote to the SDRAM by using the DMA of uC. But the number of sampling can be very large, and the acquisition/transfert occur at a fixed rate (30 Mhz). The acquisition time and transfert to SDRAM can be more than 64ms (refresh time cycle of SDRAM). So, my question is : ?is the internal refresh cycle of SDRAM can disturb the data writing by the DMA to the SDRAM ? The ADC send data to the SDRAM through the DMA at a fixed rate during may be 1 or 2 second, and is this process can be stopped/disturbed by the internal refresh process of SDRAM ? If yes, is there a solution, to manage the two process ( fixed acquisition and SDRAM refresh cycle) ? Thank you very much. -- ------------------------------ M. BOYER Pierre-Marie Hameau de Biranques 34380 Notre Dame de Londres Tel : 04.67.55.09.17 ------------------------------

17 years, 9 months

large data transfert (write) to SDRAM at fixed frequency

by ajp166＠bellatlantic.net

> >Subject: Re: large data transfert (write) to SDRAM at fixed frequency > From: Pierre-Marie BOYER <pm.boyer at wanadoo.fr> > Date: Mon, 31 Jul 2006 14:45:27 +0200 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >Le Dimanche 30 Juillet 2006 18:19, jim stephens a ?crit?: >> Pierre-Marie BOYER wrote: >> >> >Hi ! >> > >> >The ADC send data to the SDRAM through the DMA at a fixed rate during >> >may be 1 or 2 second, and is this process >> >can be stopped/disturbed by the internal refresh process of SDRAM ? >> > >> >If yes, is there a solution, to manage the two process ( fixed >> >acquisition and SDRAM refresh cycle) ? >> > >> >Thank you very much. >> > >> > >> > >> If you are only collecting ADC data at that rate, can you use an I/O mapped >> device instead of DMA, and just poll and read the data? Or are you saying >> that the ADC data will start up and run at some rate approaching the memory >> cycle time for 1 to 2 seconds? >> > No, ADC data run at a fixed frequency (30 MHz) during several seconds, >so data, from the ADC, must be writen to the sdram at rate one byte every 0,03 usec, >during several seconds. >( ADC hasn't buffer). >But what happend when the SDRAM enter in its refresh cycle, which occurs every 64ms ? > >Tanks > >P.M.B. > Maybe this will help... Refresh is the periodic reading of all rows of a Dram. If you were to do a bulk write and the number of bytes written exceed the number of rows in the DRAM then refresh or not you will have refreshed the ram. Nominally refresh is handled in two ways bulk, doing all the rows in one long pass every so many mS as required by the devices. The better and more common technique is to interleave refresh in between accesses such that you will have accomplished refresh of all rows in the required time. My, $.02 is if your running an ADC at 30mhz and the system has SDRAM you still only using a fraction of the bandwidth and refresh is not an issue. Since your writing nearly (30mhz*2sec-60Mbytes) 60mbytes of data you will refresh the ram nearly 31.25 times in two seconds, likely more than enough to satisfy refresh. Allison

17 years, 9 months

Very strange Atari Printer

by bpope＠wordstock.com

> Whilst browing Yahoo! auctions, I came across this Atari 825 printer: > > http://auctions.yahoo.com/i:Atari%20825%20printer:5025875 > > Problem is, I can't figure out how it works. Where do you plug it in? > > :) Well, it does have gold umm... connectors so that has to be good! Cheers, Bryan

17 years, 9 months

Software needed for Nicolet FTIR

by dj.taylor＠starpower.net

Like the majority of you who participate here I love to tinker with old stuff. I have managed to buy a used Nicolet model 210 FTIR system complete with PCI interface card and cable. These instruments fascinate me because they depend on a combination of computers, electronics, optics, lasers and precision mechanical movement to perform their function. When I got it home it didn't work because the laser power supply was not getting the 12V needed to power it up, when I corrected that and plugged it back in the instrument went into a 'maintenance' type of mode with the moving mirror scanning in a free run mode. The internal infrared source appeared to be working also since it put out a soft orange glow. This instrument and the software for it are not supported by Nicolet - now Thermo Electron - because it is so old. It is from 1993, and I am looking for someone who has the G-Series bench driver and OMNIC version 6.0 or below. I'm asking the classicmp group for help since I think someone out there might help me along. When I spoke to the Nicolet rep he told me that he also had a machine at home [what a hobby!] so he could identify with me, however my machine was retired and I needed to get an old version of Omnic and the g-series bench driver, and it would have to run on Windows 98 or earlier, but Nicolet wouldn't sell it to me. So, if anyone out there knows of some laboratory/chemistry type who may have old versions of OMNIC laying around and no longer need them have them get in touch with me. Thanks Doug

17 years, 9 months

Mac 128K board

by wdonzelli＠gmail.com

Anyone here have a working Mac 128K motherboard available? I have an old machine here with some strange memory problems that I really do not want to invest any more time into. -- Will

17 years, 9 months

transcribing old docs

by dgriffi＠cs.csubak.edu

I'm transcribing the docs for a Radio Shack PT-210 printing terminal because I don't see it online anywhere and I just recently acquired a photocopy. This manual has a fair number of typos and a peculiar capitalization scheme which is typical of writing from the 1700s. Here's an example: [begin quote] If you set the PT-210 to Half Duplex and the Host is echoing the character, you will see two of each character on the Paper -- one character will be from the PT-210 and the other echoed from the Host. [end quote] So, is it a Good Idea to correct stuff like this? Should I be concerned about maintaining the page numbering? -- David Griffith dgriffi at cs.csubak.edu A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

17 years, 9 months

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test-drb July 2006