test-drb February 2014

test-drb@ccmp.vtda.org

191 participants
208 discussions

Fw: Victor Poor/Datapoint 2200 videos/audio

by tom_a_sparks＠yahoo.com.au

> > I am looking for video/audio on Victor poor and/or Datapoint 2200 for a class > assignment > > > > > --- > tom_a_sparks "It's a nerdy thing I like to do" > Child of the Internet born 1983 > PGP ID: A7EF6006 > Please use ISO approved file formats excluding Office Open XML - > http://www.gnu.org/philosophy/no-word-attachments.html > Ubuntu wiki page https://wiki.ubuntu.com/tomsparks >

10 years, 10 months

Chicken-and-egg problem with NEC PowerMate SX Plus

by jpw＠coherent-logic.com

Hello all, I recently picked up an NEC PowerMate SX Plus from eBay. Have been looking for one for years, so I jumped at the opportunity. The machine has no hard drive at all, and 5.25" (1.2MB) and 3.5" (1.44MB) floppy drives, configured as drives A and B, respectively, connected to an ISA FDC that also includes an IDE controller. Bought an IDE-to-SD board and a 256MB SD card to use as a hard drive. The difficulty is that this is one of those wonky beasts from the very late 1980s that requires a DOS-based utility in order to access the BIOS settings, which I must do in order to configure the cylinders/heads/sectors for the SD card. I have downloaded all of the PowerMate utilities from NEC's FTP site, per this thread: http://www.vintage-computer.com/vcforum/showthread.php?26016-NEC-Powermate-…, but this machine can only boot from the 5.25" drive. I have plenty of DSHD 5.25" media (brand new) upon which to write an MS-DOS boot floppy, but the only other machine I have whose BIOS claims to support 5.25" drives will neither read nor write 5.25" media in any of the three drives I've tried, claiming that track 0 is bad, or giving me a general failure error. Swapping the 5.25" and 3.5" drives in the NEC is out, since I would again need to get to the BIOS settings in order to make it all work. Not having the budget at the moment in order to buy more machines, I'm wondering if any of the people on this list have any suggestions, or would perhaps be willing to write such a boot floppy for me, if compensated for shipping and cost of media. Thanks in advance, JPW

10 years, 10 months

AT&T UNIX PC - default interrupt/break key

by classiccmp＠philpem.me.uk

Does anyone know what the default BREAK/Interrupt key combination is on the AT&T 3B1 / 7300 UNIX PC? I was expecting Ctrl-C, but that doesn't seem to do anything. (I'm trying to kill off a long-running task which I've lost patience in ever completing!) Thanks, -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/

10 years, 10 months

beware of "andananautions"

by js＠cimmeri.com

Unfortunate that the seller would jump to a cancellation so quickly, but sellers are only obligated to abide by the terms of their ad, and of course, ebay's policies. They are not obligated to do combined shipment. You can ask for combined if a combined policy is not stated in the ad, but be willing to accept a "no." I've had many sellers never answer my own requests for combined, so after waiting a few days for a reply, I just went ahead and paid "as purchased." The seller in question is just on of those overly anal a-holes one encounters on ebay every so often... but it is within his rights to insist upon "pay as invoiced." - jWs On 2/2/14 6:47 PM, cctalk-request at classiccmp.org wrote: > Subject: > beware of "andananautions" > From: > Al Kossow <aek at bitsavers.org> > Date: > 2/2/14 1:40 PM > > To: > General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > > > wow > > won some manuals cheap, then sent a message to see if they would > combine shipping. > > the seller canceled all of the auctions, and apparently there is no > recourse from the buyer. > > read his reply for yourself. > > this is the first time in 5000+ ebay deals that someone backed out > after asking for combined shipping. > > beware.. > > his 'justification' > > Dear al_kossow, > > 1. You won several items yesterday. > 2. I sent you an invoice for the total amount. > 3. You emailed your disagreement over the terms of your purchase. > 4. Therefore, we do not agree over the terms of the transaction. > 4. So I filed the appropriate request to cancel the transaction with > ebay. > > Now, you have suddenly changed your mind and claim that your purchase > was a "Binding Contract"? > Sounds like you want your cake and eat it, too. > First, you engage in feedback extortion to try coerce me to lower the > purchase price. > Then, when you did not get your way, you attempt to compel me to go > through with the transaction. > > Unfortunately, when you expressed your disagreement over the terms of > the sale, it was obvious that there was no meeting of the minds in > this transaction. As such, there is no contract. We both agreed to > cancel the transaction and that is ok. I am sorry you were > disappointed in the terms. I have refunded your paypal payment. You > are whole. > > I am just curious as to where else you can buy something and then > negotiate the terms of the transaction. > After you have filled up your gas tank, do you then ask the gas > station for a discount? > >

10 years, 10 months

Happy 30th MacIntosh

by c.murray.mccullough＠gmail.com

I look back with great fondness in regards to the original MacIntosh. It was 'ahead' of its time. Great marketing didn't hinder it either! Murray :)

10 years, 10 months

Who built the first minicomputers?

by steve＠tronola.com

Think DEC built the first minis? Not so fast... I'm pleased to announce that we have just published a new, carefully researched article on Tronola.com which explores this very question: http://tronola.com/html/who_built_the_first_minicomput.html Enjoy! Steve Lafferty http://www.tronola.com

10 years, 10 months

Datapoint 2200 cassette unit wanted...

by jdr_use＠bluewin.ch

To complete the Datapoint 2200 i received today I would love to have the cassette unit. ( my system has 4 x 8" SS floppies, but no cassette unit ) I know, chances are low, but if you don't try... I'll start however, by tackling the extreme screen rot.

10 years, 10 months

Jason Ranheim Scanned Documents

by n2dvm＠arrl.net

I'm looking for ANY and ALL clean & clear scanned Jason Ranheim Cartridge documents and code/software etc.. I've found documents for the PCC-4 and PCC-8 carts but the scan is crappy and hard to read, mostly in the example code sections. Any help would be great. --- WWW: http://www.commodoredungeon.com QUOTE : "A Clean bench is a sign of a weak mind."

10 years, 10 months

The Typography of /2001/

by lproven＠gmail.com

Wonderfully obsessive, but also looks in some detail at the real and fake tech used in the great film. But the author cannot identify the numeral in some screenshots. I wonder if any CCtalkers can? http://typesetinthefuture.com/2001-a-space-odyssey/ -- Liam Proven * Profile: http://lproven.livejournal.com/profile Email: lproven at cix.co.uk * GMail/G+/Twitter/Flickr/Facebook: lproven MSN: lproven at hotmail.com * Skype/AIM/Yahoo/LinkedIn: liamproven Tel: +44 20-8685-0498 * Cell: +44 7939-087884

10 years, 10 months

DEC Transistor Substitution

by steve＠tronola.com

Hi Michael, At 05:37 PM 2/1/2014, you wrote: >The PDP-9 at the RICM uses a bunch of B602 Pulse Amplifiers...The transistors are >listed in the Schematic as DEC-6A and DEC-6B. The parts are marked >DEC-2894-3A and DEC-2894-2B. > >Can I substitute 2N2894 parts for these transistors? --- The datasheet I found for the 2N2894 shows breakdown voltage at 12V. The B602 operates on supplies of +10V and -15V. While I didn't immediately find a schematic of the B602, I did find the B360, which seems similar except that a delay line is included. It isn't obvious to me, whether or not the PNP devices see more than the 15V that a simple inverter circuit would. If it were just 15V, the chances are good that the 2N2894 would work, because actual breakdown would be much higher than the 12V minimum spec. You can easily test the breakdown voltage of a sample (non-destructively) by applying it through a (say) 1K resistor to the collector and emitter, with the base open, while monitoring the voltage across the resistor. Raising the voltage, the point at which you see perhaps 1V or so could be considered the breakdown (BVceo). [The datasheet uses a much higher current but I would be more conservative.] If you see almost nil at 25-30V, the device should work okay. If it's 15-20V, it depends on the circuit as mentioned above. DEC part substitutions at http://so-much-stuff.com/pdp8/repair/subst.php showed a large number of entries but DEC-6 was given as "NONE". Looking at the turn-on, turn-off times for the 2N2894, I see max figures of 60, 90ns. From the 10MHz ratings of the B-series modules and the mention of a typical 40ns input pulse, those figures don't give me a warm feeling. On the other hand, speed is very dependent on drive, so actual performance could be much faster. Also, looking at a more detailed datasheet, showing curves of actual timings, I see that operating around 10mA, switching is in the 20-30ns region. You could setup a working module with a 40ns drive pulse, while observing input and output on a 2-channel scope. Measure the delays of both initial and trailing edges. Then observe the module with the substituted devices and see if there is a significant difference. Casting about at Central Semiconductor for alternatives, I found these: (2N2894 - 12V, 60/90ns for comparison) - 2N3829 - 20V, 35/65ns - 2N3073 - 60V, 40/100ns - 2N3209 - 20V, 60/90ns - 2N3250A - 60V, 35/50ns - 2N3251A - 60V, 35/50ns high beta --- So it looks like there are better bets out there. Of course, locating them in distribution may be an issue. I have found Octopart is a good place to start: http://octopart.com/ I found 2N3250A at American Microsemi for $7.59: http://www.americanmicrosemi.com/products/search/index.php Steve L.

10 years, 10 months

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test-drb February 2014