test-drb December 2014

test-drb@ccmp.vtda.org

179 participants
207 discussions

by derschjo＠gmail.com

Anyone have any documentation on the RGS 008A? This is an early (1975) microcomputer kit based on the 8008, and was reviewed in the first issue of BYTE. Other than that article, there's not much information out there; anyone happen to have the manuals (or anything else) and be willing to scan them? Thanks, Josh

10 years

2 new old stock Memorex MRX IV 6250 BPI SuperReel Tape

by mazzinia＠tin.it

I'm not the seller, nor related with them in any way. This said, apparently these are new old stock (pics show sealed in plastic), and they ship internationally. http://www.ebay.it/itm/2-Nastri-Memorex-MRX-IV-6250-BPI-SuperReel-Tape-VAX-D EC-IBM-Vintage-/371205354623?pt=LH_DefaultDomain_101 <http://www.ebay.it/itm/2-Nastri-Memorex-MRX-IV-6250-BPI-SuperReel-Tape-VAX- DEC-IBM-Vintage-/371205354623?pt=LH_DefaultDomain_101&hash=item566d90347f> &hash=item566d90347f

10 years

Help with a busted MSV11-L?

by jnc＠mercury.lcs.mit.edu

PS: When buying replacement chips, since many are NOS, which manufacturers should be avoided, and which are good? I recall there was some discussion on here a while back about the topic of which vendors seemed to have the most problems with chips failing, but I can't find it (and a bit of Google searching couldn't turn up anything on the topic - all my searches turned up too much other stuff). And should I always install the replacements in sockets, or is it OK to just go ahead and solder them straight in? (The socket obviously doesn't cost much, and I'm less likely to damage the chip installing it like that, and of course if I get it in and it's U/S, it's easy to swap out from a socket, but I'm wondering if the use of a socket has any downside, electrically.) Again, thanks for any advice (and I won't be surprised if the last starts the usual debate... :-) Noel

10 years

The 9406-270 - OS and Other Products Installed

by Kevin＠RawFedDogs.net

Classic Computer Fans, I made it through an i5 OS install on my 9406-270 plus installed various products. I haven't done much past that other than switching the QCTLSBSD system value from QBASE to QCTL and performing an IPL. I'm now able to perform an unattended IPL and get from power on to a sign-on screen in just under nine minutes. Only one drive came up to choose from during the install process so everything is installed on it. A WRKDSKSTS shows drive 1 at 33% and drive 0 unused. Is it possible to add drive 0 to the system at this point? I'm not sure where to go from here. Some of the things I can think of that I'm sure need to be done at some point: - Learn how to apply PTFs - Create some user profiles - Configure and start TCP/IP - Explore backup options in case I have to reinstall or restore every 69 days. I'd be surprised if the internal tape drive is functional. - Learn all kinds of things I haven't even heard of yet And I'm sure the list goes on and on. I'm open to suggestions. -- Kevin http://www.RawFedDogs.net http://www.Lassie.xyz http://www.WacoAgilityGroup.org Bruceville, TX What's the definition of a legacy system? One that works! Errare humanum est, ignoscere caninum.

10 years

Origin or 1.44 MV FD label [WAS: RE: Weekly Classic Computer Trivia Question (20141205)]

by t.gardner＠computer.org

>-----Original Message----- >From: Fred Cisin [mailto:cisin at xenosoft.com] >Sent: Saturday, December 06, 2014 12:40 PM >To: General Discussion: On-Topic and Off-Topic Posts >Subject: Re: Weekly Classic Computer Trivia Question (20141205) >>On Sat, 6 Dec 2014, Johnny Billquist wrote: >> I should actually do my math before commenting. :-) It just happens, >> that by a funny accident, 1440*1024 is actually 1,474,560. >> >> But still. The actual size of the floppy wasn't decided because you >> pulled out 1440*1024, but because of the format of the darn thing. >> 1.44MB is just the closest "nice" number you can come up with after >> the fact as a way to talk about the capacity of the thing. >> >> It is not an exact number, but they seldom are, when we talk about >> storage. People like to round things off, to make it easier to talk about. >It is NOT a "nice" number. >Honest numbers would be either 1.47 or 1.4 There is no legitimate way to come up with 1.44 unless you cheat and MIX powers of 10 and powers of 2. __________________ It comes from a double capacity 720 KB FDD - which in this case are actually KiB and not kB However, in an incredible bit of marketing stupidity it was labeled 1.44 MB, since 2*720 KB/1000 = 1.44 MB Tom

10 years

Acceptable Ripple

by robert.jarratt＠ntlworld.com

Just checking a PSU in a MicroVAX 3100 Model 80. I am measuring about 10mV ripple on the 5V supply and 20mV ripple on the 12V supply. Does that seem reasonable? I am not sure if it is a scope artefact, but there appear to be large spikes at the top and bottom of each sawtooth. The machine appears to partially work, it seems to be getting some errors during the memory test, but I don't know if that is the spikes I am seeing or just a bad component somewhere. Regards Rob

10 years

Help with a busted MSV11-L?

by jnc＠mercury.lcs.mit.edu

>> From: Jon Elson >> The 2V level sounds like maybe NO chip is driving that node. A shorted >> output (or input) would likely pull one way or the other, 2V is about >> the resting point of a TTL input. > The way the two output data laches are wired, the output control on one > is wired with the negation of the output control on the other, so one > or the other ought to be trying to drive the line at all times. So > perhaps the one that _should_ be driving the line normally is the bad > one, then After thinking about this tip for a few minutes, it dawned on me that there's a simple way to see if the data latch is bad: read the CSR! That will try and drive that line from the other latch. So I did, and ... I can read 0 from that bit in the CSR! So it's the data latch that's bad. Thanks for the tip! Noel

10 years

Help with a busted MSV11-L?

by jnc＠mercury.lcs.mit.edu

> From: Jon Elson >> the anomalous voltage I see (2V) is after the output (i.e. to the >> QBUS) data latches, but before the bus transceiver > Output from the memory chips? Well, then, you may have to replace them > all, as one chip may be jamming the bus. No, "after the output .. data latches", which are between the memory chips and the bus transceiver. > Do any of the affected driver chips run hotter than the others? That's > the "finger test", you replace any anomalously hot chips first That's a useful idea, thanks, I'll try that. > The 2V level sounds like maybe NO chip is driving that node. A shorted > output (or input) would likely pull one way or the other, 2V is about > the resting point of a TTL input. Ah, more useful info. The way the two output data laches are wired, the output control on one is wired with the negation of the output control on the other, so one or the other ought to be trying to drive the line at all times. So perhaps the one that _should_ be driving the line normally is the bad one, then (since it's clearly not...) Thanks for the tip! Noel

10 years

Help with a busted MSV11-L?

by jnc＠mercury.lcs.mit.edu

> From: Jon Elson > Power the system off for 10 minutes, then power on and read various > locations. If data bit 4 shows 1's and 0's, then the reading is OK, and > it is the writing path that is stuck. I'm not sure this will work, as the anomalous voltage I see (2V) is after the output (i.e. to the QBUS) data latches, but before the bus transceiver: i.e. in the output (reading) path. So I know it's the output data path that has a problem, not the input. The only question is which of three chips on the output data path might be the cause of the problem; one of the two three-state latches (one for memory data, one for CSR data), or the bus transceiver. As far as I can tell, those are the only three devices attached to that conductor (where I see the constant 2V). Noel

10 years

Help with a busted MSV11-L?

by jnc＠mercury.lcs.mit.edu

Hi, all, I'm trying to fix a broken MSV11-L card (M8059-KF). The symptom is that it always reads back with the 020 bit set, but otherwise appears to be fine. (E.g. you can write a number in 0, and a different number in 020, and each reads back OK, with the exception that the 020 bit in each is always set; i.e. the addressing is working fine, as is the QBUS generally.) So poking around with my 'scope, I find that the latched D04 signal ("LAT D04 H") is always around 2V - not good! From the prints: http://www.mainecoon.com/classiccmp/MSV11-L/MSV11-L%20FMPS%20MP01238%20(M80… it appears to be generated on page 6 of the prints (page 10 of that file), as the wired-or output of two octal 3-state-output latches (E57 and E64, an 'LS373 and an 'S373 respectively). The only place it appears to go is to the quad bus transceiver (E62, an 8641), on page 2. My question is: any guesses as to which of the three is causing this? Or do I just have to start replacing them until I find the guilty party? :-) If so, what's the best order to do so in? FWIW, the two octal latches are both TI Malaysia parts (date code 8231), and the transceiver is a Motorola (date code 8249). Thanks in advance for any help! Noel

10 years

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test-drb December 2014