test-drb

test-drb@ccmp.vtda.org

101090 discussions

by wh.sudbrink＠verizon.net

I've recently been restoring an H8/H17 system. Almost all of the problems involved capacitors, including a bad electrolytic in the H17 (diskette unit) power supply. I repaired the H17 supply using a dummy load but apparently the H17 was run with the bad supply before I got it. I say this because some of the tantalum caps on the logic boards of the Wangco model 82 diskette drives popped and/or burned when correct power was supplied to them. I've seen plenty of the "teardrop" tantalums pop, but I've never seen one of the "black suppository" types (used on these drives) go. I believe this was the result of bad ripple in the supply. Anyway, one of the Wangcos now runs perfectly and the other runs fine for a while but fails after about an hour of applied power. The difference between the two is that, on the flaky drive, a cap in series with an inductor did a slow burn, resulting in the inductor having a "nice brown toasty" appearance and a small split in one side that some red resin leaked from. By the way, the only way I know this is an inductor is that it is labeled "L5". It looks like a large beige resistor with too many color stripes on it. Inductors are a weak area in my electronics knowledge. How would you know for sure that one has failed? Does it fail open? Other info: When the drive fails, it can not read any data and, when seeks are attempted on it, it sounds "funny", not the nice sharp click it makes when operating correctly. The inductor does not feel hot to the touch when the drive has failed. I'm out of cool spray. Tonight I will try to apply an ice cube in a plastic bag to it to see if that gets it out of failure mode. Finally, assuming it is the problem, what do I need to replace it? The stripes on it are: Wide silver (covering one end) Red Yellow Brown Gold Thanks, Bill

16 years, 2 months

Solderless breadboarding (was: Re: HP-IB, Amigo/cs80 was Re: hp 9153 floppy & disk)

by joachim.thiemann＠gmail.com

On Wed, Feb 17, 2010 at 13:49, Tony Duell <ard at p850ug1.demon.co.uk> wrote: > The main problem is that those breadboard are terrible. It's not the > clock speed that matters, it's the swtiching time of the IC. Most modern > ICs have ouptus that switch so fast that when you combine them with the > stray capacitances on the breadboard and the relatively high impedance > power connections, you get power and ground lines bouncing all over the > place. Without a _good_ 'scope it's impossible to know why your circuit > doesn't work. If you stick to 4000 series CMOS you'll be alright, but > modern 74xxx familes are pushing it. Really pushing it. But if you're just learning high speed don't matter, even with full computer prototypes. Incidentally, I just saw this: http://blog.makezine.com/archive/2010/02/building_a_cpm_68k_computer_from_s… Crazy, but I'm cheering for him! Retrotastic! :-) Joe. -- Joachim Thiemann :: http://www.tsp.ece.mcgill.ca/~jthiem

16 years, 2 months

Mountain View, CA

by mcguire＠neurotica.com

Is there anyone in or near Mountain View, CA who would be willing to pick up a light PC-tower-sized box and ship it to me? If so, please contact me off-list. Thanks, -Dave -- Dave McGuire Port Charlotte, FL

16 years, 2 months

BBC S.E. news classic computer feature

by roger.holmes＠microspot.co.uk

I'll keep this short, if you are in S.E. England my 1962 mainframe will be on BBC S.E. regional news somewhere between 6:30 and 7pm.

16 years, 2 months

cctech Digest, Vol 78, Issue 24

by jonas＠otter.se

> Message: 12 > Date: Tue, 16 Feb 2010 20:33:58 +0000 (GMT) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: HP-IB, Amigo/cs80 was Re: hp 9153 floppy & disk > To: cctalk at classiccmp.org > Message-ID: <m1NhU7P-000J43C at p850ug1> > Content-Type: text/plain > > some of them may even end up as products :-( I am sure I've told you > how > I once showed a so-called designer who wanted to use a microcontrolelr > module + input interface modules + ... as part of a control system that > his problem could be solved using few lengths of wire and otherwise > unused contacts on his relays and swithces. Hmmm... > > -tony > I used to work for Volvo, developing the maps for ECUs for engine control. One of my colleagues wanted a simple indicator showing the injection time, i.e. for how many milliseconds each engine revolution the injectors were open, to see how his mapping was working out in practice when test driving. He asked for help from the electronics lab, who came up with a proposal for a digital display, all-singing, all-dancing precision device which would cost $$$$$, come in a nice 19" case and take months to design. He went off and made his own indicator instead, using a 555, a moving-coil meter and some passive components. Quite a number of his devices were built for everybody else in the department, IIRC. /Jonas

16 years, 2 months

Living Computer Museum attending the DEC Legacy Event, Windermere, UK, 17-18 April 2010

by RichA＠vulcan.com

Just wanted to let the European readers of CCtalk know that Ian King and I will be at the DEC Legacy Event in Windermere in April, and have been invited to give a presentation on the work we are doing at the Living Computer Museum. Details on the event are available at http://declegacy.org.uk We're looking forward to meeting lots of people there. Rich Alderson Vintage Computing Sr. Server Engineer Vulcan, Inc. 505 5th Avenue S, Suite 900 Seattle, WA 98104 mailto:RichA at vulcan.com mailto:RichA at LivingComputerMuseum.org http://www.PDPplanet.org/ http://www.LivingComputerMuseum.org/

16 years, 2 months

Northstar Horizon and RCA COSMAC Stuff

by brain＠jbrain.com

I've put two Northstar boards on eBay for those who care: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290404578135 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290404577525 And, I've got the following documents that simply need a good home for the cost of shipping: * Original PMMI MM-103 Modem Manual * Copy of Horizon Parallel to Centronics Parallel Cable diagram from Northstar Computers * Bunch of Information from Jay Sage on Z-System he sent me. * Copies of HRAM Original Schematics (Rev A and C) * Northstar 16K RAM Board original manual (RAM-16-DOC) Rev2 Preferably a home with someone who will ensure they are scanned if not already. I also have two COSMAC docs free for cost of shipping: * Copy of MB-604B RCA COSMAC Microboard Computer CDP18S604B * Copy of 1802 datasheet (it's a fax, so it's not a great example, but it's an RCA document, and I could not find a softcopy online) If you know some of these are available as softcopy, please let me know, so I don't feel bad if no one takes them and I end up trashing them. Jim -- Jim Brain, Brain Innovations (X) brain at jbrain.com Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! Home: http://www.jbrain.com

16 years, 2 months

VAX graphics

by bqt＠softjar.se

Richard <legalize at xmission.com> wrote: > > In article <e1d20d631002151910m2cdf9866u4129242000590de6 at mail.gmail.com>, > William Donzelli <wdonzelli at gmail.com> writes: > >>> The VT102 User Guide on vt100.net shows that you could get a green >>> antiglare filter: <http://www.vt100.net/docs/vt102-ug/chapter10.html> >> It is also reasonable to think that DEC did a run of VT100oids with green tub > es. > > I think he's right though. In documentation I've read through, there > were green and amber models offered for the successive generations but > I don't recall having read that the VT100 or earlier models had > anything other than the white phosphor. I think that is correct. I've never seen, nor heard of anything but white phosphor VT100s. *However*, there were clones made by other companies (unfortunately I don't remember any names here), which looked pretty much exactly like the VT100, and which did come with green phosphor. Johnny

16 years, 2 months

COMBOARD (MC68000) hardware hacking (was Re: Solderless breadboarding)

by ethan.dicks＠gmail.com

On 2/18/10, Jim Brain <brain at jbrain.com> wrote: > On 2/18/2010 3:58 PM, Ethan Dicks wrote: >> P.S. - this project revives, yet again, my occasional interest in >> hacking a COMBOARD into something less "embedded" - I usually get >> stuck at the same stage - whether to hack in a 5380 SCSI chip or a >> TTL-based "IDE" interface. COMBOARDs have serial, but no "disk", so >> they'd need _something_ (they already have between 32K and 2MB of RAM, >> depending on the model - I have piles of working boards with 128K of >> DRAM and a COM5025 USART, smaller piles of other models). >> > Send me one and I'll hack in an SD interface complete with FAT support > :-) Heck, I could even put it on the serial port, if you didn't want to > hack it in. I'll go see what I can dig out of the bin - I can easily throw the Fluke 9010A on one and ensure the RAM and ROM test out OK. It's harder to test out the bus interface, but unless you plan to stick this on a Unibus, I don't think you care if the 8641s are all 100% known-good. ;-) The basic board is 8MHz 68000, 128K of parity DRAM (array of 4164 DIPs) on a 74S409 DRAM controller, 2x 28-pin JEDEC ROM sockets (2764s at least, if not 27128s), a socketed COM5025 which could be a good place to tap into the data bus and some select lines, an MC6821 with a 16-pin DIP exporting at least one of the 8-bit ports ("programmers' interface"), some sort of sub-100Hz timer, IIRC, for heartbeat interrupts, two 40-pin off-board BERG connectors (one for sync serial, one for LP05-type printer, driven by the rest of the MC6821), and 12 edge-visible power and status LEDs (mostly serial status indicators). I'd send you a link to a picture, but I don't seem to have posted one (and the salad days of Software Results pre-date the Web). It's a hex-height card that expects to pull +5V, +15V and -15V of of the Unibus, so you'd have to either plug it into a DEC module block or hack in power somewhere. Naturally, I have all the schematics and PAL equations, but they are in paper format, not electronic. Overall, my recollection is that the memory space is divided by A23 and A22 into four 4MB quadrants, RAM, ROM, I/O, and Unibus DMA engine. Retooling PALs could, of course, alter that. Unfortunately, the PALs are not always socketed (depends on the age of the board) and it's a six-layer PCB. I know of no reason PALs couldn't be replaced with 16V8 and 22V10 GALs, but it hasn't ever been tried. Still interested? -ethan P.S. - the other models are variations on the theme. The older model has 32K of 2114 SRAMs and two 6309 PROM sockets, newer models (of which I have only a handful) have 41256 or 44256 DRAMs and Z8530 DUARTs, but are otherwise quite similar architecturally, if you ignore the specifics of the host bus interface.

16 years, 2 months

Device Side usb floppy interface finally shipping ($55)

by aek＠bitsavers.org

http://www.deviceside.com/ talked to this guy at VCF years ago.

16 years, 2 months

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