test-drb July 2001

test-drb@ccmp.vtda.org

301 participants
824 discussions

by ofenerci＠lynx.dac.neu.edu

Hi everybody, I have a vintage sdk 85 trainer. Please use this link to check it. http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1255923691&r=0&t=0&s… thanks, ozhan fenerci elif_fenerci(a)larose.com

23 years, 5 months

baking tapes

by aek＠spies.com

I was able to find a reference this weekend to baking tapes to reduce binder sticking http://www.unesco.org/webworld/ramp/html/r9704e/r9704e11.htm Recovery Recovery of deteriorated tape and/or signal is an intricate process: what works on one problem may well destroy, or at least exacerbate a seemingly similar problem. Sticky tape can be caused by either binder breakdown, lubricant loss and exuding, or problems with the backing. Don't assume that all problems are the same just because they create similar complications. When carrying out any actions that might reasonably be irreversible - such as baking, or chemical treatments, or buffing the tape - be sure that you are treating the correct 'illness' and are not destroying the very thing you are trying to save. * Baking One of the methods used to temporarily improve binder problems, allowing sticky tapes to be played. The information from Ampex - the developer of the tape-baking procedure - on how long and at what temperature to bake has been variously quoted at several conditions. I checked with Quantegy/Ampex for this paper and they tell me that their recommendations are to a) leave the flanges on the hubs/reels, b) use a high- quality convection type oven or an environmental chamber, and c) bake a sticky tape at 113EF/45EC to 131EF /55EC for up to 36 hours (no R/H given) will sufficiently firm up the binder so that the tape can be played. For 1/4" audio tape, baking for 6 to 8 hours is normally adequate; the longer baking times are for wider tape widths, such as 2" video or audio multi-track masters. Quantegy/Ampex warn, however, that the effect of the treatment is temporary, and it is recommended that the tape be copied within one to two weeks. Although some report having 20-or-more successful 'bakes', there is no published or documented information on how many times a tape can be baked, cycling back and forth between the sticky-firm-sticky succession before it fails completely or before the signal is distorted or altered beyond use. Care should be taken that the temperature is well controlled. One of the specific questions raised is about the potential affect of increased print-through from the baking process. There have been no reports of significant problems, but one source recommends lowering the heat (for example, from 55EC to 45EC) and extending the baking time if there is concern. Regardless of the time and temperature selected, do NOT, I repeat NOT, rewind the tape before baking as this will almost certainly increase print-through problems, according to Quantegy/Ampex. Specifically, unless there is absolutely no other option, the hair-dryer-in-a-box solution does not give adequate environmental controls and is not a recommended solution. Regardless of the sophistication of the oven used, be sure and allow the tape to re-acclimatise before handling it, much less playing. * Environmental conditioning/staging Some have reported notable success with environmental conditioning/staging tape instead of either baking or treatment with chemicals. If time allows, try staging sticky tape at 40EF/4.4EC and 20- to-25% RH (the environment that is being considered for long term storage by a number of the collections represented here today) for several weeks to several months before undertaking more aggressive measures. * Chemical treatments, including addition or replacement of lubricants, is another process that has been developed to recover tape with sticky oxide or loss of lubricants. Like baking, it should be used with the greatest of care. The only such processes known to me are proprietary and have not been made available for public use in any detail. * Cleaning In general, tape cleaning should follow the same basic premise as for any other delicate item: use ONLY as much effort and force as is absolutely necessary. To do even that will probably shorten the life expectancy of the tape; to do more will probably actively destroy it. In general, clean with soft, lint-free cloth, such as 3M's Pellon or 3M's #610 Tape Cleaning Fabric. Use moisture and chemicals sparingly, and only after testing on disposable tapes. Buffing/scraping tape is generally rejected by all with whom I have spoken, unless all other efforts have failed.

23 years, 5 months

Amiga Mosaic source ?

by rachael_＠gmx.net

Don`t know if this is OT but does anyone have the sourcecode for AMosaic ? According to the Amosaic FAQ it was once to be found at ftp.omnipresence.com, but that company has closed some years ago. The file was named MosaicSrc.lha . Regards Jacob Dahl Pind -------------------------------------------------- = IF this computer is with us now... = =...It must have been meant to come live with us.= = (Belldandy - Goddess First class) = --------------------------------------------------

23 years, 5 months

Who wants a Tektronix 8002A uProcessor Lab?

by jweder＠telusplanet.com

I've recently worked a deal with someone on the 8002A, so tough luck for anyone else thinking you might have loved to have another few cubic feet of toys! Hopefully the folks at the post office are in decent shape - I'd hate to be responsible for wrecking anyone's back! Joel A. Weder jweder(a)telusplanet.net 403-556-4020

23 years, 5 months

Apple II for intro to microprocessors

by jweder＠telusplanet.com

While I do agree that the Apple II would be a good machine to study the basics of programming and simple microcomputing, my personal preference for learning about microprocessors is the Motorola 68HC11 EVBU. It's a very inexpensive and compact board featuring the MC68HC11 processor chip. The HC11 has numerous ports allowing serial and parallel I/O, analog inputs, pulse counting, with an RS-232 interface for programming and internal EEPROM for small programs. It's got a decent monitor program (Buffalo) which allows programming at the assembler level, direct access to every function on the chip, and there's a wire-wrap area to add more RAM, an EPROM, motor controls or what have you.... I picked up an EVBU some years ago to use as the heart of a small robot, but put it away when life got too hectic. I've recently got it going again and now have an external 32k RAM, a piezo buzzer, and two relays to drive the robot's motors. I'll be adding optical sensors wired to the analog inputs and eventually even an LCD display and/or a keypad. The 68HC11 EVBU is cheap (if you can still find it), has good documentation, and is a great platform to learn a LOT about microprocessors. The only downside is that it's likely a bit of a steep learning curve for anybody who's really new to the hardware side of things. Joel A. Weder jweder(a)telusplanet.net 403-556-4020

23 years, 5 months

BBC Micro (was: Re: Apple II for into to microprocessors

by pete＠dunnington.u-net.com

On Jul 15, 7:48, charles hobbs wrote: > Tony Duell wrote: > > Over here, I'd recoment getting a BBC Micro. > I lucked out at a flea market about 10 years ago and found one for $15 or > so. It had a US style plug, so I figured it would work fine "over here". It > did, with a few caveats: > > 1. Unlike US micros, which had a TV output on Channels 3 or 4, the > BBC output RF on UHF (Channel 37 or something like that). Of course, > the channel numbers and frequencies used in the US are different than > those in the UK. > > 2. It still outputs a 625-line screen, which my 525-line US TV can only > display a part of (some lines off the top and bottom are missing) > > 3. It outputs PAL color, so a NTSC TV will get a monochrome picture > > (It also supports direct RGB output, so, theoretically, I could wire a cable > that would connect it to a monitor, fixing all of those problems) In a way, you're unlucky -- you have a bit of an oddity. Acorn did sell BBC Micros in the States, but the ones officially shipped had a number of modifications: 110V PSU, VHF modulator instead of UHF, 525-line 60Hz video instead of 625-line 50Hz, "COLOR" keyword in BASIC instead of "COLOUR". I can't remember if they changed the colour subsystem to do NTSC instead of PAL. I think that's unlikely as it would have involved changing the PCB; the changes I know about only required changed to the ROM. -- Pete Peter Turnbull Network Manager University of York

23 years, 5 months

Light Pen for PCjr or PC?

by mbbrutman＠chartermi.net

I've never seen a light pen in use on any machine ... I've only seen them in pictures. How do these things work? Does anybody know how to obtain one or have information on how to build on? Thanks, Mike

23 years, 5 months

thunderstorm damages!

by pete＠dunnington.u-net.com

On Jul 14, 21:40, Eric Chomko wrote: > I've been accumulating the damages from a recent thunderstorm. Wow! > Originally I thought > it was just a GFI breaker and the phones. But it turns out that a > computer got hit (just a PC), > and the cable box as well as a TV. I'm making a list (8 entries so far). > Thank God my bro-in-law > here in Maryland gave me a surge supressor that I put on my SWTPC. Makes > me think I need > more of those things. > > Anyone else have such an event happen? Yes, I've had it happen. Over here, the mains is usually fed from a three-phase transformer, with every third house on the same phase. A few years ago, I was watching the storm pass overhead (I like watching lightning) when the house three along from me had a direct hit on their TV aerial. There was a huge BANG!. The damage to their house was extensive: part of the aerial was vapourised, a few other things melted, much of the electrical equipment in the house was damaged in some way. Almost every burglar alarm in the street went off, and two (on the same supply phase) were wrecked. I wasn't so badly off. The bang was so loud I'd jumped hard enough make a picture fall off the wall. One monitor went bang and stopped working so I pulled its plug. My alarm went off but I was able to reset it. When I'd done that, I had a quick look round to see if anything was on fire, but although a few things had obviously stopped working, nothing looked like it needed immediate attention so I went to help the neighbours with their alarm (there are two old couples whose houses I sometimes look after if they're away). When I came back about an hour later I had a more thorough look. One of a pair of identical modems was fried; the other one was fine. The cordless phone never worked again, but the answering machine on the same line was apparently OK (though it never worked quite as well). The TV and video both died. There was a strong burnt PCB smell in the lounge, which turned out to be the remains of the satellite tuner, which was still drawing power and slowly melting. The monitor that had gone bang was a complete mess inside, and was a write-off, though the one next to it was fine, as was the Acorn Archimedes it was connected to. A PDP-11/34 in the garage had stopped, it turned out that the big input filter on the control box had burnt out. The TV company declared the video recorder to be irrepairable, and the engineer who looked at the TV said it was rather black inside, but they took it away and repaired it -- apparently they ended up changing almost every board inside and it was ages before they brought it back (we had a loan set in the meantime). But if you're thinking of relying on surge suppressors to protect your precious items from a lightning strike: _don't_. They're intended to protect from the spikes induced by nearby lightning discharges, not a direct hit or a strike that hits a nearby transformer or the supply. My PDP-11 is the testament to that. -- Pete Peter Turnbull Network Manager University of York

23 years, 5 months

Mac Rom Debugger (was: Re: Apple II for into to microprocesso rs)

by dhquebbeman＠theestopinalgroup.com

> >MicroBug was first introduced with the Mac Plus and has been a standard > >component in the ROM of all Mac OS computers since then. MicroBug is invoked > >when the system takes a Non-Maskable Interrupt (NMI) and there is no other > >debugger (e.g., MacsBug) installed. > > What debugger did the 128k have in it then? It shipped with > a small switch that pressed both a recessed reset switch and a > programmers switch. The switches were accessed through the side > ventilation slots. We used the switch with MacsBug, MACS = Motorola Advanced Computer Systems... It wasn't ROM-resident, you had to put it on the system disk from whcih you booted, but we'd hit the interrupt switch to drop into it when we needed it. In those days, it wasn't full-screen, but you could redirect the macsBug console to a serial port and debug that way... Regards, -dq

23 years, 5 months

thunderstorm damages!

by dhquebbeman＠theestopinalgroup.com

> I did not suffer a lightning strike, but rain blew a surprising distance > in an open window across the room on my UPS and shorted it out during a > particularly bad T-storm. Fortunately I was in the next room when it > happened since it emitted impressive sparks. I'm the same way! If something's going to go shpritzenshparks, I love to be there to see it. Sort of like train wrecks, I suppose (about 100 years ago, the Big Attraction at the Kentucky State Fair was an exhibit where they collided two steam locomotives head-on!). About 15 years ago, while in an altered state, a severe thunderstorm brought down a 440v (480V? 700V?) line down into pooled water at the end of the street. So much was going on that the utility didn't catch this for maybe 30 minutes. At the pole to which it was still connected, a few sparks were going on, and the lights of nearby homes, which were pretty dim due to the voltage drop, were gradually getting brighter as the voltage would rise. Then, it would rise enough that it would discharge down the felled line into the polled water. I was pretty close; when it discharged, it was like a lightning strike, except with a LOUD 60hz hum. Incredible.. Yeah, and dangerous too, but I'm not interested in living in a Safe World. Regards, -dq

23 years, 5 months

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test-drb July 2001