test-drb April 2003

test-drb@ccmp.vtda.org

272 participants
486 discussions

by melamy＠earthlink.net

Hi Jules, one of the ways to isolate a heat issues is to find a can of cold spray (Chemtronics Freeze Spray). They sell them at electronics stores and places like www.mcmelectronics.com (just searcj for it there). You allow the fual to start and then selectivespray different parts to cool them down. If the fault goes away on a particular device then you have your culprit. best regards, Steve Thatcher Original Message: ----------------- From: Jules Richardson julesrichardsonuk(a)yahoo.co.uk Date: Fri, 4 Apr 2003 10:04:56 +0100 (BST) To: cctalk(a)classiccmp.org Subject: breathing life into old chips hi, this is sort of off-topic as it applies to my TV and not a computer, but I bet some of the folks here can offer advice... :) the microcontroller in the set seems to have developed a fault which only appears when the set's warm. Tracking down a replacement seems to be easier said than done as the chip was obviously discontinued a while back (and then I'd have to worry about the on-board ROM anyway). At the moment though there's no heatsink on the chip - if I do stick a heatsink on it in the hope that it keeps it cool enough to operate, is it still likely to fail at a later date anyway? Once a chip's started to exhibit heat-related problems is that basically the end of it even if something's done about the cooling? I figure some of you people will likely know about these things :) (the chip in question is a ST9293J9B1/AEL for the record, but no infomation appears to exist on the web or on ST's site for it; wish I could get pin-outs to check that it is the chip and not surrounding circuitry that's failing) cheers! Jules For a better Internet experience http://www.yahoo.co.uk/btoffer http://mail2web.com/ .

21 years, 8 months

semi-OT: Power Computing 100 power supply

by cb＠mythtech.net

>What I may do is look for an entire Power 100 machine on eBay (found >one last week, but the seller pulled it unexpectedly before it was due >to end). They're usually pretty cheap. If I end up going that route to >get a PSU, I'd be happy sell you the rest of the parts for cost of >shipping. (Probably ought to keep them for the next piece that fails in >mine, but I don't have the space for that. Plus I will become obsessed >with finding another PSU to make the second PC100 work, so I'll buy a >third, etc.) Obviously if we did this, you would still need a power >supply too, but might be a good way to share the cost of other parts. If you get one, let me know. I probably won't want all the parts, as that will just cause me to want to get TWO PC100's to work (much the same reason you don't want to keep it). However, I would want the SCSI and floppy drive ribbon cables, as even those have been cut in mine. The SCSI cable is trivial for me to replace (I can order one from anywhere, or even pull one from inside an old external hard drive... ironically, I just gave away a cable that would have worked fine since I had it sitting on a shelf unused for years), but the floppy cable isn't as easy, and I would most likely have to buy fresh ribbon of the right size, and swap the ends to it. Not a tough job, but more work than simply buying the cables from your parts machine. I may also want to buy some other parts, like the front panel switches, since those have had their leads cut as well (although those are all fairly easy to patch together). -chris <http://www.mythtech.net>

21 years, 8 months

semi-OT: Power Computing 100 power supply

by mbates＠whoopis.com

Hi folks, Dunno if this is within the 10-year rule or not, but I don't know who else to ask. :) I've got a Power Computing 100, one of the earliest Mac clones (equivalent to Mac 8100/100, though the logic board is physically different). It seems that its power supply has died. It is a Seasonic SSH-200G. I'm pretty ignorant about PSU standards, so am not sure what I need to look for in a replacement -- a friend said "it looks like an AT power supply, but that little 4-pin plug [which connects to the logic board, I think] is non-standard, so a standard AT PSU won't work as a replacement." It also has two large 6-pin plugs that plug into the motherboard as well. The rest of the plugs are standard 4-pin. Does anyone know what would be a compatible replacement? For example, I have been corresponding with the seller of this (which he will relist if I want it): http://cgi.ebay.com/ws/ eBayISAPI.dll?ViewItem&category=3670&item=3409672341&rd=1 which he says is the same except for being 250 watts instead of 200. But the model number's different and it looks a little different in the picture. Thanks in advance, -- MB

21 years, 8 months

Anyone with LP25 Schematics? (or a power board)

by classiccmp＠knm.yi.org

Hi, I've got a DEC LP25 line printer here I just unearthed. I picked it up (ha!) a couple of years back and didn't have much success repairing it. Anyway - I discovered it after my parents tried to move it - oblivious to the fact the cover wasn't screwed on, and dropped it. Looks like just cosmetic damage - but impossible to test as the power board didn't work 2 years ago, and still doesnt. There's some cosmetic damage (read corner it landed on totally smashed) but I don't see any obvious damage to the workings. I've got the maintainance manual, which has the test points in for just about everything, apart from the power board. Only tells me the motherboard voltages, all of which are absent, apart from the 38V you get >from the PSU itself. So if anyone out there has the schematic for the power board in this beast (or even a complete set of schematics) and the ability to scan them in, that would be an enormous help. Also, any ideas for how to prod board with meter when it's in the machine would be useful, as you can only get to one side of the board due to the location of the card in the machine. The cards are plugged into standard edge connectors, with a pair of fingers on the cards themselves. I figure some sort of extender might be my best bet, but how to get hold of such a thing is another matter. I suppose I could always make one :&) Oh - I have a sneaking feeling the paper drive motor is fried (that's my initial thought to why the power board is dead) cause it doesn't look at all sane when you put a meter over it (infinite resistance if memory serves). So where to find a replacement would be nice. Any thoughts on the matter would be useful. It seems a shame to gut it and trash it when I'm sure it *could* be repaired. -- Matt

21 years, 8 months

IBM 5161

by n8uhn＠yahoo.com

Which is why i keep an old db25,ibm, 8 bit, single port "asynchronus serial communications adaptor" (serial port) card around. if you rotate one of the dip jumper packs 90 deg, it goes from async to current loop. try that with a multifunction card (hehe) the pins for current loop are different then the async pins. great for testing out teletypes or old ham gear ;) the other jumper pack sets com 1 or 2 Bill Message: 5 Date: Wed, 02 Apr 2003 20:51:28 To: cctalk(a)classiccmp.org From: Joe <rigdonj(a)cfl.rr.com> Subject: Re: IBM 5161 Reply-To: cctech(a)classiccmp.org At 06:35 PM 4/2/03 -0700, you wrote: >Fred Cisin (XenoSoft) wrote: > >>>>incompatible, and they had a giant surplus of serial (RS232 and current >>>>loop) cards that nobody wanted, so they provided a "FREE" serial card to >>>> >>>> >> >>On Thu, 3 Apr 2003, Tony Duell wrote: >> >> >>>Why did 'mobody' want them? A serial port is a very useful thing to have... >>> >>> >> >>Because they occupied an entire slot (out of 5 on the PC), and other >>companies sold "multifunction" cards that could use the same slot for >>serial, parallel, clock, and memory. Most of those were marketed as SIX >>functions - how many people remember what the other two functions were? >> >floppy, game port BEEP! Nope. Joe --__--__--

21 years, 8 months

Do you recognize these boards?

by patrick＠evocative.com

Does anyone recognize these three boards? I haven't had much luck with Google... http://www.rigneyfamily.com/patrick/ Warning: LARGE graphics... best avoided if you are on a slow connection. --Patrick

21 years, 8 months

Perkin Elmer 550 Terminal and CRT mildew

by ian_primus＠yahoo.com

I recently acquired a nice looking Perkin Elmer 550 terminal. I haven't powered it on yet, as I just unpacked it and it's still somewhat cold >from being shipped, but the person I got it from said that it works. It certainly looks to be in very good condition, I even have the manual. Right now, the only thing that worries me is that there seems to be a little bit of mold or mildew forming under the protective cover on the CRT. I remember seeing this mentioned on a site linked to on a post a while back (http://www.science.uva.nl/faculteit/museum/rampspoed.html). It isn't very noticeable, and only on the very corners, but I would like to clean it off, or at least find a way to prevent it from spreading. What causes this growth? What can be done to prevent it? I have a Hazeltine terminal that has a protective plastic cover, but no mold, and I want to keep it that way. Thanks! Ian Primus ian_primus(a)yahoo.com

21 years, 8 months

Sector interleave (was: H89 CP/M hard-secored boot diskette

by dwightk.elvey＠amd.com

>From: "Fred Cisin (XenoSoft)" <cisin(a)xenosoft.com> > >> > I always wondered, if it was so easy to change the sector interleave on >> > disks to make them load faster, why didn't the original >> > programmers/designers optimize the interleave in the first place? >On Thu, 3 Apr 2003, ben franchuk wrote: >> It depends on your disk hardware and the speed of your computer. >> 1) Computers got faster 2) Disk i/o got dma rather than poiled >> i/o. > >It also depends on what kind of processinbg is being done to it during >loading. For example, dumping file contents into RAM can be done a lot >faster than loading a document into a word-processor. > >The fastest interleave occurs if the system can handle the next sector >immediately after the previous. In that case, the fastest sequence is >plain sequential, and a track can be read in a single revolution. But >when you add extra processing of the data during reading, (such as a word >processor loading a document), you could end up with NOT being ready for >the next sector in time, resulting in the read taking as many revolutions >of the disk as there are sectors per track. Alternating sectors might >reduce that to two revolutions (or skipping 2 sectors, etc.), but that can >easily be twice as long as necessary for a task that did NOT need the >extraneous processing. Most system software developers DO think that >they have optimized it. But they have optimized it for the type of file >access that they EXPECT you to be doing (usually whatever THEY do most). > >BTW, it can be done either by placing the physical sectors in various >orders (such as 1,3,5,7,9,2,4,6,8,10) OR can be done by a translation >between logical sector and physical sector (physical sectors numbered >1,2,3,4, . . . , but data that doesn't finish in sector 1 continues in >sector 3, etc.) > Hi Fred As I recall, most things worked well with just 2 to 1 interleaving. The major problem was how the H89 used the hard sectored. It was guaranteed to wait one extra sector hole, regardless of the speed of the software. This meant that consecutive sectors took an extra revolution+ to find the next sector. I always figured that Heathkit continued to sell the formatter with the 1 to 1 because it made the soft sectored look much better when there really wasn't much difference between the two. This was one of the big claims for upgrading to the soft sectored. As I recall, there was formatter from HUG that was like the one I had. I wrote my Forth because I couldn't justify a separate purchase of HDOS( which I later acquired ). I wrote my own disk interface to FIG's block access. That was when I noticed the slow access and rewrote my formatter. It wasn't until later that I found that all of the HDOS disk had the slow access as well. My H89 was my second computer, after my Poly88. I did find that some BASIC programs worked a little better with a 3 to 1 formatting but that wasn't typical. Even then, writes and read were different. Dwight

21 years, 8 months

Need byte-splitter utility

by pete＠dunnington.u-net.com

On Apr 1, 11:28, Andy Holt wrote: > > What is the difference between odd/even and high/low? > > > On a "little-endian" bus: none > On a "big-endian" bus: flipping the low order address bit :-) > or is it vice-versa. Depends if it's word-aligned or not :-) -- Pete Peter Turnbull Network Manager University of York

21 years, 8 months

H89 CP/M hard-secored boot diskette

by dwightk.elvey＠amd.com

Hi As I mentioned earlier, I have a Forth that runs standalone on hard sectored. Since it is standalone, I've used it to make exact copies of other disk. I've done things like changing the interleaving to make about a 10X improvement in load speeds for many programs. It has been a while since I had the machine running. I can fire it up and check what I have. The only issue I have for making copies for others is the media. I only have a few hard sectored disk. For some reason, I thought that disk formats would last at least as long as 33 lp records. I didn't realize at the time that media was being obsoleted as fast as it was produced. I know better now. Anyway, if I can get it all running, I'll make copies if someone supplies media. Dwight >From: acme(a)ao.net > >Don -- > >Do you have the means to copy such a diskette? I have a set of the original >distribution diskettes here, and last time I checked the boot diskette was >good. > >Later -- > >Glen >0/0 > >> On Mon, 31 Mar 2003, Fred Cisin (XenoSoft) wrote: >> >> > On Mon, 31 Mar 2003, Jason J. Gullickson wrote: >> > > On that note, if any of you know where I could find a copy of CPM and a >> > > compatible C compiler on hard-sectored disks, that would be greeeaaat, >> > > yeah. >> > >> > Don Maslin can probably help you with the CP/M boot disk. But you are >> > going to have to immediately come up with software for serial port file >> > transfer, since that is the only PRACTICAL way to transfer files to or >> > from hard-sectored disks. >> >> I wish that I could, Fred. Unfortunately, I do not have a hard >> sectored boot disk for the H89 to make a copy from so I am >> stumped. >> - don >> >> > There have been several C compilers for CP/M. Aztec/Manx is probably the >> > best, but the most popular was Zolman's BDS C. Good news! As of 6 months >> > ago, BDS C became public domain! : >> > >> > On Thu, 26 Sep 2002, Rich Beaudry wrote: >> > >> > > >> > > Don't know how many of you are on comp.os.cpm, but in case you missed >> > it, >> > > Leor Zolman has decided to release the full retail package of BDS C, >> > > including *ALL* source code (compiler as well!) to the Public Domain. >> > > >> > > http://www.bdsoft.com/resources.html#bdsc >> > > >> > > Check it out! >> > > >> > > Rich B.

21 years, 8 months

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test-drb April 2003