test-drb September 2008

test-drb@ccmp.vtda.org

220 participants
323 discussions

by chrise＠pobox.com

I have a large collection of paper tapes that came with a vintage Altair 680b and Teletype model 33 that I inherited. I've restored the machines and have started looking at the tapes. Unfortunately, I have discovered that the rubber bands that were used to keep the tapes rolled up have all dissolved into a yucky gooey mess that is in most cases, stuck to the tapes. I'm pretty sure the oil on the tapes and 30+ yrs time have done this dirty deed. Sadly, there were original, unopened MITS Altair editor/assembler tapes, BASIC, etc. still sealed in their original packaging but the rubber bands inside have melted all over the tapes. Has anyone dealt with this kind of cleanup before? What are my best options for solvents to get rid of what's left of the rubber without damaging the tapes too much more? What a mess. Parents, talk to your children about rubber bands... Chris -- Chris Elmquist mailto:chrise at pobox.com

15 years, 10 months

ECC on MFM drive

by ra9yer＠yahoo.com

Hello, Could someone help me understand the algorithm used for data integrity check on ST251 MFM drive. I have ST251 drive and an Adaptec controller. Also I have ability to view recorded data in raw format. On the track I see ID field block protected by CCITT CRC16. And the data block protected by some 32-bit ECC. This is definitely not a CRC32. The algorithm in general looks like shift register for polynomial multiplication with polynomial equal to x32+x28+x26+x19+x17+x10+x6+x2+1 . But, this is not just a multiplication. The circuit has some other logic that I did not understand yet. I?ve found very useful document (http://www.national.com/an/AN/ AN-413.pdf) It has a mention about algorithm called ?Glover 140A0443 ? May be this is that I have? Please advice. Thank you. Alexander.

15 years, 10 months

vac tubes / was Re: Schematics of Atanasoff-Berry

by ajp166＠bellatlantic.net

> >Subject: Re: vac tubes / was Re: Schematics of Atanasoff-Berry > From: ard at p850ug1.demon.co.uk (Tony Duell) > Date: Sat, 06 Sep 2008 21:34:08 +0100 (BST) > To: cctalk at classiccmp.org > >> > I really don't understand this modern love with making things as >> > small and light as possile. I'd rather have things that are heavy >> > enough to stay put (in the case of a rack unit, not to topple, or >> > even feel wobbly when units are extended ot the maintenance position) >> > and that are large enough for me to be able to work on them. > >[For the record, I consider the OP's comment that he wants to use a PC >PSU becuase he has one or that it's convenient, or.. to be entirely >reasonable.] > >> >> Bigger and heavier means less items in your collection to fit in the >> space, and a smaller number before the floor falls out from underneath >> of it. I'd hope you could appreciate that. :) > >So by that arguemnt we should all collect handhelds, not desktop and >rack-mounted machines :-) > >> Another problem I seem to have is that the heavier an item is (and >> harder it is to move myself), the less I seem to be able to find people >> to help move it. > >Fortunately I don't mind having to dismantle something to move it. Many >of my larger machines came into the house in small-ish pieces. I >remember, for example, dismantling a DEC RA60 on the back of a friend's >pick-up truck (fortunately the RA60 is dismantled from the top down, so >this wasn't hard), taking the bits inside and then putting them back >together. > >Gettign back to the OP's heater supply, I don't think a mains-input >heater transformer to supply 5 normal-sized receiving valves is going to >make the device impossile to lift. If you used ECC83s (12AX7s), I think >you could use a 20VA transformer with no trouhle at all, and that's >hardly large or heavy. > 12AX7 at 12.6V @.15A (1.8VA) or parallel connected 6.3V @ .3a and I consider that trivial. A transformer sufficient to run 10 of those (18VA) is under 2-3pounds. The average 12V at 1A wall wart can run six of those with a comfortable margin. We are not talking a lot of power yet. If we are in the realm of 100 or 1000 of those then we have some power needs to deal with.. The solution there would be to use instead of one 12.6V transformer that can give 150A we can use ten more readily available transformers of a mere 15A (189VA) which is more manageable anyway. That same transformer (assume 12.6V AC) could using a voltage multiplier easily supply 40-45V where the valves would have a decent usable performance. This is easy as those valves at 40-50V will only need a few milliamps per plate circuit. I know this as I built a 5 tube reciever (6AN8, 6AU6, 6BH6, 6CW4, 6dl6/ECL84) for 80/75M and the whole radio fits in a 7x8 chassis and with the power transformer and audio output transformer is under 6 pounds. The transformer used was salvage but had a 150V 100mA winding and a 6.3V 3A winding (total of 34VA) and that was not even stressed hard and weighed on at under two pounds. Another example is 40 years ago I had a Beckman EPUT (events per unit time) counter that used the then typical tube era 5mhz ring counter decades with neon readout (0-9 with NE2 type neon behind them) (6 ofthem) plus timebase for a whopping 42 tubes mostly of the 12AX7 types and it was big (19" rack width by 11" high) but I distinctly remember it as barely 40 pounds considering it was fully enclosed in a steel case and each decade was in its own case that plugged into a matching socket in the cabnet. Powering tubes in that class (ECC83s) is trivial compared to the day of the ABC where typical dual triode was maybe in the class of 6SN7 (6.3V at .6A) or worse. Early tubes where power hungry for heater power. Allison > >> I in no way said that I wanted everything made of lightweight (and >> easily breakable) plastic, it's just annoying when things are severely >> over-enginered and thus increase the weight, or use heavier components >> when lighter ones would work in a perfectly acceptable manner. > >Well, there are limits, but I must admit I tend to admire solid >overengineered devices. > >-tony

15 years, 10 months

ECC on MFM drive

by aek＠bitsavers.org

> I have ST251 drive and an Adaptec controller. Look at the chip set data sheets on bitsavers.

15 years, 10 months

[Toronto Canada] - AES Plus free for collection

by john_a_s2004＠hotmail.com

Hi, I have had an email from an owner of an AES Plus system, who is looking to give it away to a good home. This system is a dedicated Word Processor, built around an 8080 processor. The owner has loads of disks too, these might be rare 16-sector hard-sectored types and so it would be worth collecting the system just for the floppies. If you are able to collect the whole system from the Toronto area, please email me and I will pass your details on. Regards, John _________________________________________________________________ Make a mini you and download it into Windows Live Messenger http://clk.atdmt.com/UKM/go/111354029/direct/01/

15 years, 10 months

IBM memory available

by pat＠computer-refuge.org

I've got a bunch of DIMMs pulled from RS/6000 SP hardware available for not much cost. The memory is 3rd party (Kingston) 512MB DIMMs that were used in Purdue's SP high node systems. Third-party memory doesn't seem to be worth much, so I'm not asking too much, say $10+shipping per set of 8 or so. These are equivalent to IBM FRU 07L9758, F/C 4121 or 4100 This memory works in at least the following systems: 7044-170 (44P-170) 7044-270 (44P-270) pSeries 640 / B80 pSeries 620 9076-270 thin/wide and 9076-N81 SP high nodes Pat -- Purdue University Research Computing --- http://www.rcac.purdue.edu/ The Computer Refuge --- http://computer-refuge.org

15 years, 10 months

lead-free solder (was: Setting up a VAXstation)

by halarewich＠gmail.com

heres a link to some lead solder http://www.acehardware.com/product/index.jsp?productId=1290635&cp=2568443.2… Chris On 10/2/07, Zane H. Healy <healyzh at aracnet.com> wrote: > > At 11:37 PM +0100 10/1/07, Tony Duell wrote: > >For the first part, I'd offer to do it for you, but it would be illegal > >to do so. Owing to our totally daft laws, (a) I'd have to use lead-free > >solder, which I don't have, don't trust, and am not set up to use and > > How hard is it to work with lead-free solder, and is it becoming a > problem to get traditional solder in the US? I've been meaning to > pick up a few rolls. As I'm still using a roll purchased in the 80's > from Rat Shack for building a couple things for my VIC-20, I haven't > been going through it that fast. Though I seem to be using it more > often now than. > > >(b) > >it has been said that if an enthusiast (specifically a model engineer, > >but it would apply here too) does jobs for others, then his workshop > >becomes a workplace and is covered by all the daft health-and-safety > >rules that I have no desire to get involved with, and which quite > >honestly, would stop me from getting on with things. > > Does it count as a job if you don't take payment? > > Zane > > > -- > | Zane H. Healy | UNIX Systems Administrator | > | healyzh at aracnet.com (primary) | OpenVMS Enthusiast | > | MONK::HEALYZH (DECnet) | Classic Computer Collector | > +----------------------------------+----------------------------+ > | Empire of the Petal Throne and Traveller Role Playing, | > | PDP-10 Emulation and Zane's Computer Museum. | > | http://www.aracnet.com/~healyzh/ | >

15 years, 10 months

Interesting driver...

by geneb＠deltasoft.com

While reading comp.sys.cbm, I ran across this site: http://simonowen.com/fdrawcmd/ I would imagine that this driver would come in quite handy for those wanting to work with foreign formats while using Windows. g. -- Proud owner of F-15C 80-0007 http://www.f15sim.com - The only one of its kind.

15 years, 10 months

Mac SE Flyback!

by julianskidmore＠yahoo.com

Hi folks, I hope a Mac SE is old enough to chat about here - it's hardly newer than my pdp11 or Vax! Anyway, the Mac's good, but the flyback Transformer burnt out a while back and I was wondering what would be a suitable replacement. I have information on the Mac Plus analog circuitry from Mac Tech and the parts numbers for the Mac SE flybacks. However, none of this gives me the spec for the flyback and since AFAIK they're not available any more, I'm wondering how to get a suitable replacement. It doesn't have to look the same, it just has to work and be reliable! http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html Tai-Ho/Taiwan R.O.C. TH-1565C Mac SE Lifon/Taiwan R.O.C. 157-0042-A Mac SE, Repaired analog board, SE/30 Lifon/Taiwan R.O.C. 157-0042-B Mac SE, Repaired analog board, SE/30 Lifon/Taiwan R.O.C. 157-0042-C Mac SE, Repaired analog board, SE/30 http://home.earthlink.net/~gamba2/images/plus_analog.PDF This is probably going a bit far ;-) : http://members.misty.com/don/samflyhv.html -cheers from julz @P

15 years, 10 months

FORSALE: IMSAI 8080 in excellent shape

by michaelgreen42＠comcast.net

Picked up a recent acquisition and thought I would try here before I send to eBay. I have an original IMSAI 8080 in great condition. It comes with two floppy drives. I don't really know how to test but it powers up and all the blinking lights come on. Taking best offer of cash/trade. I'm located near Seattle WA. Obviously if you're local trades will be easier. Email me with offers.

15 years, 10 months

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test-drb September 2008