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101090 discussions

Vintage Computer Calendar 2018

by sbolton＠bfree.on.ca

Hey folks; The Personal Computer Museum (http://www.pcmuseum.ca) is offering a beautiful 2018 vintage computer calendar as a fundraiser. The calendars are in hand and the cost is $20 Canadian (no tax). The shipping rates (in CAD) are $3.50 within Canada, $5.00 to the U.S. and $10.50 to the rest of the world. We accept Paypal via our website at http://www.pcmuseum.ca/shop.asp If you don't like Paypal, e-mail me directly for other options! The order page includes a sample of what it looks like. The computers included this year are: IBM PC (1981), Kaypro II (1982), Pencil II (1984), Exidy Sorcerer (1978), Commodore PET 4032 (1980), Apple ][+ (1979), Apple PowerBook 150 (1994), Commodore 64 (1982), NeXTcube (1980), Superbrain QD (1979), Atari 800 (1979), Unisys ICON (1986) If you are interested please reply here or to info at pcmuseum.ca .... The quantities are limited. Thanks for your support!

8 years, 3 months

Otrona / Hospital

by cisin＠xenosoft.com

I was not able to get access to any of my notes to more completely answer Eric's question. Short answer: NO. Otrona did not have two different obscure numbers of tracks for their disk sides. On the limited number of Otronas that I encountered. What I encountered was very straight-forward WD-like ordinarty disk formats. IIRC, they were 10 sectors per track, with 512 bytes per sector. There were 40 cylinder and 80 cylinder. There was a CP/M, and an MS-DOS. I don't remember what the distribution of those formats was, although I specifically remember a 96tpi (800k) MS-DOS. Ironically, the first one that I saw was a doctor at a hospital. To flog the point about portability, Otrona did an early ad with a Chaplin imitator trying to carry a card table with a PC on it down steps in front of a building (capitol?) IBM claimed to own Chaplin (and did apparently pay royalties to Chaplin estate), although Chaplin himself was not a big fan of biug corporation. I wasn't able to answer more fully, nor even now. I just spent a week in the hospital. giant kidney stone and massive infection. First few days were intolerable levels of pain. I am now on 2 weeks of 24/7 IV antibiotic infusions. Bizarre little pump that I carry around, but, at least I'm carrying it around at home, instead of the hospital. THEN, in 2 weeks? they will operate to try to remove the stone. They are hoping to do it with trans-urethral laser, with lithotripsy as a fall back. I had not prepared for being in the hospital, so only had a phone (Samsung Galaxy S4), and it wasn't until the third day that I was able to wrangel access to my pants (and pocket contents) I think that I will recover. THANK YOU to the folk who wrote to me with good wishes! -- Grumpy Ol' Fred cisin at xenosoft.com

8 years, 3 months

Otrona Attache disk format?

by spacewar＠gmail.com

>From the Otrona Attache Technical Manual, July 1983: "The diskettes Attache uses have fourty-six tracks on the top side and fifty tracks on the bottom side, [...]" Really???

8 years, 3 months

H7861 PSU issues

by jnc＠mercury.lcs.mit.edu

> From: Rob Jarratt > when I replaced it and powered on there was a big bang What went 'bang'? (I assume if there was a loud noise, it mus have left visible damage somewhere.) Noel

8 years, 3 months

H7861 PSU issues

by jnc＠mercury.lcs.mit.edu

> From: Aaron Jackson > Picked up a few 555s and sockets and now it works! Congratulations! It's odd that a 555 failed, but sometimes there's no rhyme or reason to what fails. E.g. I was fixing some broken M7859's (KY11-LB Programmer's Console), and on one of them a 7493 (4-bit counter) had died. That's not one of the 'problem' 74xx chips, like ISTR the 7474 being? Noel

8 years, 3 months

RK06 Data Cartridges / Alignment Cart Available (and other stuff)

by billdegnan＠gmail.com

My last email was unclear...I have a few RK06 Data Cartridges and an Alignment Cart Available. Contact me privately if you have an RK06 drive and you're looking for carts. They look like RL02's maybe a hair thinner. I paid a small amt, and I am looking to be reimbursed for the cost. I have no RK06 drive. RK06 cartridges are NOT compatible with RK07's according to the manual. If you're in the Landenberg, PA area stop by, At some point I will publish a list of other DEC items I have in clean organized storage. Bill

8 years, 3 months

Which Dec Emulation is the MOST useful and Versatile?

by jnc＠mercury.lcs.mit.edu

> From: Jon Elson > I'm not sure the original DEC PDP-10 (KA-10) used microcode No, it didn't; in part because it pre-dated fast, cheap ROMs (the development of which was a considerable task in the /360 project - the wonderful "IBM's 360 and Early 370 Systems" covers this is some detail). The KA10 is built out of FLIP CHIPs which carried individual transistors. Another fun KA10 fact: it used 'hardware subroutines' - i.e. a clock pulse would get to a certain point, and get conditionally diverted through some other circuitry, later to come back and continue where it left off. Whee! Noel

8 years, 3 months

DEC BA350s, BA356s, drives, tapes, etc

by useddec＠gmail.com

I have numerous BA350 and BA356 enclosures available along with the power supplies, etc. I will sell separately, or try to configure to your request. Please contact me off list. Shipping from 61820, Champaign, IL area Thanks, Paul

8 years, 3 months

H7861 PSU issues

by aaron＠aaronsplace.co.uk

Hi everyone, I've been trying to figure out what is wrong with the 12V rail on my H7861 (BA11-S) power supply. It's showing about 4.2V. The 5V rail is spot on. Page 39 of the following schematics is the main part board of the PSU. http://bitsavers.org/pdf/dec/qbus/MP01233_BA11-S_schem_Mar81.pdf Going into the collector of Q3 is about 80V coming straight from T2 (I think I measured it at about 100Hz), but the emitter is putting out the 4.2V, which is the same as the base voltage and output voltage. I tried replacing this transistor because the hFE was about 80 and a good one was about 120. Unfortunately it didn't do anything. None of the capacitors look swollen and I don't see any leakage. There is a smaller board which I think goes into J4. The 12V side seems to have a 555 timer and adjusting the pot doesn't change the voltage at all. My understanding of switchmode power supplies is very poor. Does anyone have some pointers on what to check or what might be the possible cause? Hopefully I can get my PDP up and running again... Only got about 20 minutes use out of it. Thanks! Aaron.

8 years, 3 months

An interesting read

by dkelvey＠hotmail.com

Look at Dr Dobb's August 1979. There is an article on computer crime. It is interesting how times have changed. Dwight

8 years, 3 months

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