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drum heads chuck check you company email for pic

by couryhouse＠aol.com

drum heads chuck check you company email for pic Sent from AOL Mobile Mail

8 years, 3 months

Zenith Z-90 startup

by jules.richardson99＠gmail.com

Any Zenith Z-90 owners out there (which appears to be the same thing as a Z-89 / Heath H89, but with a DD soft-sectored disk controller)? I was given one up a couple of days ago which isn't giving the expected "H:" prompt at power-on - but it *does* give a blinking cursor, and hitting off-line lets me type, and characters get echoed to the screen. Right-shift-reset clears the screen and gets me back to the cursor. Before I dig deeper, I'd like to verify that this isn't a feature, i.e. that it's not auto-magically dropping into "terminal mode" at startup :-) Unfortunately while I have masses of documentation for the machine, I'm lacking a basic user guide which might shed light on any such mode; some of the more detailed documentation that I have talks about rerouting the port cabling to use the system purely as a terminal, but doesn't mention doing any other configuration. cheers Jules

8 years, 3 months

Sparc Laptops

by michael.99.thompson＠gmail.com

> Date: Fri, 11 May 2018 23:11:57 -0500 > From: "Sam O'nella" <barythrin at gmail.com> > Subject: Re: Sparc Laptops > > Yes the IBMs are worth tracking down. I always keep my eye out but rarely > see them come up for sale but it'd be fun to have an RS/6000 that doesn't > cause a hernia to move. My only similar one is a tadpole but I don't recall > the version. I used a universal power supply to get it to run for a little > while but then I'm pretty sure the backlight on the lcd popped and went > out. So I'm also a member of the almost but not quite functioning owners > club. :-) Would gladly get rid of some Ultras if I could upgrade to a > portable. > The Tadpole with the 50MHz PowerPC processor was sold as an IBM N40. I have one of those too. -- Michael Thompson

8 years, 3 months

Anyone need KB11-B FMPS?

by jnc＠mercury.lcs.mit.edu

So I've just realized that the KB11-B (the earlier -11/70 CPU, the KB11-C being the later) FMPS is not online; I couldn't find them (but then my Google-fu is notoriously weak, q.v. the Motorola 4015 - thanks all, BTW), but Manx also says: http://manx-docs.org/details.php/1,9214 they aren't available. So, I have a set (got it not too long ago on eBait). Does anyone need these? Only my 8x11 scanner has auto-feed, so I'm not up to doing the whole thing, but I'm prepared to go through and scan the things that are different from the KB11-C (the prints for which _are_ available); the M8133 and M8138, and whatever else is different (flow diagrams, etc). Noel

8 years, 3 months

Restoring a PC Server 500 P/390

by dave.g4ugm＠gmail.com

Folks, I am rebuilding a Microchannel server with a P/390 card. It must have come with a licence for OS/2 Communications Manager as its required to get the P390 working but despite having several boxes of CDs and Floppy Disks I can't find a copy of this software anywhere. If anyone has a copy of CM 2.11 they are not using and would be prepared to sell me., I would be pleased to pay for it. Dave Wade G4UGM & EA7KAE

8 years, 3 months

how fast were drum memories?

by paulkoning＠comcast.net

Drums were used as main memory in a number of early computers, and as secondary memory for a while longer. I wonder how fast real ones (actually constructed) managed to be. What prompted this question is reading an interesting document: https://ir.cwi.nl/pub/9603 (in Dutch), "Principles of electronic calculating machines, course notes February 1948" by Prof. A. van Wijngaarden at the Mathematical Center (now CWI) in Amsterdam. It's quite a fascinating short introduction into computing technology of that era. (One comment in the intro: "The field is new. At the moment, the Eniac is the only working machine..." -- probably not quite accurate given some classified machines, but not too far wrong.) The section on main memory describes a bunch of different technoly possibilities, one of them drum memory. He writes that a drum of 8 cm diameter (a bit over 3 inches) and "a couple of decimeters height" could hold maybe 100k bits, with a track pitch of "a few millimeters". So far so good. He goes on to suggest that such a drum might spin at 1000 revolutions per second, i.e., 60,000 rpm. That seems amazingly high. I could see it being physically possible for a drum of only 40 mm radius, but it sure doesn't sound easy. It's a good goal to strive for given that the logic, even in the days of vacuum tubes, can run at cycle times of just a couple of microseconds. As one more way to speed things up he suggests having multiple rows of read/write heads, where the addressed word would be picked up by whichever head sees it soonest. 10 rows and 60k rpm would give you 50 microseconds average access time which "even for a parallel computer would be a very attractive number". (Pages 17-18) I'm wondering what the reality of fast drum memories looked like, and whether anyone came even close to these numbers. Also, am I right in thinking they are at least in principle achievable? I know I could run the stress numbers, but haven't done so. paul

8 years, 3 months

Next 'stack' of computers to go, IBM p7's - not classics this time

by jnc＠mercury.lcs.mit.edu

> From: Pete Lancashire > NO PACKING OR SHIPPING, must be local pickup. Just a reminded to everyone; most PakMail franchises are prepared to go somewhere off-site, pick items up where they sit, and then pack them; I've used this service several times for 'pick up only' items. Noel

8 years, 3 months

Looking for info on Motorola 4015 chip

by jnc＠mercury.lcs.mit.edu

Hey, all, the RK11-D contoller for the PDP-11 uses Motorola 4015 MSI chips on one of the boards (M7254), but I can't find out anything about them. Google didn't turn anything up, and the appendix in the RK11-D Maintenance Manual that has info about 'all' the MSI chips used in the RK11-D doesn't have this one. It appears to be a quad flop - anyone have more info? Thanks! Noel

8 years, 3 months

Next 'stack' of computers to go, IBM p7's - not classics this time

by jnc＠mercury.lcs.mit.edu

> From: Pete Lancashire > Pak Mail is not cheap Actually, since they buy 'in bulk' from carriers, they are surprisingly reasonable; their quote to ship an H960 rack from Arizona to me was less than I was quoted by some carriers. Noel

8 years, 3 months

Next 'stack' of computers to go, IBM p7's - not classics this time

by jnc＠mercury.lcs.mit.edu

> From: Yvan Janssens <ik at yvanj.me> > ... > I'm located at the other side of the planet. > Would PakMail work for that as well? Pakmail can _send_ to most countries (they can only do _pickups_ in the US and Canada, that I know of), but of course sending a large object a long way can be expensive. I don't know if they can do surface (i.e. boat) to destinations outside North America, or just air - check their Web-site. Noel

8 years, 3 months

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