test-drb September 1998

test-drb@ccmp.vtda.org

154 participants
649 discussions

GUIs 'forced' on people (was Re: Here's something to consider.)

by allisonp＠world.std.com

< If you have free reign and unlimited budget, what you're doing is *NOT* < engineering. Ah, gak another generalization. It does take out the challenge though. < Good engineers want to ship a product that customers will actually use; < the greatest satisfaction an engineer ever has is seeing or hearing < customers use the product. While it is an ego boost to hear customers !You bet! ;) I've done a few. < praise the product, most of the best engineering goes completely unnotic < When was the last time you drove across a bridge and thought "Wow, the < engineers did an awesome job on this bridge."? (At most, people might t < "Wow, this is a pretty bridge.") What people notice is that gee it does save me 20 minutes getting there. A few will notice it as something to look at like Golden Gate or the Verizanio Narrows Bridge. < Any bozo with a EE degree could have built a computer roughly comparabl < in capabilities to the Apple II using many hundreds of chips and costin < thousands of dollars. A good engineer could have done it with few enou < chips to make it affordable. An excellent engineer did it with almost < no chips, and made it not just affordable but also elegant. Ford would < have been proud to see it. Go back to Good, Fast, Cheap. Innovation is the product of careful compromize. I'm also a pilot and In aeronautical engineering given 100hp engine of nominal weight you can make a fast bird that can't carry anything or a very slow one that can and everything inbetween. Somethings however are not possible despite innovations in materials. Allison

26 years, 3 months

CP/M definition

by dastar＠ncal.verio.com

This is from the CP/M FAQ: Q3: Does CP/M stand for anything? A: (Don Kirkpatrick) There are at least three popular answers - Control Program for Microcomputers, Control Program for Microprocessors, and Control Program/Monitor. The issue is clouded by authors of popular CP/M books giving different answers. According to Gary Kildall (the author of CP/M), in response to a direct question on the PBS show "The Computer Chronicles" following Computer Bowl I, the answer is: Control Program for Microcomputers. This is also consistent with DRI documentation. See, for example, p. 4 of the DRI TEX manual. If this is true then someone is lying (perhaps even Kildall himself). Sam Alternate e-mail: dastar(a)siconic.com ------------------------------------------------------------------------------- Ever onward. September 26 & 27...Vintage Computer Festival 2.0 See http://www.vintage.org/vcf for details! [Last web site update: 09/12/98]

26 years, 3 months

Kids these days

by roblwill＠usaor.net

> > Keep scouring those ham fests or swap meets. Check the web for the one > nearest you. If its too far away, convince Dad or Mom to take you by > mowing the lawn and cleaning up your room like you're told :) That doesn't always work. luckily, there's one every year pretty nearby. That's where I got my Tandy 1000 with 4 LPT ports (I don't know how they all work, but they do, and I'm not gonna touch 'em). I was planning on using it as the controller, and hooking up printer guts and making it work by sending line feeds and spaces, and things like through BASIC. -- -Jason (roblwill(a)usaor.net) ICQ#-1730318

26 years, 3 months

Need to bring up a power supply

by dastar＠ncal.verio.com

I don't have a variac or anything and don't have the time or money to get one, but I need to bring up an IMSAI power supply that probably hasn't been powered in over a decade perhaps. What can I do to warm up the caps and transformer before bringing it fully online? Anything? Sam Alternate e-mail: dastar(a)siconic.com ------------------------------------------------------------------------------- Ever onward. September 26 & 27...Vintage Computer Festival 2.0 See http://www.vintage.org/vcf for details! [Last web site update: 09/12/98]

26 years, 3 months

Transformer

by maxeskin＠hotmail.com

As you yourself said, the C128 logic board requires 9vac. But why is this cheap one harmful for electronics? >> >> >> I looked in Radio Shack, at some step-down transformers for 'traveling >> abroad'. There is a price range, with some 'for heating appliances >> only' (the cheapest) and the higher priced ones allow motors, and >> the $34 ones allow electronic devices. What is the difference among >> these units? Also, could a transformer such as in these theoretically >> be reversed and used for step-up purposes? > >The very cheap one ('for heating appliances only') is probably a triac >circuit. Like a lamp dimmer fixed at half-brightness. And that one can't >step up, of course. Don't use that for anything but heaters/lamps. I've >seen the result of plugging a Mac+ into one of those, and it wasn't >pretty. It took me a long time to rebuild the analgoue board. If the >owner had asked me what to do in the first place, I'd have simply cut the >link... > >The true transformers can be used as a step-up unit. But owing to losses, >etc, you may not get the output voltage that you expect (it will, in >general, be lower than you'd expect). But it should work. > >You may find it's cheaper to buy a bare transformer and add the >case/connectors yourself. > >BTW, another trick which I hesitate to mention because it can casue >damage is the following. If you _know_ it's a switch-mode PSU, and that >the first thing it does is rectify the mains, and there's no >line-frequency transformer to provide a startup voltage, then it'll run >on DC, right. So give it DC at peak voltage of the 220V mains it's >expecting - i.e. at twice the peak voltage of the local mains. Make an >external voltage doubler to do this. > >I don't want to give more details, because IMHO if you can't work it >out from that, then you probably shouldn't be doing it. Even if you do >know what to do, examine the PSU carefully to make sure there's _nothing_ >that depends on an AC input. > >-tony > > ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com

26 years, 3 months

Warming up an IMSAI P/S

by CLASSICCMP＠timaxp.trailing-edge.com

>A note in defence of the much maligned Altair while on this subject... >May I point out the the Altair 'B' series machines were one of the first to >provide a main transformer with a multi-tap primary to allow for adjusting >for varying loads and local AC supply. And by this point in time ferroresonant transformers were also being dropped in by folks who weren't happy with the original supply, either. Having used a large variety of S-100 boxes, far and away my favorite power supplies are ones with ferroresonant transformers. Tim.

26 years, 3 months

High density disks on double density drives

by dlw＠trailingedge.com

I've heard that you shouldn't use high density disks in double density drives, that the data wouldn't be reliable. Well, I just bought a bunch of double density 3.5" disks to use with my Apple //gs and I got to thinking about this. Is it because of the drive or the controller? I would think it was the drive, if so, I have the Apple SuperDrive which can read/write high density disks except I don't have the SuperDrive controller for the //gs. Thus I'm stuck with the 800k format. Could I still use high density disks in this drive without problems? Thanks. ----- David Williams - Computer Packrat dlw(a)trailingedge.com http://www.trailingedge.com

26 years, 3 months

GUIs 'forced' on people (was Re: Here's something to consider.)

by allisonp＠world.std.com

< One of the goals of the Apple I was to create a low cost machine. < < Basically I just wanted to give an apple example that not all engineers < all of the time, want to built the biggest, and most expensive things. < That is a bad generalization. It indeed is a bad generalization. As an engiener myself I found it annoying but let it pass. Actually the rules are simple. Good, Fast, Cheap... Pick any two. Enginering is about compromize, tradeoff and innovation. For a given product there are often many ways to implement but more often than not considerations at higher levels may dictate which are the best ways to go. They are not always bad either. If your corperate strategy is fault tolerence the hardware is likely not have extra bits, redundancy and other things needed to make that happen. That can and is more costly. On the other hand if you making really low cost means something else takes precedent. Some thins are a surprize to the uninitiated. For example fewer chips fewer interconnections and connectors often means lower cost and to most people surprize higher realiability. So the idea of Good, Fast and Cheap is not as obvious as first stated. Allison

26 years, 3 months

Warming up an IMSAI P/S

by CLASSICCMP＠timaxp.trailing-edge.com

>Tim wrote: >> And by this point in time ferroresonant transformers were also being >> dropped in by folks who weren't happy with the original supply, either. >> Having used a large variety of S-100 boxes, far and away my favorite >> power supplies are ones with ferroresonant transformers. >I've been told that one shouldn't plug anything using a ferroresonant >transformer into a UPS. Perhaps someone who knows more about the >characteristics of ferroresonant transformers (and UPSes) can explain why, >or refute the claim. Ferroresonant transformers really really want sine waves as input. Many UPS's put out square waves, or slightly shaped square waves. There are many high-frequency harmonics in a square wave, and these disrupt the careful LC-resonance-at-saturation regulation mechanism. Not only do ferroresonant transformers want sine waves, they want sine waves of a specific frequency. I've never tried running a 60Hz unit at 50Hz, but I do know from hard experience what happens at 400 Hz :-(. There are UPS's that do put out nice sine waves, but these aren't all that commonly found. >(*) The only modern thing, anyhow. Did DEC use ferroresonant transformers in >any of their machines? DEC computers from 1970 onwards typically used switching supplies for all high-current supplies, though there are usually some low-current supplies with linear regulators. (There are some exceptions, such as the "large" 8/E using a linear supply while the "small" 8/F used a switching supply)... DEC did sell ferroresonant line conditioners (some of them quite large; one that I passed by took 440VAC 3-phase in and had about 70 15 amp circuits out), but these came before the computer. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology Voice: 301-767-5917 7328 Bradley Blvd Fax: 301-767-5927 Bethesda, MD, USA 20817

26 years, 3 months

Someone was looking for DOS 1?

by cdrmool＠interlog.com

I may be mixing up lists here (must get that procmail filter setup) but I think someone was looking for a copy of Dos (MS) ver 1 or 1.1. If so let me know, I have a disk image of most old versions of IBM/MS dos stored away. Its useless on a hard disk system though as it has no support for them. Just let me know... Colan

26 years, 3 months

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test-drb September 1998