test-drb

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Laugh, it's funny

by evan＠snarc.net

http://www.theonion.com/articles/computer-company-started-in-garage-30-year…

16 years, 1 month

MIPS CPUs

by classiccmp＠philpem.me.uk

(Taking this into a separate thread, it has nothing to do with disc analysers). Cameron Kaiser wrote: >> As I understand it, you can design a MIPS chip based on the published >> specs and not have to pay any licensing fees. There was a patent on the >> unaligned load/store instructions, but that expired in 2006 AIUI. > > That's probably why the Chinese have jumped on it (Godson/Loongson), not > that they worry excessively about licensing, but anyway. It's probably why there are so many open-source MIPS cores on Opencores too. I've been playing with UCore this evening and tweaked it to run at about 80MHz on an Altera Cyclone II. Unfortunately the feature list on Opencores is for a newer version of the code, which was apparently never uploaded :( I've got a few 'suspended projects' that would benefit from having a reasonably fast (~100MHz would be nice, ideally with a bit of I-cache and D-cache), 32-bit RISC CPU core with decent compiler/RTOS support. Ucore seems to fit the bill (although there are reports that it doesn't work properly) but the "older version" of the code has support for instruction or data caching :( :( (That and I'll need to rig up some form of bus arbitration scheme to merge the Instruction and Data buses together... now won't that be fun.. at least it's WISHBONE compliant, I suppose) -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/

16 years, 1 month

IBM Monochrome "Black and White" Parallel card double image

by billdeg＠degnanco.com

I am working with an IBM Monochrome "Black and White" Parallel card that is showing a double image. I noticed that the 106 / 16+ tant cap at the top left near where C1 / U47 is printed was broken off the board so I put in a new one. There was no change. I tried another cap, no change. I removed the cap entirely, no change. I am looking for a schematic/docs/suggestions. It looks something like this: ------------------------------------------------- -128K 128K - - - - - - - - - - - - - - - ------------------------------------------------- Thanks.

16 years, 1 month

IBM Monochrome "Black and White" Parallel card double image

by billdeg＠degnanco.com

>> > This is one of the original black connector versions of the IBM >> > 1904057 XM 407 display cards. It has 9114 RAMs in it, not socketed of >> > course, so I think if I can probe each RAM chip first to ID the bad >> > chip it'd be more efficient. I would similarly have to check the >> > 74L chips. oy! >> > > I know this is a stupid question, but have you scoped the sync > signals from the card? > > --Chuck > > No, I did not. Unfortunately this is not my forte. Bill

16 years, 1 month

Reusing old floppy *drives*

by lproven＠gmail.com

Noting the discussion on old media, a slightly different question. Please excuse my profound ignorance on matters electronic! I have read, somewhere, that it is possible to connect HD floppy drives to elderly kit that is only expecting DD drives, and use them for just DD operation. More specifically, I'd like to resurrect my ancient Sinclair Spectrum with its MGT DISCiPLE disk interface. Way back in the 1980s, I used 5?" media, as they were still cheaper. However, now, I daresay I won't find any new 5?" media and even 3?" DD media are getting tricky. So what I was considering doing was connecting a pair of old PC floppy drives - 3?" HD (1.4MB) floppies - and quite possibly using 1.4MB media, but only formatting them to 720K and using them as 720K. IIRC, the drives permit this. The track widths are the same - both are 80t drives - it's just that DD used 9 sectors per track and HD 18. Is this likely to work? I realise I'll need to find drives with a unit selection jumper on them, so I can set one as 0 and the other as 1; no twists in the cables this far back, & I'm guessing that a twisted cable wouldn't work with a controller that wasn't expecting it...? -- Liam Proven ? Profile: http://www.linkedin.com/in/liamproven Email: lproven at cix.co.uk ? GMail/GoogleTalk/Orkut: lproven at gmail.com Tel: +44 20-8685-0498 ? Cell: +44 7939-087884 ? Fax: + 44 870-9151419 AOL/AIM/iChat/Yahoo/Skype: liamproven ? LiveJournal/Twitter: lproven MSN: lproven at hotmail.com ? ICQ: 73187508

16 years, 1 month

chemistry simulator on Apple ][?

by adamg＠pobox.com

Dave McGuire wrote: > A local friend is looking for an old chemistry simulator program >for the Apple ][. Here's his description: > >> I'm trying to find a "chemistry simulator" program that I used to play >> with on an Apple II way back in the day. I don't remember the name of >> it, but I remember being able to build a decent "lab" out of parts and >> pieces. I remember that the first lesson was an experiment to figure >> out why the fertilizer ship in Texas City exploded after an onboard >> fire. This was called Chem Lab, and I think it was published by Simon & Schuster. -- Adam

16 years, 1 month

Wanted: Graphics card and drive sled for RS/6000 7046-B50

by dm561＠torfree.net

Date: Tue, 23 Mar 2010 19:16:50 -0400 From: Sridhar Ayengar <ploopster at gmail.com> Subject: Re: Wanted: Graphics card and drive sled for RS/6000 7046-B50 M H Stein wrote: >> I recently bought an RS/6000 7046-B50. It didn't have a graphics card >> installed (I can use it over a serial console, but I would prefer to be >> able to use a graphical console). It is also missing the drive sleds. >> Does anybody have a graphics card or drive sled that would work with it? > > ---------- > A few days ago I posted here about an RS/6000 available in the Toronto > area but there was no interest either here or elsewhere, so it's being > scrapped on Thursday. > > This is an RS/6000 Power Server 520, Type 7013, Model# 26-10855; > If it has a graphics card would it fit in yours and what would the number be? > And are the sleds compatible? Neither would be compatible. Peace... Sridhar ------------------------------ Thanks for that info, Sridhar; I googled the 7046 and yes, it looks like it's at least ten years newer than mine which I think is one of the very first RS/6000s, and a completely different machine; too bad. mike

16 years, 1 month

Leaving computers on... (was Re: Disc analyser news update)

by pcoghlan+cctech＠vms.eurokom.ie

> >Another very common one is that the startup resistor of a switch-mode PSU >goes open-circuit while the machine is left on The PSU keeps working as >long as the mains is there, but if it gets turned off, or the mains >fails, of course it won't restart. > >Some terminal servers and the like were very prone to this problem. > >It's a very easy fix once you know which resistor to check. > I've had a slightly related fault in the switch-mode power supply (wall wart) of a Decserver 90 terminal server. A small electrolytic smoothing the supply from the startup resistor had lost capacitance. Lisening closely to the power supply, I could hear a high pitched whine which made me think there was a good chance this was normal vibration of the chopper transformer and threw me right off finding the real problem. When the capacitor was replaced, the whine went away and the power supply worked correctly, for a few weeks before it failed again. I haven't had the heart to investigate further. Regarding Dec equipment, recent experiences are making me speculate that leaving some items turned off for a few months might be bad for them! - An Alpha 3000/300 in continuous use for several years was retired. When I next turned it on several months later, it gave a loud bang and emitted smoke from the PSU. This turned out to be from a VDR which had exploded due to a triac shorting. (This wasn't easy to track down as the VDR had been sleeved with rubber which completely hid the problem.) The function of the triac was to automatically switch between 115V and 230V input. Its shorting left the PSU permanently in 115V mode and the power around here is 230V. Replacing the VDR (after a good bit of fun tracking down a suitable replacement) and snipping out the triac (which I couldn't find a replacement for) solved the problem at the expense of being able to operate on a 115V supply. - A HSZ80 disk controller, like the 3000/300, also failed with a loud bang, without smoke though, making it difficult to figure out which of the many items plugged into the extension lead had blown the house fuse this time. An unmarked item across the mains which looks like a VDR or disc capacitor had shorted. I can't replace it as I have no idea what its spec is. - A Vaxstation 3100, also in continuous use for several years was similarly retired. In service, it had suffered very occasional memory failures but nothing persistent. When I switched it on a few months later, several problems were apparant. Firstly, one of the fans in the PSU ran for a short while and seized. Secondly, the memory power-on test failed to complete. It didn't report an error but the machine reset in the middle of the test and went back to the beginning of the power-on tests in an infinte loop. It's not supposed to do that! Removing both 4MB memory expansion boards got past that problem but resulted in a horrible error from the SCSI driver on attempting to boot, presumably because there was not enough memory on the motherboard. Replacing one memory board (either one!) got by this problem but it then became apparant that the disk was failing with lots of clunking and clicking and various errors reported. Finally, the "compose" light on the keyboard remains lit all the time which as far as I recall may be intended to indicate that all is not well in some part of the system in the event that nothing appears on the graphics console. - A Microvax 3100 model 80 retired for some years was quite happy to perform correctly for a few hours when switched back on. However, after later shutting down and restarting, it died in the middle of the memory test and produced no console output since. It's been a while since I looked at it and I can't remember what indication the diagnostic leds gave. I'm sure if they gave any useful lead I would have followed it up though. Sometime I feel like my kit is failing quicker than I can get around to fixing it. Regards, Peter.

16 years, 1 month

IBM 7374 and HP Draftmaster II info needed

by starbase89＠gmail.com

I am trying to dig up information on these two plotters to make them more sellable. They are among the flotsam amassed by Infoage, and just take up space. Thanks Joe

16 years, 1 month

semi-OT: do you routinely attempt projects out of your comfort zone?

by keithvz＠verizon.net

Do you routinely attempt projects out of your comfort zone? While I think it is the right thing to do intellectually to expand my knowledge, I often think that I waste a lot of time trying to do fairly simple tasks in areas where I have limited knowledge or experience. I think challenges can be rewarding, and I enjoy them. "Anything worth doing is hard." I think is the phrase. I try to do the necessary research, background reading, start from the ground up before attempting to do anything. I still find that getting your hands in it, ie learning by doing, seems to help the process along. With all this being said, it sure is frustrating and the rewards come slowly. While I DO like instant gratification, I don't expect it. I do expect that the payoff, it terms of reward vs time spent is reasonable. As my available personal free time has been less and less lately, making sure that I'm not just wasting my time is important to me. Do you find that you spend most of your time on projects that are well within your knowledge and experience, or most of your time learning about new technology/skills/programming language/hardware/etc to facilitate accomplishing a new project? Thanks Keith

16 years, 1 month

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