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101090 discussions

Using vintage computers in the classroom

by mark.kahrs＠gmail.com

The last time I taught assembly language programming, I decided to include the PDP-11 as an example of addressing modes. This is because Patterson and Hennesey just use MIPS --- it's a good pedagogical method but then when the students hit the real world they wouldn't know an address mode from ??? I also had them think about the VT-40 as an example --- I thought they would like that kind of graphical machine (I was wrong of course). If I was more prepared and had a full graphical simulator, that would have helped.

16 years, 1 month

SS50 to Exorbus adapter found

by chrise＠pobox.com

I was going through some boxes of parts for my SWTPC 6800 collection and I found an unpopulated PCB with SWTPC logo on it and date 1978 which appears to be an SS50 to Motorola Exorbus adapter. It has SS50 connectors on the bottom edge and the 43/86-pin Exorbus connector footprint on the top edge. Looks like locations for two DIPs, one 20-pin and one 8-pin, a voltage regulator and a few passives. The board is 8" wide by 2" high. I have no idea where this came from or why I have it. Does anyone know what it might be for? ie, does it adapt an Exorbus memory or peripheral to SS50 bus or does it adapt an Exorbus CPU to SS50?? I can send photos of the board to anyone that is interested. It appears to be an authentic SWTPC design/product rather than someone's homebrew project or a third party product. So, I am interested in learning more about it. Chris -- Chris Elmquist

16 years, 1 month

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

by dm561＠torfree.net

Date: Sun, 28 Mar 2010 18:00:33 +0100 From: Liam Proven <lproven at gmail.com> Subject: Re: Leaving computers on... (was Re: Disc analyser news update) On Sun, Mar 28, 2010 at 5:26 AM, Joost van de Griek <gyorpb at gmail.com> wrote: > On 26 March 2010 02:58, Liam Proven <lproven at gmail.com> wrote: > >> On Thu, Mar 25, 2010 at 7:42 PM, Josh Dersch <derschjo at mail.msu.edu> wrote: >> >>> I was thinking more of the battery in the original Mac Portable (which I >>> know is not what you're referring to). ?The portable weighed 16lbs, due in >>> no small part to the lead-acid battery it used. >> >> Yes, that was my guess, too. Only laptop-/style/ portable I ever even >> heard of with a lead-acid battery. > > PowerBook 100. Basically a repackaged Portable. --------------------------------------------------- The Sharp PC-5000 also had a lead-acid battery; according to them, L-A has a longer shelf life, charges faster, and is actually smaller and lighter for the same power than the NiCds of the day. mike

16 years, 1 month

Using vintage computers in the classroom

by lynchaj＠yahoo.com

> -----Original Message----- > From: cctalk-bounces at classiccmp.org > [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Michael Black > Sent: Sunday, March 28, 2010 4:28 PM > To: cctech at classiccmp.org > Subject: Using vintage computers in the classroom > > Hello cctech community, > > I am a computer science professor and an avid collector and restorer > of old computers, which I routinely use in my classes. (I am also a > long-time lurker on cctech, but haven't posted much yet, I'm afraid.) > I am interested in chatting with other professors and teachers who use > working demonstrations of vintage technology in their classes. I am > aware of many cases where professors have taught courses on computer > history, used pictures and simulations of vintage computers, or took > students on field trips to computer museums. However, I am > particularly interested in examples where professors bring actual > working vintage equipment into the classroom (like a pdp-11 or a > teletype machine) and tried to teach their students to operate it. > Has anybody on this list tried it or know of people who do it? > > Thanks, > Michael Black [AJL>] Hi! You are welcome to use the N8VEM project for educational purposes. I designed it with use in education as its primary purpose. It could be readily used to teach fundamental computer hardware and software principles in an easily illustrated manner. Starting with a blank sheet of paper and building up the basic conceptual elements in a process which results in a simple working microcomputer would be educational and highly entertaining. Add some devices like the ECB backplane and the ECB bus monitor and you can show the CPU operating in single step mode, the effects of reset, and all kinds of computer operation. The N8VEM SBC is simple and inexpensive enough that it can be built by beginners, as many are already, and normally works the first time. It works by itself interfacing to a serial port although it can be expanded to video boards, floppy and IDE disks, and even custom peripherals. http://n8vem-sbc.pbworks.com/ http://groups.google.com/group/n8vem I hope this helps. Thanks and have a nice day! Andrew Lynch

16 years, 1 month

Disc analyser news update

by classiccmp＠philpem.me.uk

Hi guys, Quick update regarding the disc analyser... Latest news is: * The USB interface is now running properly at full speed. Write-to-buffer has gone from 84Kbytes/sec to over 180 with two small firmware tweaks. Read speed is a little under 250Kbytes/sec, which means the entire 512K buffer can be read out in a shade over two seconds. It's not going to win me any awards, but I think it's plenty fast enough. * It Has A Name! One of my friends suggested "DiscFerret" partly as a slight dig at the Catweasel. The name has stuck to the point where I've... um... registered a .com domain name for it... (hey, it only cost ?12). I'll be setting up the site as soon as I find a nice Wiki package that isn't bloated to the size of a small main-sequence star (*koff* Mediawiki). * Schematics are basically done. I need to test the power supply section, which is on the to-do list for a bit later on. Soldering down the QFN-packaged power regulator IC will be interesting. * There's an external power output for disc drives. It provides +12V at 1.5A and +5V at 1.5A. Perfect for running small 3.5in drives, and saves a mains socket. Haven't decided on a connector, but the +12 is fed directly from the input power supply, so if you connect a 15V PSU you'll see 15V on the EPS output. * Power supply can accept between 9 and 15V, though it is specified to operate with peak efficiency at approx. 12V. Input is reverse-polarity protected with a grounded-gate low-Rds(on) MOSFET. I'll probably be building up a prototype power supply board tonight or tomorrow, and giving that a good beating with a homebrew DC load. I think I've got some MJE3055s and trimpots somewhere, though whether they'll work with Vce=1.2V remains to be seen (I suspect a MOSFET might work better). But first I need to get my paws on some 0.5mm carbide drill bits. There are a couple of vias on that board that are in a really tight spot... I make no secret of the fact that it was designed to be commercially manufactured, not haphazardly assembled by some semi-skilled engineering student in a garden shed (i.e. me!) The plan for those is to drill out the holes, push in a resistor leg flush with one side, solder on one side, cut and file flush on the other side, then solder that side too. I figure that should be a tight enough fit that the wire won't be going anywhere... and if that doesn't work there's always 26SWG tinned copper wire. Cheers, -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/

16 years, 1 month

cctalk Digest, Vol 79, Issue 56

by marvin＠west.net

From: Josh Dersch <derschjo at mail.msu.edu> > (As a related aside, is there *anywhere* one can get hard-sectored 5.25" > floppies these days?) People have been known to make their own 5 1/4" hard-sectored disks. I don't remember the details, but the basic idea was to take a 5 1/4" disk drive to hold the disk, make an index wheel for the holes, add a hole punch, and then just add time.

16 years, 1 month

Does a Northstar S-100 Bus Horizon Classify as a Classic

by acheel＠internode.on.net

Hi Dave, Interested to read about your Northstar S100 bus computer I have two of these withdual 51/4 disk drives sitting in my shed here in Adelaide South Australia I think I also have some manuals and software somewhere in the shed as well Are these of any value ? I also have some DEC desktop comuters and screens, disk units and tape units along with some operating software Kind regards Andy Cheel

16 years, 1 month

Probably offering TC11 controller

by hachti＠hachti.de

Hi folks, I'll most probably offer a TC11 controller for sale in the next days. The controller connects to a pdp11's Unibus and can handle up to eight TU55/TU56 tape transports (i.e. four TU56). It is configured for TU56 control levels ("integrated circuit"). Ebay would probably be the easiest way to handle a transaction with overseas buyers. Are there interested persons willing to pay nearly USD 150 for shipping? Regards, Philipp

16 years, 1 month

IBM Monochrome "Black and White" Parallel card double iimage

by billdeg＠degnanco.com

> This is certainly not a capacitor problem... > > I think this board uses 2144s as the video memory > So my first guess is to replace the RAMs. > > -tony > > ---- > > I'd be looking for a stuck address bit, or possibly a failed RAM chip > My money's on a 74xx chip (possibly a counter, buffer or multiplexer) > that's had an output fail open. > > Phil > > ----- > Along with Phil's suggestion of memory addressing issues resulting in a > double-scan of the memory, the staggering of the images suggests interlacing > might be occurring when it shouldn't be. Sometimes it is possible to tweak the > V/H-hold controls enough on monitors to end up with interlacing occurring when > it shouldn't. Can you discern whether each of the scan images contains a full > set of lines vs half the number of lines? > > I hate to ask, but what sort of monitor is this being displayed on? > IIRC the scan rate for MDA was higher than NTSC and I'm not not sure whether an > NTSC monitor would sync up or sync down to half the scan rate. > > Brent ----------------- Thanks for the feedback. I am using a standard IBM monochrome monitor. I tested the monitor with another known-working card, and I also tried another monitor. The problem is with the display card. 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! Bill Degnan

16 years, 1 month

Data I/O29A

by mdelepeleire＠hotmail.com

Hello, I cannot find doc informing how to send ie an .HEX file from Hyper terminal to my programmer, when the programmer sends a file to the cpu the format is a sort of a start character, the address of the first byte and then a series of : HH HH HH HH HH etc where H stands for a hex symbol. Do I need to translate the Intel Hex file or how can I send an OMF-51 file? Do I have to use another communication program?? Thanks if you can help me. Marc De Lepeleire _________________________________________________________________ Hotmail: Trusted email with Microsoft?s powerful SPAM protection. https://signup.live.com/signup.aspx?id=60969

16 years, 1 month

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