test-drb February 2016

test-drb@ccmp.vtda.org

203 participants
239 discussions

Help with getting an original Altai running: 8080A clock circuitry and MITS88 2-SIO board

by robo58＠optonline.net

Hi Folks, I'm looking for some insights in getting an original Altair running again. My buddy asked for my help getting his Altair running again. He went through and replaced all the electrolytic caps, cleaned up everything and then tried to get the MITS 88 2-SIO board to run a simple echo program. It wouldn't work and now I have the Altair, I've been looking it over for about a week and I've noticed the following. 1). The 2Mhz base oscillator circuit will not reliably start up when it's hot. It's perfect when cool. 2). The original MITS 2-phase clock circuit was modified. The 74123 was replaced with a 74221 along with RC changes. 3). The MITS 2-SIO card has two Motorola 6850 ACIA's that don't seem to do what their data sheets say they should be doing. Some questions for you. (I've searched for insights on these topics and information is scarce). a). Was the Altair known for hot start issue(s) ? If so are their tried and true fixes? b). Going to a 74221 appears to be an excellent move. The RC changes were prompted by that move. There is no longer an RC delay circuit from phase 0 to phase 1, which appears to make sense. I don't see one-shots as a wise clocking design choice but my buddy wants to stay with it. Are their tried and true fixes here? c). I hand assembled some code to exercise the 6850. I know it has a software reset and then you set attributes. I tried my buddies echo program. It looks for a received character and then echo's it. I'm using a laptop and PuTTy along with an RS-232 breakout box. I can see characters going in but nothing coming out. The 6850 appears to drive the bus for a finite amount of time and then turn off its drivers. I don't have any experience with the part and I don't know if that's the way it's supposed to work or that the Altair has a bus timing issue. Any thoughts on what I'm seeing and suggestions/fixes ? Thanks Robo

10 years, 1 month

Tired of EVERYTHING with a gear being called STEAMPUNK? Yikes I am...

by COURYHOUSE＠aol.com

I am very envious of the animators skills on those singing people in the still portraits.. Heh is there any easy way to do this? Ed# In a message dated 2/7/2016 1:13:03 P.M. US Mountain Standard Time, pete at dunnington.plus.com writes: On 07/02/2016 17:50, COURYHOUSE at aol.com wrote: > > Tired of EVERYTHING with a gear being called STEAMPUNK? Yikes I am... > This fun and creative video pretty much sums things up! > https://www.youtube.com/watch?v=TFCuE5rHbPA Epic! -- Pete

10 years, 1 month

Announcing TCP/IP for RSX-11M-PLUS

by bqt＠softjar.se

Well, about two weeks since my last announcement, but I figured I should do another one. I've cut a new release of TCP/IP for RSX, and I encourage everyone to update to this latest release. A short list of changes since my last release: Documentation: . I've worked some on the documentation, and filled out some parts that were previously TBD. TCP: . Performance improvements. In general, I've improved file transfer performance by about 20% by tuning when TCP ACK messages as well as window updates are sent. On links where packets are dropped from time to time, the performance improvements can be significantly higher. . Bugfix. Retry counter were incorrectly reset under some circumstances. . Bugfix. TCP did not resend an ACK if the same data was received twice. . Bugfix. TCP sockets could erronously be left in a closed state with no task. However, looking at the socket, it looked like a task was associated. FTP: . Size calculation for stream type files in RSX mode was done incorrectly. Applications: . I've included a precompiled version of PCL.TSK As usual, the distribution is available from: ftp://mim.update.uu.se/bqtcp.dsk ftp://mim.update.uu.se/bqtcp.tap ftp://ftp.update.uu.se/pub/pdp11/rsx/tcpip/tcpip.dsk The documentation is also available through ftp on Mim, or also at http://mim.update.uu.se/tcpipdoc Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

10 years, 1 month

Oddball floppies for trade - 8", HS (outer edge), weird cutout

by jwest＠classiccmp.org

I have two "flippy organizers" (that's around 20 floppies each) full of these oddball floppies. Picture at https://www.flickr.com/photos/131070638 at N02/22020178558/in/dateposted/ They are 8", hard sectored, and the sectors are on the outer edge rather than the hub, and there is an odd cutout on one edge that goes inside the drive. I know I don't have a machine that uses these, so they are available for trade. J

10 years, 1 month

Calibration of 8" floppy drive?

by james＠attfield.co.uk

> Date: Sat, 6 Feb 2016 00:46:33 -0500 > From: Dan K <100dashsix at gmail.com> > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Subject: Re: Calibration of 8" floppy drive? > Message-ID: > <CAAQ+N0XNG=NnWGRnt8oxN4WeXTuoLCXPO9BQRn9oaSjZfVNW > 5A at mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Are there any good alternative solutions I can do to replace it? I'm > sure I don't want the plastic touching the disk media. > > -Dan Seems like eons since I learned to align PerSci 299B's with Dysan alignment disks and 'cat's eyes' on a 'scope :) I echo the other sentiments here - do NOT undo or unscrew anything relating to head positions especially involving allen (hex) screws unless you have a 'scope, an alignment disk, a very good quality set of hex screwdrivers (keys will normally NOT suffice) and a modicum of experience. Granted, lead screw single-headers are a little easier to do than voice-coil double-headers but if you don't have to get into it then don't - explore all other options first. I'm afraid my TM-848's are double headers so the top head provides the pressure but back when the drives were single headed felt pads did the job of the second head. The tension was provided by the spring, the pad just prevented scoring. I do NOT speak from experience BUT if I had to use anything the kind of small felt pads you can get from hardware stores (e.g. B&Q in the UK) seem remarkably similar in composition and would be worth a try especially if you have one original to compare. Cut to shape, most are self-adhesive too - bonus. HTH James

10 years, 1 month

Farewell and thanks!

by snhirsch＠gmail.com

I've finally had my fill of the general grumpiness and bluntly worded interactions on this list. Over the years I have learned a lot and would like to particularly express my thanks to Tony Duell, Fred Cisin and Chuck Guzis for being unfailingly polite and very forthcoming with technical advice. --

10 years, 1 month

Mosaic 4.0 for openVMS

by rlloken＠telus.net

Gentlemen, I stumbled across a reference to Mosaic 4.0 for VMS dated 2006. I ran Mosaic on my VMS workstation around 1994 and had abandoned it long ago first for Netscape 3.0.3 and later for Seamonkey. I did not know that there was any development on Mosaic in recent decades I found Seamonkey to be glacially slow on AlphaServer 4100 "desktop" and so I have not attempted to do much web browsing on VMS in recent years. So... Is Mosaic 4.0 useful in 2016? Is it more useful than Seamonkey? Netscape? AFAIR, HP had a port of Firefox to IA64 VMS but not to Alpha, has anybody been so burdened with spare time that they have attempted to port firefox to Alpha or VAX VMS? Or any other web browser? I hope to attempt a port of the heritage version of nroff/troff to VMS some time in the next couple years (I think groff would be much more difficult). But that is a differant subject. -- Richard Loken VE6BSV, Systems Programmer - VMS : "...underneath those Athabasca University : tuques we wear, our Athabasca, Alberta Canada : heads are naked!" ** rlloken at telus.net ** : - Arthur Black

10 years, 1 month

Calibration of 8" floppy drive?

by 100dashsix＠gmail.com

I have two intermittently functional 8" floppy drives that I debugged to the best of my ability, and as far as I've been able to tell their problems must be limited to the circuitry that deals with the actual magnetic interface with the disk. The intercommunication seems normal and the head load solenoids fire, but after that the drive often aborts the process, presumably because it wasn't able to read data properly. I think the signal for reading the disk-rotation hole even fires correctly. The drives are Siemens FDD 100-8 drives used in an S-100 bus system, and controlled by a Jade "Double D" disk controller. The machine was in a functional state when stored, and I have known-good copies of disks that I've been able to boot from at least a few times. (Unless the drives somehow damaged them.) Can someone knowledgeable about 8" floppy drives share information about how these things were serviced and maintained, and what sort of procedures were required to test and calibrate them? Information I've picked up through osmosis leads me to believe that there's a floppy disk with a special pattern on it, and you use specialized test equipment to check the flux off the head and dial it into proper settings. I suspect there the drive has trim pots or similar that allow for this. So, how do you deal with your 8" drives, and what do you do when they don't work? Thanks, Dan

10 years, 1 month

emergency moderation mode RE: Virtualizing AIX 1.3 - WAS::::Re: AIX for IBM PS/2

by jwest＠classiccmp.org

I had already turned on emergency moderation mode to try and stem the tide of this escalating further. I had also already emailed a few people off-list about this, which is primarily how it should be handled. Those who should have been corrected... were. Quietly. I'm rather tired of (a very few) people commenting "oh, this list is so much smaller than other forums" or "there's such a low SNRatio here" or "Everyone here is unfriendly (or things like that)". Screw all of that. I submit that while this list may be small, it has the best content and expertise, far better than others (I've looked). I submit that while the SNRatio gets off track once in a great while, I've seen that happen elsewhere, and at least as often if not more. Perhaps some should use their technical expertise to study the function of the "delete" key. Quite frankly I don't think it happens here all that often. Unfriendly? Perhaps there are a few that are brisque at times. On the one hand - Guess what... that's life. In any crowd there's always a few grumpy old men (of which I am one - especially at the moment), and socially well-adjusted people should learn how to deal with it and get along. On the other hand - That doesn't mean I don't correct those that need correcting (and I did) .. but I really don't need to hear the whining. It seems that there are one or two people that state they don't want to participate because of one or more of the above... yet they stay here solely to voice that opinion. Odd. J

10 years, 1 month

IBM 5100 - APL Only Version on Ebay

by wayne.smith＠charter.net

There is an APL-only IBM 5100 up on Ebay. Had known that these were supposedly made, but have never seen one before. Looks a bit rough, but based on the pictures boots to the "CLEAR WS" screen. http://www.ebay.com/itm/Vintage-IBM-5100-Portable-Computer-Powers-On-/ 321999141713

10 years, 1 month

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test-drb February 2016