- vcf-midatlantic - lists.vcfed.org

FS: Leader LS-1020 20 MHz Analog Dual Trace Oscilloscope
by Systems Glitch 05 Jun '16

05 Jun '16

link: http://www.ebay.com/itm/272264264580 Simple 20 MHz analog dual trace oscilloscope. Fully tested with my Tektronix function generator. Picked it up in a lot of surplus lab gear. This would be a fine little 'scope if you need something to look at relatively slow digital signals or for general hobbyist level analog work. Thanks, Jonathan

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"bit rot" LCDs
by Jeffrey Jonas 05 Jun '16

05 Jun '16

Apropos of the pocket computer with the rotting screen: I have a parts drawer full of NOS unused LCDs. Some have gone dark and now it seems to be spreading. Does one out-gassing/leaking cause the others to rot? Some even had silicone sealant along the edges! -- jeffj

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FS: Tektronix/Sony 308 Data Analyzer (Logic Analyzer)
by Systems Glitch 05 Jun '16

05 Jun '16

link: http://www.ebay.com/itm/272264216556 Fully functional, just selling it as I've finally got my HP 1650A logic analyzer set up and checked out. I've used this little logic analyzer a number of times in both vintage computer and embedded microcontroller work. It comes with the P6451 pod, which allows both 8-bit parallel data acquisition and serial analysis. Full flying lead and grabber kit included -- you can plug the flying leads onto AP/3M "DIP clips", standard pin headers (like an IDE header), wire wrap pins, or into the grabbers. Instruction manual is included, as well as an IEC power cable and the protective front panel cover. This unit can be expanded with a word recognizer pod, which allows input from 16 possible inputs to trigger data collection. This can be used to trigger when, for example, an 8-bit CPU hits a certain address. The auction does *not* include a word recognizer pod. As with all listings, if you'd like to save on shipping by having me bring this to the next VCF workshop event I'm able to attend, that's fine! Thanks, Jonathan

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Video Footage from VCFE XI
by Douglas Crawford 04 Jun '16

04 Jun '16

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Looking for Compaq DeskPro/386 parts
by Richard Cini 04 Jun '16

04 Jun '16

All – This old Compaq DeskPro I dug-out is working great at this point, and I located a second Type 17 MPI/CDC hard drive. However, I am looking for a few random parts for it. If anyone has the following that they’re willing to part with, please contact me off-list: · Drive power cable (5-pin black on the mobo side and regular 4-pin drive on the other; gray wire). Right now I’m using a power splitter which works fine. Just looking for OEM cable. · Drive mounting slides (2). These are solid metal, maybe 3/16” thick and have holes drilled for both the drive and the cage. None of the slides I have are thick enough. · Keyboard and/or cable. The cable on mine is shot and the SPACE bar doesn’t work. I’m using a regular AT keyboard, which of course works fine. The mounting slides is the most important right now because I can’t find a way to secure the drive properly. I also located a generic ‘286 motherboard for my rusty non-booting AT. Got it cheap, so it was worth buying it for testing versus the original AT board. Hopefully between the two machines I’ll be able to get a Windows 1 demo working. Thanks! Rich -- Rich Cini http://www.classiccmp.org/cini http://www.classiccmp.org/altair32

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IMPORTANT Info - Workshop June 11/12
by Jeffrey Brace 04 Jun '16

04 Jun '16

LOCATION: InfoAge Building 9032A - (2201 Marconi Road, Wall Township, NJ) TIME: Start about 10 A.M. on Saturday and ends whenever we go to sleep. End about 5 P.M. on Sunday. (Starts around 10 A.M. Sunday morning) COST: $10 for all members attending the workshop, which VCF donates to InfoAge as thanks for providing the space for us. EQUIPMENT: VCF will provide a table and you can use any available electrical outlet. Bring your own tools, power strips, power cords and supplies etc. DRINKS: You should bring your own. I would recommend bringing a cooler of some type. Upon request there is a refrigerator available down the hall. FOOD: You provide your own. We may order pizza or go out to a dinner. Usually we make a decision when everyone gets hungry. GATE: Please close the front gate behind you. We want museum visitors to go to the front lobby and not wander through the middle of the campus. PARKING: Park behind the back ramp of 9032A (which is around the building), or in the main parking lot, NOT in the courtyard. QUESTIONS? Please ask me (Jeff Brace) or Evan. My cell is 732-759-1783 and Evan’s is 646-546-9999 in case you need to contact us. See everyone there! And have fun!

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My ebay score :)
by Evan Koblentz 04 Jun '16

04 Jun '16

It's in transit, so I guess that's good enough .... I bought a four-volume set of Army books about (ahem) automatic data processing for a grand total of ten dollars. I viewed/copied some individual pages of the first three books while doing research at the old Ft. Monmouth museum several years ago. Didn't know there was a fourth book and they're not available on Amazon or used.addall.net or anyplace else. The volumes are: Book 1 - Introduction to ADPS Book 2 - Army use of ADPS Book 3 - Fieldata equipment Book 4 - Fieldata system application I'll loan these to the museum and put them on display with our MOBIDIC/Fieldata exhibit. But first, I will scan them and make them available to Bitsavers/Archive.org.

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Re: [vcf-midatlantic] June 11/12 Workshop - Who's Going? Whatcha working on?
by Todd George 04 Jun '16

04 Jun '16

01-Jeff Brace-Commodore 64 Robotics Kit for HOPE Exhibit 02-Evan Koblentz-Lego LOGO robotics kit for HOPE exhibit (Apple II, IBM PC) 03-Alex Jacocks-PS/2 model 70 and AT&T 6300 testing/repairs (Sunday) 04-Dean Notarnicola - TRS-80 Model 4, Model 4D, Model I 05-Todd George - Not entirely sure, but definitely will bring my AT&T 6300 as well! (I think the highest number was 5... ???) I have an AT&T 6300 with monochrome and color monitors. Monochrome jobby works, color is broken. I've already located and replaced a few bad components, can't seem to get the CRT to come totally alive though. The 6300 works (or worked) when I tested it last. I didn't think anyone else would be bringing them but seeing as Alex is interested, I'll bring mine!! Olivetti/AT&T party!!! WOOT!!! Other than that, I'll probably bring whatever else I'm actively working on by then. As far as current projects, that's going to be a Commodore SX-64, a TRS-80 Model 4P, or a Commodore VIC-20. If I'm a real glutton for punishment, I might bring my Macintosh Color Classic that has had me stumped for months now. Additionally, I'll have my EEPROM burning machine w/some blanks, various parts, and tools including a desoldering iron. I'll also bring a nice oscilloscope. Looking forward to it! -Todd

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hard drive and floppy disk emulator
by Rolf Levenbach 04 Jun '16

04 Jun '16

A MFM & RLL hard drive and floppy disk emulator on eBay: http://www.ebay.ca/itm/-/301968006996 Rolf

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Good source for eproms?
by Herb Johnson 04 Jun '16

04 Jun '16

My comments and questions. Dave McGuire posted: > They can be erased with X-rays. EPROMs were originally designed to be > erased that way. There are problems with that approach, however. (hence > the move to UV). The notion that one can plop non-quartz PROMs under an X-ray and erase them, has been mentioned here, and elsewhere for decades, as a "could be done". But I'm not aware this has been, or is, any sort of common practice, much less an established procedure. I'm aware of 'theory', I know physics. I'm talking accepted practice. Wikipedia....EPROM...citation 6...is a May 10 1971 article from Electonics Magazine by Dov Frohman, who apparently "invented the EPROM". Google..... http://www.jmargolin.com/patents/eprom.htm references the article, and interviews the author later in 1993. The text say Intel shipped that 1702 EPROM "with a window because X-rays ....disrupted the structure" of the chip. The Web page has some details. I"ve not (yet) read the article, or checked the patent. This suggests that X-rays were not a production nor a customer practice. so: Can you cite a reference I can find also, that shows a product announcement, or a production data sheet, that says specifically that a customer can erase a specific PROM product using X-rays of a particular wavelength and energy for a particular period of time? That's how UV exposure is cited (when it was cited in detail) in data sheets. I'll grant the possibility this occurred for some very early product, some early development in the semiconductor lab, or some military or other specialized application. I'll grant some hackers could borrow a dental X-ray and erase an EPROM - did they do subsequent life-tests? Even that description would be of interest. Thank you. Herb Johnson -- Herbert R. Johnson, New Jersey USA http://www.retrotechnology.com OR .net

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Personal ebay score
by Evan Koblentz 04 Jun '16

04 Jun '16

Yesterday I was poking around ebay. Stumbled onto something awesome and it only cost me twelve dollars. I'm a very happy camper. :) Will reveal it when it's in my possession... < insert diabolical laughter >

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HP 1650/1651 Logic Analyzer Disk Images
by Herb Johnson 03 Jun '16

03 Jun '16

http://www.retrotechnology.com/herbs_stuff/386intel/beech_logic.html I have a 1650B, and my Web site shows my colleague Bill Beech and his use of a 1650B on S-100 systems. He'll appreciate that Z80 disassembler, thanks. Herb -- Herbert R. Johnson, New Jersey USA http://www.retrotechnology.com OR .net preservation of 1970's computing email: hjohnson AAT retrotechnology DOTT com alternate: herbjohnson ATT retrotechnology DOTT info

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HP 1650/1651 Logic Analyzer Disk Images
by Systems Glitch 03 Jun '16

03 Jun '16

I picked up a HP 1650A Logic Analyzer at a surplus auction a few months ago, and finally got around to imaging the disks. In addition to the OS and demo disks, I have what is apparently a somewhat rare/sought after copy of the Z80 Inverse Assembler. This lets you disassemble Z80 code right in the logic analyzer. All images were captured with Dave Dunfield's ImageDisk. I've uploaded them here: http://filedump.glitchwrks.com/software/hp_1650/ You should be able to write them out with ImageDisk on a DOS PC with a regular 1.44 MB PC floppy drive. They're double density disks of course. If you have one of these analyzers and can't write disks for some reason, PM me and I can probably mail you some. Thanks, Jonathan

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Repair TRS-80 pocket computer screen
by Christopher Blackmon 02 Jun '16

02 Jun '16

Does anyone know how to repair/replace the screen on a TRS-80 pocket computer? It looks like the edges of the screen are bleeding ink or something. Christopher.

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Re: [vcf-midatlantic] Repair TRS-80 pocket computer screen
by Jonathan Gevaryahu 02 Jun '16

02 Jun '16

Bleeding 'ink', like a black ring which is converging toward the center of the lcd? or squiggly lines of black 'ink' coming from one edge? In either case that's irrepairable, you're going to need a replacement lcd for that. -- Jonathan Gevaryahu jgevaryahu(a)gmail.com jgevaryahu(a)hotmail.com

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TEI MCS-CPU 8080 CPU Board
by Herb Johnson 02 Jun '16

02 Jun '16

Bill Degnan wrote: > I wonder if this is the board Roger Amidon wrote the Apple Monitor for? No, he wrote it for the MITS Altair he bought. Roger said so, in a panel at VCF-East some years ago. You may be confusing "TDL" with "TEI". For TEI docs, I only have docs for the mainframe. Jonathan AKA System Glitch wrote: > I noticed that the layout of the basic CPU function (excluding the add-ons) > is *very* similar to the IMSAI MPU-A. Your Web page is a good examination. It notes even board-trace similarities. It's likely TEI copied the IMSAI and then added their own features. Lots of copying went on in the S-100 era, down to replicating boards completely. If it's that similar, then producing a schematic may be a matter of verifying the board with ohmmeter following (and correcting) the MPU-A schematic. Herb -- Herbert R. Johnson, New Jersey USA http://www.retrotechnology.com OR .net

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Workbench from hell
by Mike Loewen 02 Jun '16

02 Jun '16

Dave McGuire, someone snuck into your shop. :-) https://hackadaycom.files.wordpress.com/2016/05/williams-workbench.jpg Mike Loewen mloewen(a)cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/

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Workbench from hell
by Herb Johnson 02 Jun '16

02 Jun '16

Actual facts about the bench and person in question: http://www.computerhistory.org/atchm/an-analog-life-remembering-jim-william… https://www.flickr.com/photos/mightyohm/6780036836/in/album-721576294448252… "Workmates respected Jim's privacy and would never dream of taking something from his workspace, in part fostered by Jim's desire to make his workspace look as uninviting as possible." - from the exhibit Herb Johnson -- Herbert R. Johnson, New Jersey USA http://www.retrotechnology.com OR .net

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OT?: PCMCIA Network cards
by Kelly Leavitt 01 Jun '16

01 Jun '16

Anyone need these? I've a drawer full of miscellaneous ones. Will bring next time if anyone wants. 3Com and DLink mostly. Kelly

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Jim Williams' lab
by Jack Rubin 01 Jun '16

01 Jun '16

That ain't messy, that's ANALOGUE!!

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We're getting a CompuPro
by Evan Koblentz 01 Jun '16

01 Jun '16

There is a nice donation arriving in a couple of weeks. As described by the owner: "Godbout CompuPro S-100 bus CP/M-80 microcomputer with dual 8" floppy disc drives, quite a few discs with software, some docs, a Hazeltine Esprit CRT/keyboard terminal, and Xerox Diablo daisy-wheel printer" This is a historic system and I remember Herb showed one a few VCF Easts ago.

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TEI MCS-CPU 8080 CPU Board
by Systems Glitch 01 Jun '16

01 Jun '16

I picked up a TEI MCS-CPU from Jeff Galinat at VCF East XI this year. It's an 8080 CPU board with onboard power-on jump, power-on reset, and MWRITE generation. Jeff didn't have any documentation on it, and I've been unable to find any online, other than mentions in sales literature. I took a little time tonight to go through it, figure out the onboard functions, and get it fully operational: http://www.glitchwrks.com/2016/05/31/tei-8080-cpu Neat little board, though TEI expected you to use the extra features (power-on jump, power-on reset, and MWRITE) in an all-or-nothing fashion: jumper J1 enables or disables everything. I wanted power-on jump and power-on reset, but didn't need MWRITE since I was using a front panel with it, so the writeup includes the trace cut modification I used to disable it. There are convenient vias on either side of the cut, so you can add in socket pins for a removable jumper. The writeup also documents the function of the switches for setting the power-on jump address. As I was working on this board, I noticed that the layout of the basic CPU function (excluding the add-ons) is *very* similar to the IMSAI MPU-A. Can anyone comment on this? Thanks, Jonathan

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Old Apple & other Computers - Free
by Greg Acker 01 Jun '16

01 Jun '16

I am moving west and have more old computers than I can take with me. If anyone wants old Apple Macs , SE, Performa, etc, a IIGS, and some Commodore 64 & other stuff free, call me at 724-992-4302. I need rid of it this week and I don’t want to toss it. Please come and rescue it. Greg Acker Merce, PA

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IEEE coverage
by Evan Koblentz 31 May '16

31 May '16

Remember this online Spectrum article from VCF East last month? http://spectrum.ieee.org/tech-talk/geek-life/history/theyre-alive-vintage-c… I'm told it is in the current print edition, too. Cool!

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Wish me luck
by Connor Krukosky 31 May '16

31 May '16

I'm currently packing to drive up to Poughkeepsie today, I start at IBM tomorrow. Wish me luck! I'll try to make it to next weekend's workshop I will be in Boston all of next week for a conference so hopefully I have some down time, also maybe me and Ian can carpool :) -Connor Krukosky

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WTB: MOS6560 / VIC Chip or Parts VIC-20
by Todd George 31 May '16

31 May '16

Need a MOS6560 to replace a defective one in a VIC-20. Additionally would consider a parts/ugly VIC-20 with a 6560 that has a fighting chance of working. I can desolder and all that. I've seen the dealer on eBay and am choosing to spend my money elsewhere (in the community). Hit me up off-list if you can help. :-) -Todd

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Homebrew 8080 machine in NJ
by Mike Loewen 30 May '16

30 May '16

This might be an interesting project for someone: Ebay #322128736174 Mike Loewen mloewen(a)cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/

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OT: cyber insurance
by Evan Koblentz 29 May '16

29 May '16

A question for my daytime job: anyone here work for a company that purchased cyber insurance? If so, then send me a private response.

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Anyone wanna go to Finland?
by Evan Koblentz 29 May '16

29 May '16

http://suomentietokonemuseo.fi/ Seems they're having an old computer fair in January.

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PC/AT power-good troubleshooting
by Richard Cini 28 May '16

28 May '16

All – I pulled my old PC/AT off the shelf to see if I could get Windows 1 running on it. It worked when shelved years ago, but it unfortunately suffered some case damage from a leaky battery. No damage to the mobo or cards thankfully. I replaced the battery with a 4-AA pack. Basically, the PC won’t come out of reset. I tested the power supply with a load tester specifically for PC power supplies and it reports power_good and all voltages look good on a meter. So far, so good. I dug out my ISA POST diagnostics card which also has a PG tester in it. This reports no_PG but I do see the reset pulse. Not sure why one would report OK and one not. I traced the PG signal from the power supply through the 82284 clock driver/ready interface chip and the PG is definitely there (transitioning L->H on power-on) and RESET is transitioning H->L. I have a spare power supply (which also tests good) and produces the same result. I have no cards installed, nor any other load on the supply (floppy and hard drives disconnected), so it purely has to be an issue with the motherboard. Any recommendations on where to go from here? Does anyone have an extra AT motherboard they would be willing to part with? Thanks! Rich -- Rich Cini http://www.classiccmp.org/cini http://www.classiccmp.org/altair32

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50 seconds in...
by william degnan 28 May '16

28 May '16

https://www.youtube.com/watch?v=j2VipiNWMWQ -- @ BillDeg: Web: vintagecomputer.net Twitter: @billdeg <https://twitter.com/billdeg> Youtube: @billdeg <https://www.youtube.com/user/billdeg> Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>

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VCF East Kenbak lecture (and bonus!) are now online
by Evan Koblentz 28 May '16

28 May '16

John Blankenbaker's speech from VCF East last month is now on YouTube: https://www.youtube.com/watch?v=OUCJXyThSXI Bonus material! Here's John (with Corey) examining the machine: https://www.youtube.com/watch?v=PDCKNDitH38

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(no subject)
by Mike Willegal 28 May '16

28 May '16

Not too many years ago, a friend found a Cray 1 that was stored in someone's garage and made a deal to buy it. Before he even took possession, he ended up trading it for an Apple 1 when he realized he didn't have a place to keep it. Who knows, there could be a few more out there in the wild. Not so many years ago, it was estimated that there were only 30 Apple 1 's remaining. New units keep surfacing every year. Regards, Mike Willegal

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Flashback Friday....
by Ethan 28 May '16

28 May '16

The encyclopedia commercials... The Apple II version: https://www.youtube.com/watch?v=lMpgcz6s-eI The DOS PC version: https://www.youtube.com/watch?v=Hxwin9XFbnQ The Amiga 2000 version: https://www.youtube.com/watch?v=ZuwbDRdCVs0

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Re: [vcf-midatlantic] Windows 1.04 SDK running in Bochs
by Blatboy 27 May '16

27 May '16

Sorry for the delay on my response here... but I was glad to be of assistance, and it was great meeting everyone! w ---- http://www.jwalterhawkes.com http://www.blatboy.com like to know where/when I'm playing? Click here <http://www.blatomaster.com/mlist.php> to sign up for my list, and let the babble begin. ------------------------------ Message: 3 > Date: Sat, 21 May 2016 18:16:59 -0400 > From: Richard Cini <rich.cini(a)verizon.net> > To: VCF-Midatlantic > <vcf-midatlantic(a)lists.vintagecomputerfederation.org> > Subject: Re: [vcf-midatlantic] Windows 1.04 SDK running in Bochs > Message-ID: <5CA0477C-B976-44D4-BA36-7B6D11AE3002(a)verizon.net> > Content-Type: text/plain; charset="UTF-8" > I should add that a huge thanks should go to Ron, Jason and Walter working > the hand-off. The materials were in a copy box, so not light by any stretch > of the imagination. Thanks guys! A great piece of history saved! > > > Rich

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The Transistor......Re: Evan @ IFIP
by Dan Roganti 27 May '16

27 May '16

On Thu, May 26, 2016 at 9:45 PM, Evan Koblentz via vcf-midatlantic < vcf-midatlantic(a)lists.vintagecomputerfederation.org> wrote: > They took us on a private tour of the old Bell Labs (now it's Nokia, which > bought Alcatel-Lucent) in Murray Hill NJ today. We spent a couple of hours > there. Photos were not allowed. Among many highlights, we saw the room > where they perfected (not "invented") the transistor > I bet you didn't say that _while_ you were visiting there :) And I would hardly call it perfected. As most academics often overlook the technical aspects. Where the 1925 FET is a voltage operated device whereas the Bell Labs Transistor is a current operated device. Two completely different animals Also, you how many of the innovations occurred in the past A lot of it was based on popularity, just look at Edison/Telsa And the 1925 FET was hardly on anyone's "radar" otherwise why did they spend the next 30yrs with vacuum tube computers iso of researching and developing that new innovation further. But it also had mostly to do with making the planar process practical enough to mass produce. Dan

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Robots and Relays and Commodore
by Chris Fala 27 May '16

27 May '16

Would this help? http://www.ebay.com/itm/152084733487

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Evan @ IFIP
by Evan Koblentz 27 May '16

27 May '16

Forgot to mention this. Tomorrow I'll be part of a roundtable discussion at an NYC meeting of the International Federation of Information Processing's history .SIG. I have 15 minutes to talk about early British mobile computers. Going to focus on Husky (which should be famous but isn't) and Psion (which needn't be famous but is).

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semi-OT: downloading vintage computer document
by Dan Roganti 27 May '16

27 May '16

anyone have some tricks up their sleeve to extract the pdf from this link ? it appears to be hiding behind a java servlet a site search falls into the same trap this might interest some of you too http://www.osti.gov/scitech/servlets/purl/5054065

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Good source for eproms?
by Jason Perkins 26 May '16

26 May '16

I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one. What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom. Thanks, -- Jason Perkins

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First Hollywood stops using paper tape in the film editing machines...
by Corey Cohen 26 May '16

26 May '16

And now that the pentagon is getting rid of 8" floppy disks by the end of 2017, without the military needing replacements, I bet this is the end of newly manufactured 8" floppies. I better get used to baking my old floppies for reuse. https://www.yahoo.com/news/us-nuclear-force-still-using-floppy-disks-report… Cheers, Corey corey cohen uǝɥoɔ ʎǝɹoɔ

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MOnSter 6502 Project - Microprocessor in Discrete Components
by Todd George 25 May '16

25 May '16

Saw this on Reddit, completely amazed... http://tubetime.us/?p=346 I am familiar with their 555 Timer IC project, and saw that they had a follow up project with the 741. Had no idea they'd take it this far. :) -Todd

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ADTPro help
by Evan Koblentz 25 May '16

25 May '16

I last used ADTPro about a year ago. It worked fine. A few months ago I installed a new mobo/memory/processor in my daily PC (still running Ubuntu). Yesterday I tried ADTPro again and got this error message: "There are no serial ports, or the serial library RXTX is not installed or visible." Paul H. suggested that the adtpro.sh file was looking in the wrong place for RXTX. Made some tweaks but it's still not working. Note also that ADTPro has its own copy of RXTX in a subfolder. Stephen E. also tried to help. Can someone who is experienced at both ADTPro and Linux (and who has the patience to walk me through this) help me, please? Hoping to get some help via telephone or Skype today/tonight if possible.

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Re: [vcf-midatlantic] Good source for eproms?
by Jonathan Gevaryahu 25 May '16

25 May '16

On 5/25/2016 10:29 AM, Bill Sudbrink via vcf-midatlantic wrote: > chrisjpf33 wrote: >> Is "metric assload" am official Department of Weights and Measures unit >> of measurement? > Actually, the proper SI unit is "metric buttload". > > Bill S. > > > Is assload a unit of volume, and fuckton a unit of mass? -- Jonathan Gevaryahu jgevaryahu(a)gmail.com jgevaryahu(a)hotmail.com

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Re: [vcf-midatlantic] Good source for eproms?
by Chris Fala 25 May '16

25 May '16

Thanks for clearing that up. I wasn't sure which was official and which was informal. I thought it was the rated PG vs. rated R. On Wed, May 25, 2016 at 10:29 AM, Bill Sudbrink via vcf-midatlantic < vcf-midatlantic(a)lists.vintagecomputerfederation.org> wrote: > chrisjpf33 wrote: > > Is "metric assload" am official Department of Weights and Measures unit > > of measurement? > > Actually, the proper SI unit is "metric buttload". > > Bill S. > > >

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A more efficient BBS Xfer protocol
by John Heritage 25 May '16

25 May '16

Hi folks! Being a geek and SysOp I spent a lot of time as a teenager looking for the most efficient BBS file transfer protocol - working through XModem CRC, Ymodem-1K, ZModem, ZModem with MobyTurbo, Ymodem-G, etc.. I even ran HS-Link (and BiModem) for a while to help people who actually uploaded to BBSes :). In search of CPS, the fastest I could transmit a compressed file over a 14.4 kbps link (1800 cps theoretical maximum) was using Ymodem-G** with a series of modem settings (AT&K0 - disable compression, and a few others), achieving just over 1730 cps. ZModem* was something in the 1630-1650 range, and DSZ's "mobyturbo" Zmodem would do ~ 1660-1665. Anyway I had an idea at the time to write a protocol that would dedicate 100% of the senders bandwidth to transmitting data while still adding error correction. Here's how it would work: 1. Sender streams data continuously; but calculates a CRC every X bytes (x=1024 initially), and stores to RAM. 2. Receiver receives data continuously; calculates a CRC every 1024 bytes and then sends back to the receiver over the modem back channel***. 3. Sender looks at CRCs received and if there's a match, continues sending. If there is a bad CRC, the Sender would either end the transfer (like Ymodem-G) or initiate some kind of "resume from previous bytes" control sequence TBD. 4. To help the file transfer end with minimum wasted overhead, I'd probably start the protocol with a simple string indicating how many bytes are in the transfer so the receiver knows when to stop recording. I know there's more to it than this -- the control sequence would still cost something unless I went the Ymodem-G route. The receiver would have to be fast enough to write to disk, calculate CRCs, and send CRCs without running out of modem buffer to prevent delays.. Anyway, in my mind this is 100% or as near to 100% efficient for a one-way file transfer as you can get.. Did anyone ever write a protocol like this? Am I a fool? :) Thanks! John ....... If you like reading: * Zmodem of course could resume and recover where Ymodem-G couldn't, but was less efficient due to certain control byte characters needing to be double sent when they appeared in the stream. ** Ymodem-G though rarely failed on "modern" error correcting modems.. *** USRobotics initial 14.4kbps implementation only had a 450 baud back channel which was limiting, but the industry standard (V.32bis?) was capable of 14.4kbps symmetrically.

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Workshop 6/11 & 6/12 - Who's going so far
by Jeffrey Brace 25 May '16

25 May '16

01 - Jeff Brace - Commodore 64 Robotics Kit for HOPE Exhibit 02 - Evan Koblentz - Lego LOGO robotics kit for HOPE exhibit (Apple II, IBM PC) 03 - Alex Jacocks - PS/2 model 70 and AT&T 6300 testing/repairs (Sunday) 04 - Dean Notarnicola - TRS-80 Model 4, Model 4D, Model I 05 - Jeff Jonas - ??? - (Saturday)

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June 11/12 Workshop - Who's Going? Whatcha working on?
by Jeffrey Brace 25 May '16

25 May '16

01-Jeff Brace-Commodore 64 Robotics Kit for HOPE Exhibit 02-Evan Koblentz- 03- 04- 05- 06- 07- 08- 09- 10- 11-

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Apple II Turtle Logo on Ebay.
by william degnan 25 May '16

25 May '16

Ebay 222124483812 "Logo" Turtle Graphics Programming Software and Manuals I seem to remember Mouse or Ian wanted this program (?), and that it was hard to find. Well here you go. b -- @ BillDeg: Web: vintagecomputer.net Twitter: @billdeg <https://twitter.com/billdeg> Youtube: @billdeg <https://www.youtube.com/user/billdeg> Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>

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Great article on Connor Krukosky
by Christian Liendo 24 May '16

24 May '16

http://www.ibmsystemsmag.com/mainframe/stoprun/Stop-Run/Connor-Krukosky/

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