- vcf-midatlantic - lists.vcfed.org

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.

1 0

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)

1 0

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-

6 10

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>

1 0

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

24 May '16

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

1 0

Re: [vcf-midatlantic] ADTPro help
by Kelly Leavitt 24 May '16

24 May '16

On May 24, at 2:48 PM David Ryskalcyk wrote: > On May 24, 2016, at 2:39 PM, Kelly Leavitt via vcf-midatlantic <vcf-midatlantic(a)lists.vintagecomputerfederation.org> wrote: > > > > Win10 x64 and Mint x64 both. This was with a prolific usb to serial adapter on an older i7 machine and the same on an i5 dell laptop running Linux. > It's possible you have a counterfeit Prolific USB-serial adapter. Does it work with the latest Prolific drivers on Windows 10? The older fakes would produce a "Code 10" error; the newer ones may not. > >I've had success with FTDI and Silicon Labs, as well as genuine Prolific adapters, but the fakes are of varying quality and don't always work. It's a real one. This adapter works everywhere, it only seems to have problems with the Java lib. I use this in everything from Windows XP to my Rasperry PI. I purchased a dozen for the local radio club and still have a couple of my own. I used the same adapter several years ago with the same setup and didn't have this problem. This was under Windows 7 back when ADTPro was only verified to work under java32. Kelly

2 1

Re: [vcf-midatlantic] ADTPro help
by Evan Koblentz 24 May '16

24 May '16

>> I saw a note where ADTPro gets upset if the serial port is missing (you should >> see something from the dmesg command). > > Is your user account a member of the "dialout" group? It not, you will need to use sudo to access serial ports on Linux. > > David I'm not sure how to check, but my account = admin, so it should have full privileges to everything. Anyway I tried running adtpro as sudo from a terminal and got the same error.

2 1

June workshop prize
by Evan Koblentz 24 May '16

24 May '16

My girlfriend handed me a bag today. She said it has a special prize inside for the first-to-smoke winner at the June workshop. Your guess is as good as mine!

3 3

Re: [vcf-midatlantic] ADTPro help
by Neil Cherry 24 May '16

24 May '16

On 05/24/2016 01:42 PM, Evan Koblentz wrote: >> Chris is correct Java cares about 64 and 32 bit os libraries. >> >> Evan do a" >> uname -a >> java -version > > Output: > > Linux evan-desktop 3.13.0-86-generic #131-Ubuntu SMP Thu May 12 23:32:41 UTC 2016 i686 > athlon i686 GNU/Linux > > Okay Linux is 32 bit, so it wants 32 bit libraries. Still need the java version: java -version What type of serial port are you using the PC's builtin serial, a usb serial or something else ? I saw a note where ADTPro gets upset if the serial port is missing (you should see something from the dmesg command). -- Linux Home Automation Neil Cherry ncherry(a)linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies

1 0

Re: [vcf-midatlantic] June 11/12 Workshop - Who's Going? Whatcha working on?
by Brian L. Stuart 24 May '16

24 May '16

On Tue, 5/24/16, Dan Roganti via vcf-midatlantic <vcf-midatlantic(a)lists.vintagecomputerfederation.org> wrote: > oh hey, I almost forgot, I still have the SVI-2000 robot arm if you want > something else for the HOPE exhibit or the NYC MakerFaire. > http://www.theoldrobots.com/images58/Robotarm-w1.JPG Now there's a blast from the past. Over 20 years ago there was a variant on that unit that had an RS-232 interface in the base. I got a loaner for a summer course I was doing. We drove it with a network of Sun workstations and had it playing Connect-4. Here's a little SIGCSE paper on the project: http://www.cs.drexel.edu/~bls96/robotics/p41-stuart.pdf BLS

1 0