terry2@ihlpm.UUCP (t. nelson) (10/30/85)
I use the Apple Access II software for my communication needs.
Up until recently those needs have only been to communicate
from home to the main-frame computer at work. When I want to
download a file into my apple, I open a recording file in Access
II and tell the main frame to concatenate (cat in UNIX) the file.
I am now exploring the world of Bulletin Boards. Most seem to
use various forms of data exchange protocol like XMODEM or
XMODEM/CRC. Access II uses Christensen (sp?) protocol. I have
been told that XMODEM and Christensen protocols are the same.
Is this true? What's the difference between XMODEM, XMODEM/CRC
and some other popular protocols? I have used Christensen protocol
between two Apples and it works fine (slow but fine).
Thanks in advance.
--
..ihnp4!ihlpm!terry2 =-=-=-=-=-=-=-=-=-=-=-=-=- "All this is
| Terry Nelson | because of me
Keep | AT&T Bell Laboratories | and not my
It | Naperville, Illinois | employer!"
Warm =-=-=-=-=-=-=-=-=-=-=-=-=- flaps@utcs.uucp (Alan J Rosenthal) (10/31/85)
In article <557@ihlpm.UUCP> terry2@ihlpm.UUCP (t. nelson) writes: >I am now exploring the world of Bulletin Boards. Most seem to >use various forms of data exchange protocol like XMODEM or >XMODEM/CRC. Access II uses Christensen (sp?) protocol. I have >been told that XMODEM and Christensen protocols are the same. >Is this true? What's the difference between XMODEM, XMODEM/CRC >and some other popular protocols? XMODEM describes how each individual block is sent. Ward Christensen is XMODEM protocol with a particular description of block 0, and the fact that the other blocks are data blocks. I will post a (technical) description of the protocol if requested. CRC stands for Cyclic Redundancy Check. It is a complex form of checksum. I would assume that XMODEM/CRC is just an XMODEM that outputs the CRC after transmission. Alan J Rosenthal {ihnp4|allegra|linus|decvax}!utzoo!utcs!flaps, cbosgd!utcs!flaps
spk256@uiucuxa.CSO.UIUC.EDU (11/01/85)
Ok, here it is: Ward Christensen wrote the XMODEM protocol with CRC checking...(Cyclic redundancy check), so that I beleive that all of the protocols you just mentioned are the same. Christiansen=XMODEM=XMODEM/CRC How's that? <<<<Whop!>>>> Benjy Mouse University of Illinois at Urbana-Champaign
jimv@apollo.uucp (James Vienneau) (11/06/85)
>>I am now exploring the world of Bulletin Boards. Most seem to >>use various forms of data exchange protocol like XMODEM or >>XMODEM/CRC. Access II uses Christensen (sp?) protocol. I have >>been told that XMODEM and Christensen protocols are the same. >>Is this true? What's the difference between XMODEM, XMODEM/CRC >>and some other popular protocols? >XMODEM describes how each individual block is sent. Ward Christensen >is XMODEM protocol with a particular description of block 0, and the >fact that the other blocks are data blocks. >I will post a (technical) description of the protocol if requested. I for one would be very interested in a technical discription/discussion of the transfer protocols. Since I have designed and built the hardware as well as written the driver for my serial port, I would like to take this the final step. Any help would be appreciated.