papa@pollux.usc.edu (Marco Papa) (03/21/88)
In article <2955@gryphon.CTS.COM| bilbo@pnet02.cts.com (Bill Daggett) writes: |Hard Drive Down Memory Lane For Amiga! |back set for XMODEM-Checksum. I once tried Downloading from P-net set to |Kermit and me set to XMODEM and the transfer failed to get started. I |believe now that XMODEM-Checksum and XMODEM-CRC are incompatible but don't |tell you so during the whole transfer process. NOT TRUE. XMODEM-checksum and XMODEM-CRC are completely compatible. The receiver decides what he wants and an XMODEM-CRC started transfer with drop down to Xmodem-Checksum after a few seconds if the correct acknowledgement is not received. In fact X/Y/ZMODEM are also compatible ZMODEM ----| YMODEM -----| XMODEM-CRC -----| XMODEM-Checksum |I went back to P-net and |set its default to XMODEM-Checksum. I believe that files inside the ARCed |files even though they appeared outwardly to look intact were somehow |changed. Maybe they are tagged temporarily with the CRC checksum and ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |since I received them with vanilla XMODEM these checksums were not removed |or detected. NO. Both checksum (1-byte) and CRC (2-bytes) are NEVER stored with the file, just sent out over the serial line at the end of each block. |Perhaps a Hacker or two will read all this and confirm, deny, or offer up |something concerning this adventure? |What protocol, if I have the option, should I be using now days? Stick |with XMODEM, XMODEM-CRC, KERMIT or what? I guess the main thrust of this |question is should I get away from using old XMODEM? XMODEM (just like |ARC) is tried and true if used correctly - Grin! XMODEM is still the most widely used. It has a lot of problems when used with packet switching networks and when there is a lot of noise. It also does not trasfer the file intact, but pads it with NULLs at the end. YMODEM and ZMODEM fix these problems. Kermit is NECESSARY when sending binary files over 7-bit lines and it is also available ALMOST for any compyter on earcth :-) Neither of the X/Y/ZMODEM protocols supports 7-bit lines, though ZMODEM provides protocol expansion for it and will support it sometime in the future. -- Marco
john13@garfield.UUCP (John Russell) (03/24/88)
In article <8633@g.ms.uky.edu> sean@ms.uky.edu (Sean Casey) writes:
]
][regarding hard drive problems that probably originate with ARC]
]
]I have since started using "zoo", which has a higher compression ratio,
]supports long filenames, can archive directory trees, and supports better
]archive manipulation. If zoo runs out of memory, it simply complains and
]exits, and it will let you interrupt it at any time with a ^C.
Zoo can also be made resident in shared mode, by REZ. You can run multiple
copies at once, with memory overhead of 30K (executable) + 30K workspace
per copy instead of a flat 60K per copy. I can see some major advantages there!
Arc can't; although you can make it resident, if you try to run a second one
it will be loaded from disk.
John
(are there any guidelines for moving discussions back to comp.sys.amiga if
they become less technical?)