From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, HTML_MESSAGE,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 502 invoked from network); 19 Sep 2023 03:59:06 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 19 Sep 2023 03:59:06 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 23C81402A1; Tue, 19 Sep 2023 13:59:01 +1000 (AEST) Received: from mail-ua1-x930.google.com (mail-ua1-x930.google.com [IPv6:2607:f8b0:4864:20::930]) by minnie.tuhs.org (Postfix) with ESMTPS id BBE04402A0 for ; Tue, 19 Sep 2023 13:58:55 +1000 (AEST) Received: by mail-ua1-x930.google.com with SMTP id a1e0cc1a2514c-7a50bd29064so1611471241.3 for ; Mon, 18 Sep 2023 20:58:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ccil-org.20230601.gappssmtp.com; s=20230601; t=1695095934; x=1695700734; darn=tuhs.org; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=yWwdZPfSj2BpLyEpYkIJxyJ54CLhL763cOn2xCti5dg=; b=WvzlkrrK4kshqXSrhAA3Frq9VxZ+7awLQfO97MiLFEtikxfwDw3HBSeKZ9nRB2/pup 4NedrTJVHxf+1UskuduequOzNoytKRZu4KNill8WZlZhGfE8fXshN8EjVI12mH7OqYlo jM4F1BLDxpOGwRA8jiPTuPBiNuegdFaBw87PMoZ6NQT8wa68NOQl15Pqu0mqXPU2YOyd ZC7Xlipzl6dvxOMXH2iDlfKVQMpEizMU0zSQNSmqIn3IV85JphD+r6c3sUFZNpxDR1x5 zSdBpdWbkoxovCN/HExlSQp/oNw3tpXzyQhfzl6+Cj448zDq2V436fG65qCEb1XtOxgv WGJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695095934; x=1695700734; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=yWwdZPfSj2BpLyEpYkIJxyJ54CLhL763cOn2xCti5dg=; b=dxIaY6jnM9b90TQ9k53TccrN9gFwtJ062xJfCaxobpfqk5P7PG4echfqSEFY3L0OwC bwUxjz5z7ZZ83CEiuejTrBo7lI15G5+mOwvH80tBTFaZy3AqdwZk8MW1kF7YmTvRFRAK sZyOXFINt7V6FmmxF/GgRz7tQ7WUW71QxxWK5GW2nJIuhr0oC4KcZttgaUJh/hfIHxnr 7X7u1maRlJcuwdhT9Z2sGslh9P8Tw7+OMdUJDWZjmcH5jRCtpSRBxHqr/B5leXA73bFW 7X4bYFs5Yi7xGTFaV5YP+Sea4xpjyVd2ATJuX2K0+W0EJXe6oTtrku13cpyY2n2/2vYN gn6g== X-Gm-Message-State: AOJu0YwqN91fh0UnwQtulu9sbcKkFKjVfYgLcB/dsR/Ipu3yJyL4FEgF FxBpa6yZG7pH8tT4DSld8xET5rCtPthbdOOdjrA6pel5OYcs8xf9N3o= X-Google-Smtp-Source: AGHT+IGN1NgIKCJ13o0aVTDcuCX+QKUIz37ZR7GU3SsANEj6Oa4od6xBHTV5kBjT8tzKJSfqSDgkfCLWg0sjR4gCF2Q= X-Received: by 2002:a67:ecce:0:b0:44e:b77e:f976 with SMTP id i14-20020a67ecce000000b0044eb77ef976mr6337582vsp.20.1695095934697; Mon, 18 Sep 2023 20:58:54 -0700 (PDT) MIME-Version: 1.0 References: <81B4F221-C3EF-4543-84CD-78E52ABF0E67@planet.nl> In-Reply-To: From: John Cowan Date: Mon, 18 Sep 2023 23:58:42 -0400 Message-ID: To: Dan Cross Content-Type: multipart/alternative; boundary="0000000000000c57380605ae47e6" Message-ID-Hash: T3XDKZPSYJBUPNK4CYJAB55QYG2Q377W X-Message-ID-Hash: T3XDKZPSYJBUPNK4CYJAB55QYG2Q377W X-MailFrom: cowan@ccil.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Paul Ruizendaal , "tuhs@tuhs.org" X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: x/y/zmodem on Unix List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --0000000000000c57380605ae47e6 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Sep 18, 2023 at 7:08=E2=80=AFPM Dan Cross wrote: but there was no total byte > count, so it was assumed that the final block would be padded with a > throwaway character. > CP/M, like RT-11 and OS/8 before it, did not track the sizes of files in bytes or words, only in blocks. Text files ended in ^Z and were then padded with either NULs or more ^Zs if necessary; binary files were usually padded with NULs. ZMODEM was, as I understood it, designed for transfers across telenet, > which was pretty reliable; instead of the highly synchronous > send/wait-for-ack cycle of xmodem and ymodem, zmodem relies on error > detection and correction and is basically a streaming protocol: a > packet in a sliding window could be NAK'ed, thus rewinding the > transfer, but otherwise it basically just sends data until done. > It's an analogue of TCP/IP, in fact. --0000000000000c57380605ae47e6 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Mo= n, Sep 18, 2023 at 7:08=E2=80=AFPM Dan Cross <crossd@gmail.com> wrote:

but t= here was no total byte
count, so it was assumed that the final block would be padded with a
throwaway character.

CP/M, like RT-11 and OS/8 before it, did not track the sizes of files in= bytes or words, only in blocks.=C2=A0 Text files=C2=A0ended in ^Z and were= then padded with either NULs or more ^Zs if necessary; binary files were u= sually padded with NULs.

ZMODEM was, as I understood it, designed for transfers across telenet,
which was pretty reliable; instead of the highly synchronous
send/wait-for-ack cycle of xmodem and ymodem, zmodem relies on error
detection and correction and is basically a streaming protocol: a
packet in a sliding window could be NAK'ed, thus rewinding the
transfer, but otherwise it basically just sends data until done.

It's an analogue of TCP/= IP, in fact.
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