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_FONT_LOW_CONTRAST,HTML_MESSAGE,MAILING_LIST_MULTI, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 27367 invoked from network); 31 Dec 2023 02:27:45 -0000 Received: from minnie.tuhs.org (2600:3c01:e000:146::1) by inbox.vuxu.org with ESMTPUTF8; 31 Dec 2023 02:27:45 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id C9CD943D2C; Sun, 31 Dec 2023 12:27:41 +1000 (AEST) Received: from mail-ua1-x92b.google.com (mail-ua1-x92b.google.com [IPv6:2607:f8b0:4864:20::92b]) by minnie.tuhs.org (Postfix) with ESMTPS id 617EF42441 for ; Sun, 31 Dec 2023 12:27:31 +1000 (AEST) Received: by mail-ua1-x92b.google.com with SMTP id a1e0cc1a2514c-7cc970f8156so655916241.2 for ; Sat, 30 Dec 2023 18:27:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ccc.com; s=google; t=1703989650; x=1704594450; darn=tuhs.org; h=to:subject:message-id:date:from:in-reply-to:references:mime-version :from:to:cc:subject:date:message-id:reply-to; bh=7QwdR4rLXJPmHLYgzbvL4OtrbMeqYl+/TdJKH0g0VPg=; b=ScA76YEXN0hxJppy6NiRIXZRp5G7qIH2ZVeNlt84l7onpOsks1uPcr0sRtTh1qJpw0 3mc5ot786sSJzEZ8MDimIO4tQcNZ33WusBEMJIV6IL0NyQqCbFizXJUKt0GWjjtdmh/X MVJV4npbOBZ9RnR09tIs0jUdXZNXjYxVzqCzA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703989650; x=1704594450; h=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=7QwdR4rLXJPmHLYgzbvL4OtrbMeqYl+/TdJKH0g0VPg=; b=a/R5CaSJEovlcXii96eBJ35ryUZdoxgnHyNTkuOGIOX6R2eRP4C071nVWjS61PHAnk 20c3oFgeFXCdvb6rvd/gS71GkXRRcZEQnmONcDHTfaMFwYqSEE/epvXrfPxvUNfmxKDt F9JIrLO5ALQRv7xCA+gmqCUmctaZyJOjzqpqiijPSFJWtwMCZItVfL+AXsvfUSM/VeAg ux3tGVQXp7t2XtoNd+U0UfNVh0cj0iLgO42CXCzHWNdH72s1I6YW/KcuemwYUCRf9F0Z yxHGA39I9wAoKxs4iRFumTI5V9ebiB3RMGKAdUroZ5cc1zM+UDLPeFWR/MsXR86B1qLv 6uqg== X-Gm-Message-State: AOJu0YwPhg5XwPd2T6O8oNNw60FDP7429bR2QIppXn5wpkRahG+esTAy AcTB0V9quzVKbnGr13shctwwLHcj1efeyvjiNtMeoJnbFITg6mctdW7cEXY= X-Google-Smtp-Source: AGHT+IG2huxlaEVEDFfwBCgceSbkAsiy88QuidHnR7DkdNNNr3ZKK9mRHPId1iYFbBkNz0KX+/PtFaBPStubyKKvzbU= X-Received: by 2002:a05:6102:32d6:b0:467:7583:1046 with SMTP id o22-20020a05610232d600b0046775831046mr150018vss.18.1703989649719; Sat, 30 Dec 2023 18:27:29 -0800 (PST) MIME-Version: 1.0 References: <656c72ae-2b6e-487c-a7bc-6e3a3896b49f@ieee.org> <53587999-897f-4b69-b476-b1c83dfaf816@ieee.org> <2cafc131-3e5d-4bf1-b0ee-537e3ed0f4cd@ieee.org> <75e8f333-98fc-45da-b109-fedaa9d78fdb@ieee.org> In-Reply-To: <75e8f333-98fc-45da-b109-fedaa9d78fdb@ieee.org> From: Clem Cole Date: Sat, 30 Dec 2023 21:27:18 -0500 Message-ID: To: Computer Old Farts Followers , "nw.johnson@ieee.org" , simh@groups.io Content-Type: multipart/alternative; boundary="000000000000c5e0c6060dc50142" Message-ID-Hash: YNF5PRPQ4TMAOVXHXVLEIIX6F4TR623D X-Message-ID-Hash: YNF5PRPQ4TMAOVXHXVLEIIX6F4TR623D X-MailFrom: clemc@ccc.com 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 X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [COFF] Re: [simh] Old VAX/VMS Tapes List-Id: Computer Old Farts Forum Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --000000000000c5e0c6060dc50142 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable We should move to COFF (cc=E2=80=99ed) for any further discussion. This is = way off topic for simh. Below Sent from a handheld expect more typos than usual On Sat, Dec 30, 2023 at 7:59=E2=80=AFPM Nigel Johnson MIEEE via groups.io wrote: > First of all, 7-track vs 9-yrack - when you are streaming in serpentine > mode, it is whatever you can fit into the tape width having regard to the > limitations of the stepper motor accuracy. > Agreed. It=E2=80=99s the physical size of head and encoding magnetics. Pa= rallel you have n heads together all reading or writing together into n analog circuits. A rake across the ground if you will. Serial of course its like a single pencil line with the head on a servo starting in the center of the tape and when you hit the physical eot move it up or down as appropriate. It is nothing to do with the number of bits per data unit. > I did not say that or imply it. But variable vs. fixed blocking has implications on both mechanical requirements and ends up being reflected in how the sw handles it. Traditional 9-track allows you to mix record sizes on each tape. Streamer formats don=E2=80=99t traditionally allow that beca= use they restrict / remove inter record gaps in the same manner 9-track supports. This increases capacity of the tape (less waste). Just for comparison at 6250 BPI a traditional 2400=E2=80=99 =C2=BD=E2=80=9D= tape writing fixed blocks of 10240 8-bit bytes gets about 150Mbytes. A =C2=BC=E2=80=9D DC-615= 0 tape using QIC-150 only one forth the length and half as wide gets the same capacity and they both use the same core scheme to encode the bits. QIC writes smaller bits and wastes less tape with IRCs. That all said, Looking at the TK25 specs besides being 11 tracks it is also supports a small number different block sizes (LRECL) - unlike QIC. Nothing like 9-track which can handle a large range of LRECLs. What I don=E2=80=99t see in the TK25 is if you can mix them on a tape or if that i= s coded once for each tape as opposed in each record. Btw while I don=E2=80=99t think ansi condones it, some 9-track units like t= he Storage Tek ones could not only write different LRECLs but could write using different encoding (densities) on the same medium. This sad trick confused many drives when you moved the tape to a drive that could not. I have some interesting customer stories living those issues. But I digress = =E2=80=A6 FWIW As I said before do have a lot of experience with what it takes to support this stuff and what you have to do decode it, the drivers for same et al. I never considered myself a tape expert- there are many the know way more than I - but I have lived, experienced and had to support a number of these systems and have learned the hard way about how these schemes can go south when trying to recover data. Back in the beginning of my career, we had Uniservo VIC drives which were > actually 7-bit parallel! (256, 556, and 800 bpi! NRZI > Yep same here. =C2=BD=E2=80=9D was 5, 7 and 9 bits in parallel originally. = GE-635 has in the late 1960s then and a IBM shop in the early 70s. And of course saw my favorite tapes of all - original DEC tape. I=E2=80=99ve also watched t= hings change with serial and the use of serpentine encoding. You might find it amusing =E2=80=94 any early 1980s Masscomp machines had a= special =C2=BD=E2=80=9D drive that had a huge number serpentine tracks I=E2=80=99ve= forgotten the exact amount. They used traditional 1/2=E2=80=9D spools from 3M and the like but = r/w was custom to the drive. I=E2=80=99ve forgotten the capacity but at the time= it was huge. What I remember it was much higher capacity and reliability than exabyte which at the time was the capacity leader. The USAF AWACS planes had 2 plus a spare talking to the /700 systems doing the I/O - they were suckling up everything in the air and recording it as digital signals. The tape units were Used to record all that data. An airman spends his/whole time loading and unloading tapes. Very cool system. > Some things about the 92192 drive: it was 8" cabinet format in a 5.25 > inch world so needed an external box. It also had an annoying habit, giv= en > Control Data's proclivity for perfection, that when you put a cartridge i= n, > it ran it back and forth for five minutes before coming ready to ensure > even tension on the tape! > > The formatter-host adapter bus was not QIC36, so Emulex had to make a > special controller, the TC05, to handle the CDC Proprietary format. The > standard was QIC-36, although I think that Tandberg had a standard of the= ir > own. > Very likely. When thoses all came on the scene there were a number of interfaces and encoding schemes. I was not involved in any of the politics but QIC ended up as the encoding standard and SCSI the interface IIRC the first QIC both Masscomp and Apollo used was QIC-36 via a SCSI converter board SCS made for both of us. I don=E2=80=99t think Sun used it= . Later Archive and I think Wangtek made SCSI interface standard on the drives. > I was wrong about the 9-track versus 7, the TC05/sentinel combination > writes 11 tracks! The standard 1/4' cartridge media use QIC24, which > specifies 9 tracks. I just knew it was not 9! > It also means it was not a QIC standard as I don=E2=80=99t believe they had= one between QIC-24-DC and QIC-120-DC. Which I would think means that if this tape came from a TK25 I doubt either Steve or my drives will read it - he=E2=80=99ll need to find someone with a TK25 - which I have never seen personally. > That's all I know! > fair enough Clem_._,_._,_ > --000000000000c5e0c6060dc50142 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
We should move to COFF (cc=E2=80=99ed) for any further di= scussion. This is way off topic for simh.=C2=A0

=
Below

=
Sent from a handheld expect more typos than usual


On Sat, Dec 30, 2023 at 7:59=E2=80=AFPM Nigel Jo= hnson MIEEE via groups.io <nw.johnson= =3Dieee.org@groups.io> wrote:<= br>
=20 =20 =20

First of all, 7-track vs 9-yrack - when you are streaming in serpentine mode, it is whatever you can fit into the tape width having regard to the limitations of the stepper motor accuracy.

Agreed.=C2=A0 It=E2=80=99s the physical size of head= and encoding magnetics.=C2=A0 Parallel you have n heads together all =C2= =A0reading or writing together into n analog circuits. =C2=A0 A rake across= the ground if you will.=C2=A0 Serial of course its like a single pencil li= ne with the head on a servo starting in the center of the tape and when you= hit the physical eot move it up or down as appropriate. =C2=A0


It is n= othing to do with the number of bits per data unit.=C2=A0

I did not say that or imply it. =C2=A0 But variab= le vs. fixed blocking has implications on both mechanical requirements and = ends up being reflected in how the sw handles it.=C2=A0 Traditional 9-track= allows you to mix record sizes on each tape.=C2=A0 Streamer formats don=E2= =80=99t traditionally allow that because they restrict / remove inter recor= d gaps in the same manner 9-track supports.=C2=A0 This increases capacity o= f the tape (less waste). =C2=A0

Just for comparison at 6250 BPI a traditional 2400=E2=80=99 =C2= =BD=E2=80=9D tape writing fixed blocks of 10240 8-bit bytes gets about 150M= bytes.=C2=A0 A =C2=BC=E2=80=9D DC-6150 tape using QIC-150 only one forth th= e length and half as wide gets the same capacity and they both use the same= core scheme to encode the bits.=C2=A0 QIC writes smaller bits and wastes l= ess tape with IRCs. =C2=A0

That all said, Looking at the TK25 specs besides being 11 tracks it is a= lso supports a small number different block sizes (LRECL) - unlike QIC. =C2= =A0 Nothing like 9-track which can handle a large range of LRECLs.=C2=A0 Wh= at I don=E2=80=99t see in the TK25 is if you can mix them on a tape or if t= hat is coded once for each tape as opposed in each record. =C2=A0


Btw w= hile I don=E2=80=99t think ansi condones it, some 9-track units like the St= orage Tek ones could not only write different LRECLs but could write using = different encoding (densities) on the same medium.=C2=A0 This sad trick con= fused many drives when you moved the tape to a drive that could not.=C2=A0 = I have some interesting customer stories living those issues.=C2=A0 But I d= igress =E2=80=A6

FWIW As= I said before do have a lot of experience with what it takes to support th= is stuff and what you have to do decode it, the drivers for same et al. =C2= =A0 I never considered myself a tape expert- there are many the know way mo= re than I - but I have lived, experienced and had to support a number of th= ese systems and have learned the hard way about how these schemes can go so= uth when trying to recover data. =C2=A0

Back in the beginning of my career, we had Uniservo VIC drives which were actually 7-bit parallel! (256, 556, and 800 bpi! NRZI

Yep same here. =C2=BD=E2=80=9D was 5, 7 and 9 bits in pa= rallel originally.=C2=A0 GE-635 has in the late 1960s then and a IBM shop i= n the early 70s.=C2=A0 And of course saw my favorite tapes of all - origina= l DEC tape.=C2=A0 I=E2=80=99ve =C2=A0also watched things change with serial= and the use of serpentine encoding. =C2=A0 =C2=A0
<= br>
You might find it amusing =E2=80=94 any early 19= 80s Masscomp machines had a special =C2=BD=E2=80=9D drive that had a huge n= umber serpentine tracks I=E2=80=99ve forgotten the exact amount. They used = traditional 1/2=E2=80=9D spools from 3M and the like but r/w was custom to = the drive. =C2=A0 =C2=A0I=E2=80=99ve forgotten the capacity but at the time= it was huge. What I remember it was much higher capacity and reliability t= han exabyte which at the time was the capacity leader. The USAF AWACS plane= s had 2 plus a spare talking to the /700 systems doing the I/O - they were = suckling up everything in the air and recording it as digital signals. The = tape units were Used to record all that data.=C2=A0 An airman spends his/wh= ole time loading and unloading tapes. =C2=A0 =C2=A0 Very cool system.


Some things about the 92192 drive:=C2=A0 it was 8" cabinet format in a 5.25 inch world so = needed an external box.=C2=A0 It also had an annoying habit, given Control Data's proclivity for perfection, that when you put a cartridge in, it ran it back and forth for five minutes before coming ready to ensure even tension on the tape!

The formatter-host adapter bus was not QIC36, so Emulex had to make a special controller, the TC05, to handle the CDC Proprietary format. The standard was QIC-36, although I think that Tandberg had a standard of their own.

Very likely.=C2= =A0 When thoses all came on the scene there were a number of interfaces and= encoding schemes. I was not involved in any of the politics but QIC ended = up as the encoding standard and SCSI the interface
<= br>
IIRC the first QIC both Masscomp and Apollo used= was QIC-36 via a SCSI converter board SCS made for both of us.=C2=A0 I don= =E2=80=99t think Sun used it.=C2=A0 Later Archive and I think Wangtek made = SCSI interface standard on the drives.=C2=A0



I was wrong about the 9-track versus 7, the TC05/sentinel combination writes 11 tracks!=C2=A0 The standard 1/4' cartridge media use QIC24, whic= h specifies 9 tracks. I just knew it was not 9!

It also means it was not a QIC standard as I don= =E2=80=99t believe they had one between QIC-24-DC and QIC-120-DC. =C2=A0 Wh= ich I would think means that if this tape came from a TK25 I doubt either S= teve or my drives will read it - he=E2=80=99ll need to find someone with a = TK25 - which I have never seen personally.=C2=A0



That's all = I know!

fair enough

Clem= _._,_._,_

--000000000000c5e0c6060dc50142--