>>On Sat, 21 Dec 2013 22:36:42 -0600, you wrote:
>>
>>>The last time I had a chance to tinker with my malfunctioning PDP-8/A
>>>with two RL02's was way back in Feb. 2013... here is the most relevant
>>>tail of the old thread:
>>>
>>>> The connections from the drive select outputs on the RL8A checked
>>>> perfectly to the line receiver inputs on the RL logic board. While I
>>>> appreciate Rick's taking the time to make me a selectable version of
>>>> the RL02 oscillating seek.... he included a bug at no charge too ;)
>>>>
>>>> Specifically, the constant at 0230 (0100) selects the appropriate
>>>> drive and resets it all right (0101 in AC). But - later on down the
>>>> program, the SEEK (03) command is issued with another RLCB... however,
>>>> the AC is forced to 0003 by the microprogrammed 7325.
>>>>
>>>> (As is probably apparent by now, the AC must have 0103 in it to select
>>>> Drive 1).
>>>>
>>>> I edited the program to use a TAD 0231 and put the constant at 0231.
>>>> So instead of the CLA CLL CML IAC RAL (load AC with 03 the hard way,
>>>> an old-time DEC programmer's way to save one word when memory was a
>>>> precious commodity) :) the AC now loads with 0103 and lo and behold,
>>>> Drive 1 seeks merrily away! Restore the two constants to Drive 0 and
>>>> THAT drive seeks. OK.
>>>>
>>>> However, all was not lost... during the couple of hours of chasing my
>>>> tail wondering where the LSB of the drive select was going, I found
>>>> that I had inserted the header into the RL logic board crookedly and
>>>> bent two pins, one in the wrong hole and one shoved aside! :(
>>>>
>>>> Not only that, the line driver chip which provides the drive select
>>>> signals had come from the factory with NO solder at all on its Vcc pin
>>>> 16!
>>>> =:^O
>>>> Fixed that too.
>>>>
>>>> I think the OS/8 packs have been wiped out by now... various FAULT
>>>> lights coming on, especially on the 2nd drive in the chain... going to
>>>> build another system pack with VTserver which takes a good half-hour
>>>> or more at 19200 baud. Hope the servo tracks are ok, otherwise I'll
>>>> need to buy a couple of good packs!
>>>OK. Last week I finally fired up the 8/A again. The problems had
>>>actually gotten worse during the prolonged rest... I couldn't get
>>>either drive to work this time (fault lights on both, as soon as the
>>>Ready lights come on, even before any accesses). After much hair-
>>>pulling and 'scope troubleshooting, I finally found (inside drive 1)
>>>that I had improperly crimped one of the IDC connectors to the ribbon
>>>cable, inside the bottom drive in the rack, where it was making a
>>>variable resistance short between the two sector pulse drive lines!
>>>
>>>So, having fixed that, I verified that Rick's oscillating seek program
>>>works on either drive without faulting. Enter the constants for drive
>>>0, drive 0 seeks no matter whether the first or second drive in the
>>>chain as long as the unit 0 plug is inserted. Same for drive 1. Both
>>>are not being selected simultaneously.
>>>
>>>I also entered a short program to get the two status words, and that
>>>reads the status of either drive correctly (idle, spin up, locked on
>>>track 0, spin down, write protect button pushed).
>>>
>>>Now, the original problem is still there, that OS/8 won't boot and the
>>>RL02 faults (with either the original OS/8 pack that may have been
>>>wiped, AND the remade one). Doesn't matter which drive is used as
>>>Drive 0, or whether the new or the original OS/8 pack... Hit the BOOT
>>>switch and Drive 0 audibly moves its heads, the fault light flashes
>>>briefly, then it goes back to being ready (and of course OS/8 is not
>>>running).
>>>
>>>The interesting part is if both drives are loaded, then the fault
>>>light on *both* drives flashes, then they both go ready again!
>>>I haven't recently tried disconnecting the second drive cable and just
>>>running with one drive, but that wasn't working before, either.
>>>
>>>I am not going to be able to sort this out (unless I use my ancient
>>>Tek 7D01 logic analyzer triggered by the fault signal) without a
>>>diagnostic pack...
>>>
>>>Does anyone have the diagnostic program set for PDP-8 and can put them
>>>on an RL02 disc pack? I could either mail a disc to you, or I could
>>>pay for one if a spare is available.
>>>thanks for any help!
>>>-Charles
>>
>>OK. Got a serial link to my PC going, and successfully downloaded various RL02 diagnostics from the "diagpack2.rk05" image. The seek test works, as does pack verify. However, either drive 0 or 1 flags an error on the read/write test promptly.:
>>
>>WD1 0235
>>WD2 0000 (the two status words from the RL02, and they are normal);
>>ER 2001 (if I'm interpreting this right, this is the Error Register which is showing only an OPI - Operation Incomplete error);
>>CB 0115 (<----------- what is this? ----------)
>>CA 0000 (cylinder address)
>>SA 0100 (sector address)
>>
>>As I posted on another thread, having instructions for these AJxxxx routines would really help, although I can figure much of it out from the RL02 manual, especially if I just use the defaults when prompted.
>>
>>What I think this is telling me is that the problem is somewhere on the controller card, as neither drive will write but both can read without errors.
>>
>>There is a "Diskless RL8A test" (AJRLAC) but I can't figure out how to use it. Anyone got instructions for this one? thanks :)
>
>Read over the RL8A Technical Manual, specifically the write section.
>
>CB = Command Register B, 0115 is Drive 1, memory field 1, Write
>command.
>CA = Command Register A (which also happens in this context to be
>Cylinder Address :) Head 0, Direction Forward, Cylinder 0).
>
>So - the proper write command is being issued on the first
>cylinder/sector address of the platter, but OPI (operation incomplete
>in 200 ms) is the only flag returned. That tells me the fault is
>likely somewhere in the write logic as it appears that nothing is
>being written at all, not just incorrect data or at the wrong time
>which would set other error flags. Will report more when I get another
>chance to work on it!
I think I found the problem (aside from the defective cable previously
described), and "Y'all ain't gonna believe this"...
I toggled in a couple of simple programs to write each register
(Command A, Command B, Word Count, Sector Address) and read them back.
On a few occasions I noticed the SA was not reading the same as
written. And... the returned bit pattern changed when I moved the RL8A
card!
As it turns out, my quad extender card was not lined up perfectly in
the chassis (which is hex-height, and so is the RL8A, but it only uses
four of its six finger sets). I put the RL8A directly in the slot and
re-ran the diskless controller test and it worked flawlessly. Also the
read/write tests now work without all those errors too. I can't
believe I spent hours and hours chasing this :P
However, my OS/8 pack still won't boot. Interestingly, the same boot
behavior is seen with the scratch packs that I used on the read/write
tests (flip the boot switch, the heads move, the fault light flashes,
drive goes back to being ready). So it looks like the OS has been
wiped out and it's time to make another pack on the 11/23+ with
vtserver. We'll see how that goes soon...
Just what a ?carefully researched article? means I?m not sure; an
historian does exactly that or should. But if we historians are not
willing to stand-by our research & printed(electronic, oral &
otherwise) works then why do it in the first place! If I say this is
the evidence I have and did due diligence then I stand by what I have
done. If it is ?corrected? in the future then so be it. But let us not
avoid writing history ?at all costs? just because Will considers them
?the most dangerous words in historic research?. I?d rather have my
opinions out there then not! But so has he. A conundrum indeed.
This applies to the 30th ann. of the MacIntosh. We know its history
but not the underlying reason it was created as S. Jobs is no longer
here. I can surmise what was his intention but that's all. Does this
negate what I do? Hardly!
Murray :-)
BOOT /PT
Rick Bensene
The Old Calculator Museum
http://oldcalculatormuseum.com
-----Original Message-----
From: Marc Howard [cramcram at gmail.com]
Received: Saturday, 25 Jan 2014, 1:49PM
To: General Discussion: On-Topic Posts Only [cctech at classiccmp.org]
Subject: Quick way to load bin loader into memory from OS8
I seem to recall seeing that the BIN (and probably RIM) loaders can be
loaded with a single command from OS8. What's the magic command?
Thanks,
Marc
Picked up this critter yesterday, it's a short (~7") 8-bit ISA card made by
ATD (which the FCC sticker tells me is Advanced Transducer Devices) with a
female DB-25 and female DE9 connector on the rear edge.
There's a 40-pin IC on it labeled 'printer', as well as a 24-pin IC labeled
'mono', and a 6845 CRT controller. Fair enough, and initially I'm thinking
that it's just a reworked clone of an IBM MDA card - but also present on
the board are two 48-pin ICs, which suggests there might be more to it than
that; sure, I remember there being a lot of TTL logic on the IBM MDA board,
but I'm surprised it needs two 48-pin ICs to condense it all.
Unfortunately the pair of 48-pin chips are custom parts (as are the 'mono'
and 'printer' ICs) - one's branded ATD1/BLOWD/802D8643LD and the other
ATD2/WIND/8038637LDC.
Does anyone remember this board and can tell me if it is something more
than just MDA/parallel? There's no separate ROM chip, but I suppose it's
entirely possible that it has some firmware embedded in one of the large ICs.
cheers
Jules
It looks like I might have an extra RK05j available, but first, a question:
Can a reasonable PDP-11/45 system be made using a single RK05? The
system I have has been hacked up and modified so much from its gas
chromatograph days that I feel like I can justify fooling around with
it any way I like. It has no disk, but I am pretty sure I can slide an
RK05 in the rack (it is a two rack system, with the second rack being
a TU10). I do not think a second RK05 will fit, so that one will
likely be available. Please ask off list.
--
Will, 10512. Yes, it is a zip code.
I appreciate all the hearty discussion in response to the article:
http://www.tronola.com/html/who_built_the_first_minicomput.html
There are some points that I would like to respond to:
>It perpetuates the myth that there was such a thing as a "minicomputer" before the late 60's. There have been several threads now on the origin of the term...
--- In no way did I mean to suggest that the TERM minicomputer was used contemporaneously with the machines which I found to be classifiable as minis. Rather, I am trying to clarify what that term has come to mean. From there, I proceeded to look for the first machines that fit that definition. Now, I certainly don't claim that the definition I propose is the very best one and would appreciate helpful comments on improving it.
>There have been numerous attempts to redefine the boundaries based on [various criteria] ALL such redefinitions, that ignore the fundamental nature of being MARKETING terminology...
---Marketing people might have originated the term minicomputer but like all words, it is defined by the people who use it. We do in fact use it and others seem to know what we mean. My task was to clarify what people do mean by it.
>Likewise, the use of the word "first" is fraught with danger without completely ARBITRARY further stipulations...But, the boundaries are undefined, or rather, everybody has a unique definition of the boundaries of their own.
--- I totally agree that "first" would be meaningless without first defining what you are saying is first. Rather than using arbitrary criteria with which to define mini, I tried to find ones which could be justified and that many could agree upon. For each factor, I looked for good common-sense reasons that it needed to be so and stated those. If I am off base on some, I would appreciate feedback on what you think would be better.
>Are we talking about working prototype? announcement? orders taken? first delivery? full retail availability?
--- It was stated that first production ship date would determine priority. Please see the article for the justifications for that. I think you will find that this is what makes sense.
>Should limited production machines be excluded?
--- The requirement was simply that it must have been manufactured in quantity. Fortunately, the exact quantities shipped did not become an issue for minis. The lowest quantity machine was probably the LINC, of which some 50 or so were made.
Thanks,
Steve L.
http://www.tronola.com/
Hi, All,
Much like the famous XX2247 key for DEC gear, apparently the
default key for a number of TI machines, including the TI980B,
is a Chicago Lock cut to code C2132 (the code is typically
stamped on the key). Does anyone have such a thing and
can spare one? I have a TI980B and no key.
Thanks for looking,
-ethan
The Bendix G-15 was conspicuously left out, although I think
it meets all the requirements. it was the size of a
refrigerator,
weighed 800 Lbs, had several K of drum memory (not "RAM")
had an IBM executive typewriter for I/O, and ran a version
of Algol.
Jon
What about the Bendix G15? Introduced in 1953. Definitely fits the criteria outlined in the article.
Not that I agree with the article..like many others here feel, the term `first` in a historical context is too fraught with issues of definition.
Rick Bensene
-----Original Message-----
From: Chuck Guzis [cclist at sydex.com]
Received: Friday, 24 Jan 2014, 9:17AM
To: General at bensene.com [General at bensene.com]; Discussion at bensene.com:On-Topic and Off-Topic Posts [cctalk at classiccmp.org]
Subject: Re: Who built the first minicomputers?
I'm surprised that the Packard-Bell PB250 wasn't considered. It could
run from a standard US lighting circuit. Circa (IIRC) 1959. Not a drum
machine, but used a recirculating magnetostrictive memory.
It also seems that there may have been a few military computers that
would satisfy your criteria.
As Will has stated "first" is a very dangerous word and "minicomputer"
is, in fact, a term of art. Like pornography, it's what it is because
someone says so.
--Chuck
