[Coladam] eBay auction

Geoff Oltmans oltmansg at bellsouth.net
Sun Jun 14 04:55:38 CEST 2009


I think that's a reasonable guess. I was thinking along the same  
lines. Maybe some fancy interface between the ADAM (target) and a host  
programmer system.

On Jun 13, 2009, at 8:12 PM, Daniel Bienvenu wrote:

>
> So, it can be reasonable to think that this thing is to test the  
> super games before making them into tape format? If so, my wild  
> guess in a previous message was partially right!
>
> Daniel
>
> --- En date de : Sam 13.6.09, Geoff Oltmans <oltmansg at bellsouth.net>  
> a écrit :
>
>> De: Geoff Oltmans <oltmansg at bellsouth.net>
>> Objet: Re: [Coladam] eBay auction
>> À: drushel at apk.net
>> Cc: coladam at adamcon.org
>> Date: Samedi 13 Juin 2009, 20h43
>> I agree with your assessment. It is
>> clearly as you say though, a
>> 68701, 1k sram, and an address latch and inverter. This
>> appears
>> numerous times in the ADAM design for ADAM Net. I agree,
>> didn't see
>> any evidence of the LM339 and associated circuitry (which
>> would
>> definitely involve some inductors as well).
>>
>> I wonder if there's any of this circuitry underneath the
>> ribbon cable.
>> It is rather large.
>>
>> The puzzling thing to me is that some of the chips appear
>> to be some
>> interface chips to/from the Z80 bus/expansion connector,
>> which of
>> course you wouldn't/couldn't need for a simple ADAM Net
>> device. Near
>> the expansion connector, I make out two 74LS138s (3-to-8
>> decoders), a
>> 74LS125 quad tri-state buffer, and a 74LS175 quad D flip
>> flop.
>>
>> I believe the small 8 pin chip is an LM347[?]N. Most likely
>> an op-amp.
>>
>> There's an RCA CD4057BN(?) which is described as a 4
>> channel analog
>> mux/demux with logic level conversion. I can't make out the
>> chip above
>> that.
>>
>> I'm tempted to ask the seller to identify each chip.
>>
>> eBay is not difficult to use. You can set up an account
>> easily and
>> you're good to go. As Joe mentioned, the best strategy for
>> winning an
>> eBay auction is to wait 'til the last possible second and
>> place the
>> max bid you're willing to accept. There are a variety of
>> reasons for
>> this:
>>
>> 1. eBay uses a proxy bidding scheme. What this means is
>> that if I want
>> something, I can place a maximum bid and eBay's system will
>> bid up to
>> that amount on my behalf. So, for example if the current
>> bid stands at
>> $10, and the current high bidder enters a max bid of $15,
>> you come in
>> and say bid $14 max, the original high bidder will still be
>> the high
>> bidder at $15. I would have to bid up one step above the
>> original high
>> bidder's bid in order to have the high bid. Another
>> example, if the
>> current bid was $10 (with a max of $15) and I bid a max of
>> $30, the
>> high bid would go to me at $16.
>>
>> 2. Knowing 1, we can see that anybody can simply "bid up"
>> an item by
>> whittling away at your max bid by placing incremental
>> smaller bids up
>> to (and possibly) beyond your max. I bid $11, the original
>> bidder goes
>> up to $12. Then I bid $13, the original bidder bids $14,
>> and so on.
>> This can include sellers who either have a second account
>> set up (or a
>> buddy) to bid up items they feel aren't selling for what
>> they should.
>>
>> 3. Knowing 2, there are "sniper" bidders and/or special
>> software that
>> will wait til the last 30 seconds or so of the auction to
>> place either
>> a max bid, or whittle away at your max until they just
>> surpass it.
>> This gives you little opportunity to counter bid and they
>> win the
>> auction.
>>
>> Clearly the best bidding strategy for eBay is to wait til
>> the last few
>> seconds of the auction, and place the biggest bid you're
>> willing to
>> pay. This gives you the best chance of paying the lowest
>> price and
>> winning an item.
>>
>> I would like to see the guts in person (or higher res
>> pics), beyond
>> that though I'm unwilling to pay what this would ultimately
>> go for I'm
>> sure. It would be a nice piece to have for a collection,
>> but I'm
>> unsure what additional information can be gleaned about the
>> ADAM
>> architecture by having it.
>>
>>
>> On Jun 13, 2009, at 3:34 PM, Rich Drushel wrote:
>>
>>>
>>> On Fri, June 12, 2009 8:26 pm, Frances and/or Richard
>> Clee wrote:
>>>
>>>> Meanwhile, the series of disassembled, closeup
>> pictures is posted so
>>>> perhaps Rich or geoff or Dale or someone can
>> figure out what the damn
>>>> things are, and if the better interests of the
>> Adam community
>>>> suggest we
>>>> pursue them.
>>>>
>>>> So will those who know please speak up?
>>>
>>>      Okay, now that my brain is
>> clear (turns out I was in the onset
>>> stages of a migraine when I was writing last time,
>> eventually my
>>> vision
>>> almost went out and my head was exploding for a few
>> hours, ask Rin how
>>> much sense I was making at the time), and I have had a
>> chance to
>>> examine
>>> the disassembly photos, here is what I think:
>>>
>>> (1)  The most informative photo is the one with
>> the diagonal color
>>> ribbon
>>> cable, since that exposes much more of the underlying
>> circuit
>>> board.  I
>>> will refer to this photo in subsequent points.
>>>
>>> (2)  The large 40-pin ceramic DIP marked "TAPE
>> SIM", with its
>>> associated
>>> chips (TTL logic 74LS273 and 74LS00, 2 static RAMs
>> 2114) and metal
>>> oscillator
>>> crystal, is clearly is 60701 microcontroller (EEPROM
>> version of the
>>> 6801),
>>> suggesting that the board is an ADAMnet device.
>> Somewhere around
>>> should also
>>> be an LM339 quad comparator, a 14-pin DIP, which was
>> always part of
>>> the ADAMnet
>>> interface.  Possibly it is under the multicolor
>> ribbon cables.  If
>>> it is absent,
>>> then whatever the board originally did, it cannot in
>> its present
>>> state be a
>>> functional ADAMnet device, because the LM339 sits
>> between the
>>> ADAMnet bus and
>>> the 68701 -- it would never get any ADAMnet inputs.
>>>
>>> (3)  The circuitry in the vicinity of the added
>> DB-37 connector,
>>> especially
>>> the blue rectangular trimpot (i.e., high-precision
>> variable resistor
>>> with
>>> a tiny adjustment screw sticking out horizontally),
>> suggests to me
>>> that
>>> maybe the original board was a prototype for a disk or
>> tape drive.
>>> I have
>>> looked at the extant schematics
>>>
>>>      http://drushel.cwru.edu/schematics/
>>>
>>> but don't see any immediate matches to the chips whose
>> names I can
>>> read in the disassembly photos.
>>>
>>> (4)  I count 19 wires in the top ribbon cable and
>> 15 in the bottom
>>> cable
>>> (composite of both disassembly photos).  That
>> would leave 3 unused
>>> pins
>>> on the DB-37 connector.  Very likely the signals
>> are 16 address lines,
>>> 8 data lines, 2 ADAMnet lines (data and reset), and
>> presumably other
>>> Z80
>>> control signals of interest that get run out the
>> sideport connector.
>>>
>>> (5)  The circuit board appears to have been
>> designed to fit into the
>>> Expansion Module #1 case, even though the board is
>> clearly *NOT* a
>>> reworked Expansion Module #1 board.
>>>
>>> **** WILD GUESS ****
>>>
>>>      The circuit board was
>> originally for prototype tape drives,
>>> either as a prototype of the (apparently planned,
>> since there are
>>> ADAMnet device numbers reserved for them) tape 3/4
>> expansion unit,
>>> or else for original development of tape drives in
>> general.  Given
>>> how fragile the existing connectors are for the tape
>> drives (plus
>>> the pain of installing them in the first place), I can
>> imagine a
>>> sideport-based unit being easier to plug/unplug during
>> development
>>> cycles.  The "TAPE SIM" 68701 just runs a dummy
>> tape drive device
>>> (or devices).  At the ADAMnet level, all the user
>> cares about is
>>> reading and writing data, and if the 68701 does what
>> is expected,
>>> then it doesn't matter that there is no real tape
>> drive attached.
>>>
>>> ***** END WILD GUESS *****
>>>
>>>      I personally would like to
>> have one of these devices.  But
>>> as stated before, I have never used eBay, so I am the
>> wrong person
>>> to ask about bidding.  But I am willing to
>> contribute $$$ to someone
>>> who knows how to win eBay auctions :-S
>>>
>>>      *Rich*
>>>
>>> -- 
>>> Richard F. Drushel, Ph.D.
>>     | "They fell:  for Heaven to
>>> them no hope
>>> Department of Biology
>>         |  imparts / Who hear not
>> for
>>> the beating
>>> Case Western Reserve University
>> |  of their hearts."
>>> Cleveland, Ohio  44106-7080  U.S.A.
>> |         -- Edgar Allan
>> Poe,
>>> "Al-Aaraaf"
>>>
>>>
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>>
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>
>
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