11 Apr
2007
11 Apr
'07
10:51 a.m.
the IBM AT used two 64K piggybacked chips for a total of 128K. I don't have the chips
is front of me right now, so I can not tell you if they were MOT chips or not.
As for possibilities, all one has to do is approach a chip mfg and ask them to create the
bond out of the chips so they can be piggybacked. Not all that hard when you have money to
throw at a company. I am sure that is what IBM did. All that would need to be done is swap
an unused pin with a chip select pin. One line goes to the top chip and the other goes to
the bottom chip. Power, RAS, CAS, address and data can all be connected together.
best regards, Steve Thatcher
By the way, I did not read any of the other posts on this topic, so please forgive my
intrusion if not helpful.
-----Original Message-----
From: Alexandre Souza <alexandre-listas at
e-secure.com.br>
Sent: Apr 11, 2007 7:19 AM
To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org>
Subject: Re: MCM66128L20
>That's the first thing that puzzles me. It
was my understanding that
>these were 128Kbit chips, so 18 of them would give you 256K bytes (+
>parity) of memory. Can you confirm, please, that 18 of them really are
>512K
>> The top chips are stamped MCM66128L20; the bottom chips have no part
>> number.
Maybe the bottom chips are just EMI filters/pull ups??? :oO
There are NO possibilities that memory can be piggybacked this way. When
you piggyback two memory chips, at least ONE of the pins must be routed
separately. At least this is what logic tells me.
I never seen a 128K *D*ram chip. SRAM exists. This is something that is
driving me crazy here, I cannot find any datasheets/pinouts on this part
number, nor any kind of info. Crazy.
IF the memory was 16-bit-word, maybe you could be using 256K chips
What was the replacement part you got?
Greetings,
Alexandre
11 Apr
11 Apr
12:32 p.m.
On 11 Apr 2007 at 0:00, Steve Thatcher wrote:
the IBM AT used two 64K piggybacked chips for a total
of 128K. I don't
have the chips is front of me right now, so I can not tell you if they
were MOT chips or not.
What I said earlier. The 128K chips in question are probably nothing
more than the old Rev I PC-AT planar chips. AFAIK, it's not possible
to use any conventionally (64K/256K) DRAM in these sockets without
some PCB cuts and jumpers.
The technique is still being used today: google the phrase "stacked
RAM".
A "cheap and dirty" memory epansion for the Atari 540ST was, if I
remember correctly, to piggyback additional DRAM, with the exception
of one select line, which was run via wire to a different point.
The "half good" memory dates back long before 256K chips--it goes all
the way back to 16K ones. I've got a batch of Intel 2109s that
differ from each other by a suffix -1 or -2. The idea is that the
suffix indicates which half is good; otherwise the chips are
electrically the same. I remember when the local Intel sales guy
dropped off a bag of the things on my desk and I sorted through them
and found a batch where all 16K worked in my application.
Cheers,
Chuck
7:19 p.m.
Hi,
A "cheap and dirty" memory epansion for the
Atari 540ST was....
Here in Europe we had the "520" and the "1040" (and later Mega 1 &
Mega 2),
did Atari market them under slightly different names in the US, IE "540ST"?
The "half good" memory dates back long
before 256K chips--it goes
all the way back to 16K ones....
I believe (though have not verified it myself since I utterly despise the
machines) that Sinclair used this technique in the early Spectrums; they,
apparently, simply disabled the faulty half of the DRAMs using jumpers on
the board.
TTFN - Pete.
9:58 p.m.
On 12 Apr 2007 at 0:19, Ensor wrote:
Hi,
Nope, just a picked of bits in the ol' noggin. 520 and 1040. I
should remember that now that tax time approacheth. :-) (The base
Federal income tax form in the USA is known as a "Form 1040" and is
dreaded and despised by all). Let's see, I have seven wives, all
over 65 and blind, that's 21 deductions...
When the 16K DRAMs were first coming out, there was a serious
shortage of them for a time (yields were very low), so the "half
good" parts were better than nothing. The moment the manufacturers
got 16Ks popping out at a reasonable yield rate, the "half goods"
disappeared like a bad dream.
Cheers,
Chuck
A "cheap and dirty" memory epansion for
the Atari 540ST was....
Here in Europe we had the "520" and the "1040" (and later Mega 1
& Mega 2),
did Atari market them under slightly different names in the US, IE "540ST"?
13 Apr
13 Apr
8:21 p.m.
Hi,
The reason I asked is that I dimly recall reading somewhere on the 'net that
there was (or was to be) a 540ST (or was that a 260ST?).
TTFN - Pete.
Here in Europe
we had the "520" and the "1040" (and later Mega
1 & Mega 2), did Atari market them under slightly different names
in the US, IE "540ST"?
Nope, just a picked of bits in the ol' noggin. 520 and 1040.... 
8:36 p.m.
New subject: Atari ST/STacy was Re: MCM66128L20
The reason I asked is that I dimly recall reading
somewhere on the 'net that
there was (or was to be) a 540ST (or was that a 260ST?).
I know of a 260ST, not a 540. There was also talk of a 130ST.
Incidentally, I managed to land a STacy recently. Any suggestions from
other users for upgrades, etc.?
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- You are not ready! ---------------------------------------------------------
10:54 p.m.
New subject: Atari ST/STacy was Re: MCM66128L20
I have the original 130ST shown at the 1985 CES. The 260ST was
shipped to Europe in limited numbers.
The 520ST was shipping to user groups and developers in June of 1985 and
then general retail in September of 1985 - it shipped with its OS -
"TOS" on Disks as the final prom's for the OS weren't ready at that
time, but followed shortly there after.
In 1986 Atari shipped the 1040ST which had a full 1MB of ram and built
in floppy drive.
STacy's are remarkable machines and when you take into account that they
were smaller and lighter then the Mac portable and its honk'n lead acid
battery - the STacy was a truly remarkable machine.
The original codename for the Atari ST was "RBP" which stood for Rock
Bottom Price.
The STacy was codenamed "BlueJay"
Curt
Cameron Kaiser wrote:
The reason I
asked is that I dimly recall reading somewhere on the 'net that
there was (or was to be) a 540ST (or was that a 260ST?).
I know of a 260ST, not a 540. There was also talk of a 130ST.
Incidentally, I managed to land a STacy recently. Any suggestions from
other users for upgrades, etc.?
14 Apr
14 Apr
1:22 a.m.
New subject: Atari ST/STacy was Re: MCM66128L20
I have the original 130ST shown at the 1985 CES.
There was only one?
STacy's are remarkable machines and when you take
into account that they
were smaller and lighter then the Mac portable and its honk'n lead acid
battery - the STacy was a truly remarkable machine.
Any recommendations for "must get" upgrades? Is it worth it putting more
RAM in it? How difficult is it to shoehorn a hard disk inside (I don't have
the unit yet, it's still in a Fedex truck somewhere).
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- Put your Nose to the Grindstone! -- Plastic Surgeons-Toolmakers Union Ltd. -
9:13 a.m.
New subject: Atari ST/STacy was Re: MCM66128L20
You can find several places that make an ST to VGA adapter cable which
is good.
Ram upgrades are all very easy to install and you can find them from B&C
Computervisions - www.myatari.com and from Best Electronics -
www.best-electronics-ca.com
Look at places like atariage.com in its ST section, several very easy
homebrew IDE interfaces are available or you can pick up a MegaFile HD
which plugs into Atari's ACSI interface (a slight variant on SCSI with
its own self assigning drive # system)
It all comes down to what you are planning to use the ST for, also if
you want to Internet enable your ST look into getting an Ethernec card -
its an NE2000 unit that plugs into the cartridge port and uses a
modified version of the STing Ip protocol.
Curt
Cameron Kaiser wrote:
I have the
original 130ST shown at the 1985 CES.
There was only one?
STacy's are remarkable machines and when you
take into account that they
were smaller and lighter then the Mac portable and its honk'n lead acid
battery - the STacy was a truly remarkable machine.
Any recommendations for "must get" upgrades? Is it worth it putting more
RAM in it? How difficult is it to shoehorn a hard disk inside (I don't have
the unit yet, it's still in a Fedex truck somewhere).
10:40 a.m.
New subject: Atari ST/STacy was Re: MCM66128L20
You can find several places that make an ST to VGA
adapter cable which
is good.
Will a CGA monitor be able to handle 320x200 lo-res? I wonder if people
have tried hooking them up to Commodore 1902s or 1084s.
If I use the composite lines from the monitor on a composite display, what
happens to the main display on the STacy? Does it turn off or stay on?
Ram upgrades are all very easy to install and you can
find them from B&C
Computervisions - www.myatari.com and from Best Electronics -
www.best-electronics-ca.com
But, say, to run things like MIDI applications, games, etc., is it necessary
to have more than 1MB RAM?
Look at places like atariage.com in its ST section,
several very easy
homebrew IDE interfaces are available or you can pick up a MegaFile HD
which plugs into Atari's ACSI interface (a slight variant on SCSI with
its own self assigning drive # system)
This implies that the internal interface for the STacy is SCSI. True?
http://www.janthomas.org.uk/stacy.html
The person I got it from was clueless and had no idea if it had an HD
or not, although the screenshot just showed A and B "floppy drives" (but
there was no second bracket), so installing an HD would be very nice if
I can just get a SCSI mini drive from a donor Mac and slap that in.
It all comes down to what you are planning to use the
ST for, also if
you want to Internet enable your ST look into getting an Ethernec card -
its an NE2000 unit that plugs into the cartridge port and uses a
modified version of the STing Ip protocol.
I might look into that although the Commodores are starting to occupy
more and more ports on the hub these days :)
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- Don't treat fictional people as if they're real. It only encourages them. --
12:10 p.m.
New subject: Atari ST/STacy was Re: MCM66128L20
Rumor has it that Cameron Kaiser may have mentioned these words:
This implies that the internal interface for the STacy
is SCSI. True?
http://www.janthomas.org.uk/stacy.html
My STacy has an internal SCSI Drive - I could take pictures if you like;
the machine is not currently assembled. Unfortunately, I can't actually
rectify that situation, the baggie I had with all the screws for the case &
whatnot was discarded by my wife a few years back -- when I received the
machine, it was as a non-working unit and would probably need (at least)
some soldering work - this rascal's been rather dodgily modified, but
worked for quite a while. Lotsa cold solder joints, tho. :-/
If you do take yours apart, could you tell me what size/length/pitch screws
are needed so I can go buy more? I really would like to get the unit
working again.
Thanks,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Profile, don't speculate."
SysAdmin, Iceberg Computers | Daniel J. Bernstein
zmerch at 30below.com |
6:48 p.m.
New subject: Atari ST/STacy was Re: MCM66128L20
This implies
that the internal interface for the STacy is SCSI. True?
http://www.janthomas.org.uk/stacy.html
My STacy has an internal SCSI Drive - I could take pictures if you like; If you do take yours apart, could you tell me what
size/length/pitch screws
are needed so I can go buy more? I really would like to get the unit
working again.
Sure. It'll be a bit of time because it's still in transit, but when I tear
it down I'll try to get a measurement for you.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- Dalai Lama to hotdog vendor: "Make me one with everything." ----------------
9:17 p.m.
New subject: Atari ST/STacy was Re: MCM66128L20
Rumor has it that Cameron Kaiser may have mentioned these words:
Nah, I'll rip mine open and look. I just need to know if it's a regular
laptop sized drive.
I'd have to look again - I'm not sure if it's a 3.5" wide drive, or
2.5"
wide drive - but IIRC, it's a 3.5" drive.
Thanks! I would certainly appreciate it!
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Profile, don't speculate."
SysAdmin, Iceberg Computers | Daniel J. Bernstein
zmerch at 30below.com |
This implies that the internal interface for the STacy
is SCSI. True?
http://www.janthomas.org.uk/stacy.html
My STacy has an internal SCSI Drive - I could take pictures if you like; If you do take
yours apart, could you tell me what size/length/pitch
screws
are needed so I can go buy more? I really would
like to get the unit
working again.
Sure. It'll be a bit of time because it's still in transit, but when I tear
it down I'll try to get a measurement for you. 
15 Apr
15 Apr
2:11 a.m.
New subject: Atari ST/STacy was Re: MCM66128L20
Cameron Kaiser wrote:
Yup. I have a couple of Ataris - a 520ST and a Mega STe - and no
color Atari display. My Commodore 1084 fronts just about all my 8-bit
and 16-bit boxes.
Doc
You can find
several places that make an ST to VGA adapter cable which
is good.
Will a CGA monitor be able to handle 320x200 lo-res? I wonder if people
have tried hooking them up to Commodore 1902s or 1084s. 
14 Apr
14 Apr
10:12 a.m.
New subject: Atari ST/STacy was Re: MCM66128L20
On 4/14/07 4:54 AM, Curt @ Atari Museum wrote:
I have the original 130ST shown at the 1985 CES.
The 260ST was
shipped to Europe in limited numbers.
The 520ST was shipping to user groups and developers in June of 1985 and
then general retail in September of 1985 - it shipped with its OS -
"TOS" on Disks as the final prom's for the OS weren't ready at that
time, but followed shortly there after.
In 1986 Atari shipped the 1040ST which had a full 1MB of ram and built
in floppy drive.
1040ST lacked a floppy drive. 520STF and 1040STF had floppy drives (hence
the 'F').
,xtG
.tsooJ
--
You know the world is going crazy when the best rapper is a white guy, the
best golfer is a black guy, The Swiss hold the America's Cup, France is
accusing the US of arrogance, and Germany doesn't want to go to war.
--
Joost van de Griek
<http://www.jvdg.net/>
11:10 a.m.
New subject: Atari ST/STacy was Re: MCM66128L20
On 4/14/07 4:54 AM, Curt @ Atari Museum wrote:
I have the original 130ST shown at the 1985 CES.
The 260ST was
shipped to Europe in limited numbers.
The 520ST was shipping to user groups and developers in June of 1985 and
then general retail in September of 1985 - it shipped with its OS -
"TOS" on Disks as the final prom's for the OS weren't ready at that
time, but followed shortly there after.
In 1986 Atari shipped the 1040ST which had a full 1MB of ram and built
in floppy drive.
1040ST lacked a floppy drive. 520STF and 1040STF had floppy drives (hence
the 'F').
,xtG
.tsooJ
--
You know the world is going crazy when the best rapper is a white guy, the
best golfer is a black guy, The Swiss hold the America's Cup, France is
accusing the US of arrogance, and Germany doesn't want to go to war.
--
Joost van de Griek
<http://www.jvdg.net/>
15 Apr
15 Apr
7:13 p.m.
New subject: Atari ST/STacy was Re: MCM66128L20
Hi,
1040ST lacked a floppy drive. 520STF and 1040STF had
floppy drives
(hence the 'F').
Here in the UK we got the "520STM" (no floppy, internal RF modulator) and
"1040STF" initially, and later the "520STFM"; I don't recall if
there was a
"1040STFM".
TTFN - Pete.
12 Apr
12 Apr
2:09 a.m.
You know, IBM's still "stacking" chips:
http://news.yahoo.com/s/nm/20070412/tc_nm/ibm_chip_dc_1
:-)
3 p.m.
I believe (though have not verified it myself since I utterly despise the
machines) that Sinclair used this technique in the early Spectrums; they,
apparently, simply disabled the faulty half of the DRAMs using jumpers on
the board.
I beleive (although, like you I've not checked because, also like you, I
have as little to do with Sinclair machines as possible) that early 48K
SPectrums had 8 16K chips and 8 32K chips. The latter were half-good 64K
chips, there was a link (or maybe a resistor) on the PCB to select which
half would be used. Needless to say all 8 chips had to ahve the same half
good.
-tony
13 Apr
13 Apr
5:30 a.m.
On Thursday 12 April 2007 20:00:08 Tony Duell wrote:
That's right, they did. I have the workshop manual somewhere that details the
jumper settings for all the variants.
IIRC surplus 4164s worked in any machine...
Gordon
I believe
(though have not verified it myself since I utterly despise the
machines) that Sinclair used this technique in the early Spectrums; they,
apparently, simply disabled the faulty half of the DRAMs using jumpers on
the board.
I beleive (although, like you I've not checked because, also like you, I
have as little to do with Sinclair machines as possible) that early 48K
SPectrums had 8 16K chips and 8 32K chips. The latter were half-good 64K
chips, there was a link (or maybe a resistor) on the PCB to select which
half would be used. Needless to say all 8 chips had to ahve the same half
good.
6290
days inactive
6294
days old
19 comments
11 participants
participants (11)
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ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
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curt＠atarimuseum.com -
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gordon＠gjcp.net -
jvdg＠jvdg.net -
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