Help to identify this RAMBoard...

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Rodolfo Leal

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Nov 25, 2003, 12:51:04 AM11/25/03
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Hello everybody,
This is a follow-up of my previous posting, regarding my request
for the installation guide of a 1541 RAMBoard.
Forrest has been very helpful, looking at his own board. Mine it's
different. Here's the description:

The board is like 1.5 x 2.5 inches. It has the legend "RAMBoard tm
2/C" in one corner. On the other side it has the legend "(c) 1989
CLD". The board has two chips on it. One of them is a 74139-a
decoder/Multiplexor- and the other is a IMS2630P -a SRAM 8 KB- then it
has a 28 pin socket. It has wires, that are connected to three pads,
that run some lines from the the decoder to the SRAM. It has too what
it seems like a capacitor.

I googled looking for info about this and found that the design is
similar to the one that Michael Klein has in his site:
(http://www.lb.shuttle.de/puffin/8k1541/8k1541.html). My guess is that
it really is a RAM expansion, but without the 40 pin socket, I don't
know how to connect it.
So if anybody has any idea of what kind of RAMBoard is this and how
I might connect it to my drive, I will be very happy. Thanks for your
time.

Regards,
Rodolfo Leal

rebocardo

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Nov 28, 2003, 3:43:48 PM11/28/03
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CLD = Chip Level Designs.

If you had two 1541s with the 8k boards or two MSD drives (either the SD1 or
SD2) , you could load programs into the drives that let them be stand alone
disk copiers. So, if you bought a switch box, like the one I just sold on
E-Bay, you could load and run the program on one set, turn the switch, load
and run on another set of drives, and then be able to fast nibble copy (22
sec.) on two pair of drives entirely separate from a C-64. This way you
could copy about 250 disks per hour with full verify.

As for the actual connection, I can not help you there. I never bought the
1541 boards, just the MSDs. Also, the boards were supported for parameters,
which Maverick will use too.

NiVEK

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Nov 28, 2003, 9:06:56 PM11/28/03
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On 24 Nov 2003 21:51:04 -0800, cpul...@uymail.com (Rodolfo Leal)
wrote:

>The board is like 1.5 x 2.5 inches. It has the legend "RAMBoard tm
>2/C" in one corner. On the other side it has the legend "(c) 1989
>CLD". The board has two chips on it. One of them is a 74139-a
>decoder/Multiplexor- and the other is a IMS2630P -a SRAM 8 KB- then it
>has a 28 pin socket. It has wires, that are connected to three pads,
>that run some lines from the the decoder to the SRAM. It has too what
>it seems like a capacitor.

Your description is different from the Chip Level Designs (CLD) 1541
RAMBOard that I have. I suspect maybe it is a 1571 CLD Ramboard but
I've never seen on of these. If I remember correctly here, the CPU was
soldered in the 1571 (and the memory map is different from the 1541
due to extra ROM) so some other way of adding expansion memory (say,
by interfacing via a ROM socket?) would be necessary. Just my guess,
though.

Kevin.
APPLEuh...@9email.com
Delete the APPLE & 9 for email reply
Spammers, please send spam to m...@privacy.net

Rodolfo Leal

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Nov 30, 2003, 5:43:28 PM11/30/03
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Hi Kevin,
I think you might be on the right track. After I read your post, I
went and opened up my 1571. Inside, the only socketed chip, with a 28
pin layout, it's the ROM chip. I said Forrest that I'll get the
schematics of my RAMBoard. After that, I'll put them on-line so
everybody could have a better idea nad we can figure out how to
connect it.

Regards,
Rodolfo Leal


NiVEK <APPLEuh...@9email.com> wrote in message news:<kavfsvkgru37gi3ea...@4ax.com>...

Rodolfo Leal

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Dec 9, 2003, 2:48:22 PM12/9/03
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Hello everybody,
This is an update of my request. I found out that Kevin is right. I
have a 1571 RAMBoard. Now all I need is information about how to
connect the three wires that come with it.
I'm in the process of cleaning the schematics that I got from my
board. Now I have another problem. The datasheet for the 8 KB SRAM
chip used in the circuit is nowhere to be found. The chip is the
IMS2630P-15.
Because the way it's connected, I believe it could be replaced for
any other 8 KB SRAM with a 28 pin layout. However, the pin number 1 in
this one is used in some way, while most of the replacements like the
6264 have it as not connected.
Anyway, I'll finish the schematics and post them so more people
could help me to find where those wires go.

Regards,
Rodolfo Leal

NiVEK

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Dec 14, 2003, 9:15:43 AM12/14/03
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On 9 Dec 2003 11:48:22 -0800, cpul...@uymail.com (Rodolfo Leal)
wrote:

>Hello everybody,


> This is an update of my request. I found out that Kevin is right. I
>have a 1571 RAMBoard. Now all I need is information about how to
>connect the three wires that come with it.
> I'm in the process of cleaning the schematics that I got from my
>board. Now I have another problem. The datasheet for the 8 KB SRAM
>chip used in the circuit is nowhere to be found. The chip is the
>IMS2630P-15.
> Because the way it's connected, I believe it could be replaced for
>any other 8 KB SRAM with a 28 pin layout. However, the pin number 1 in
>this one is used in some way, while most of the replacements like the
>6264 have it as not connected.

The 8K RAM chip used on my CLD 1541 ramboard is an Intel D2187A-25,
which may be a pin-compatible part. However, this is an old and
obsolete part, and I've been unable to find a datasheet online so far.

On my ramboard, the trace for pin 1 of the 2187 is routed underneath
the board (solder side), so I can't see what it's connected to without
removing the ramboard, which I'm reluctant to do, 'cause the pins are
kinda fragile and I don't want to risk snapping them off. What is pin
1 of the 2650 connected to on your board?

I don't know why something "standard" like a 6264 wasn't used instead
of these weird rams, unless they were cheaper at the time (perhaps
they were already obsolete and thus inexpensive back then).

Rodolfo Leal

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Dec 14, 2003, 6:08:26 PM12/14/03
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NiVEK <APPLEuh...@9email.com> wrote in message news:<rrqotv43h25s50s0c...@4ax.com>...

> The 8K RAM chip used on my CLD 1541 ramboard is an Intel D2187A-25,
> which may be a pin-compatible part. However, this is an old and
> obsolete part, and I've been unable to find a datasheet online so far.
>
> On my ramboard, the trace for pin 1 of the 2187 is routed underneath
> the board (solder side), so I can't see what it's connected to without
> removing the ramboard, which I'm reluctant to do, 'cause the pins are
> kinda fragile and I don't want to risk snapping them off. What is pin
> 1 of the 2650 connected to on your board?
>
> I don't know why something "standard" like a 6264 wasn't used instead
> of these weird rams, unless they were cheaper at the time (perhaps
> they were already obsolete and thus inexpensive back then).
>
> Kevin.
> APPLEuh...@9email.com
> Delete the APPLE & 9 for email reply
> Spammers, please send spam to m...@privacy.net

Hello Kevin,
Well, I made similar discoveries as you do, regarding any datasheet
for the D2187A or the IMS2630P chips. Even I dug out through a
replacement guide that I bought a long time ago, with now luck.
I haven't connected my RAMBoard yet, because the three wires setup.
So, I can tell you that the trace goes from pin 1 of the IMS2360P to
pin 26 of the same chip. The line goes further and uses the pin 13 of
the 74139 and the wire labeled "C".
74139 datasheet's has pin 13 as A1b. A0b (pin 14) gets its feed
from the wire labeled "A". It's connected too at A0a (pin 2). A1a is
connected to ground.
The third wire is connected only to pin 27 of the SRAM chip. So the
wires are used for the bank decoding, but I'm not familiar of which
lines of the 1571 board could map the RAM for the expansion. Any
ideas? :-)

Regards,
Rodolfo Leal

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