Looking for Sharp LH2833-15 part and/or data sheet

[drk421]

I'm looking for a Sharp LH2833-15 IC and/or data sheet. I had one of
these go bad, and I need a replacement. I've tried many of the online
"old" IC sellers, but they want a minimum order of $500-$1000.

If anyone has a data sheet or any information on the pinout I could
substitute another IC. I believe its a DRAM as I've found some info
here:

http://nesdev.parodius.com/FDS%20technical%20reference.txt

It shows some of the pinouts, but I don't know any of the address
lines or CAS/RAS.

Thanks!

- drk421@gmail.com

 

[Franc Zabkar]

On 24 Aug 2004 16:47:47 -0700, drk421@gmail.com (drk421) put finger to
keyboard and composed:

I'm looking for a Sharp LH2833-15 IC and/or data sheet. I had one of
these go bad, and I need a replacement. I've tried many of the online
"old" IC sellers, but they want a minimum order of $500-$1000.

If anyone has a data sheet or any information on the pinout I could
substitute another IC. I believe its a DRAM as I've found some info
here:

http://nesdev.parodius.com/FDS%20technical%20reference.txt

It shows some of the pinouts, but I don't know any of the address
lines or CAS/RAS.

The short story: I suspect the LH2833 is an 8Kx8 EEPROM.

Now for the long story.

The above URL has the following pinout diagram. It is the result of
some reverse engineering by the author who is not certain as to what
the part actually is.
___ ___
|* \/ |
PHI2 >01] [28< VCC
(60) [02] [27< A13
(15) [03] [26< A14
(12) [04] [25< /PRG
(13) [05] [24] (11)
(14) [06] [23] (10)
A7 >07] [22] (09)
(58) [08] LH2833 [21< R/W
(59) [09] [20< VEE
-- [10] [19] D4
D5 [11] [18] D3
D6 [12] [17] D2
D7 [13] [16] D1
VEE >14] [15] D0
|________|

The author believes that the LH2833 is a 32Kbit DRAM. However, this
would make it a 4K x 8 part, which means that it would have 12 address
bits, which implies only 6 muxed address lines. AFAICS, this chip has
much too many pins for it to be a DRAM. I doubt that it is an SRAM
either because the LH28 part number prefix is used by Sharp's LH28F
EEPROMs. So maybe it is really an EEPROM, or perhaps a PROM or OTP
EPROM.

During the early '80s, Intel, AMD, Xicor and others produced the 2817A
and 2864B which were 2Kx8 and 8Kx8 EEPROMs, respectively. Intel's
pinouts are slightly different to the LH2833, although both chips come
in 28-pin DIPs.

This is the pinout for the 2864B:
___ ___
|* \/ |
RDY/BUSY* [01] [28] VCC
A12 [02] [27] WE*
A7 [03] [26] NC
A6 [04] [25] A8
A5 [05] [24] A9
A4 [06] [23] A11
A3 [07] [22] OE*
A2 [08] 2864B [21] A10
A1 [09] [20] CE*
A0 [10] [19] I/O7
I/O0 [11] [18] I/O6
I/O1 [12] [17] I/O5
I/O2 [13] [16] I/O4
GND [14] [15] I/O3
|________|

Pin 20 of the LH2833 is possibly an OE* or CE* (output/chip enable).
The data pins (D0-7, I/O0-7) appear to match up with Intel's, although
not necessarily in the same order. Intel's RDY/BUSY* pin goes low to
inform the host CPU when a write operation is in progress, and returns
to the high state when writing is completed. The CPU's RD* and WR*
pins would probably connect to OE* and WE*. The author states that
"the DRAM (sic) is mapped in at $6000..$DFFF". This would suggest that
address bits A14 and A13 would be set to 1, and A15 would be 0. This
appears to be supported by the author's statement that "/PRG is the
NES/FC's A15 line NAND gated with the PHI2 line". This would suggest
that these three pins may be involved in some kind of chip select
function.

The RAM adaptor described in the above URL consists of three main
chips, a 2C33 mask ROMmed (?) uP, an 8Kbit RAM, and the LH2833.
This layout alone suggests to me that the LH2833 is some kind of ROM
device.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[Franc Zabkar]

On Fri, 27 Aug 2004 07:19:21 +1000, Franc Zabkar
<fzabkar@optussnet.com.au> put finger to keyboard and composed:

The short story: I suspect the LH2833 is an 8Kx8 EEPROM.

Sorry, that should be "4Kx8".


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[drk421]

Wouldn't that be 32K Bytes?

If I'm not mistaken $6000..$DFFF is 32K Bytes, not 4Kx8 (32K bits).
I have this same piece of gear (FDS RAM Adapter), and the LH2833-15
chip has given out. I'm certain of this, because borrowed a friends
unit, swapped out just this chip and it worked fine.

My question is, how can I find out enough information about this chip
(LH2833) to replace it with something more common (such as a 28F256).




Franc Zabkar <fzabkar@optussnet.com.au> wrote in message news:<3buti0dq0usltk003va1l3urh96armdfu2@4ax.com>...

On Fri, 27 Aug 2004 07:19:21 +1000, Franc Zabkar
fzabkar@optussnet.com.au> put finger to keyboard and composed:

The short story: I suspect the LH2833 is an 8Kx8 EEPROM.

Sorry, that should be "4Kx8".


- Franc Zabkar

 

[Franc Zabkar]

On 30 Aug 2004 15:30:25 -0700, drk421@gmail.com (drk421) put finger to
keyboard and composed:

Wouldn't that be 32K Bytes?

If I'm not mistaken $6000..$DFFF is 32K Bytes, not 4Kx8 (32K bits).

Yes, you're right. If I've steered you down the wrong path, then I'm
sorry.

After more research it appears that Famicon games are organised as 32K
bytes of "PRG" memory and 8KB of "CHR" memory. So maybe the LH2833 is
a DRAM after all, although it bears no similarity to any memory device
I've ever seen. It appears to have much to many pins for a DRAM, but
not quite enough for a 32KB SRAM or EEPROM. The choice of part number
is very odd, as the "28" is used by EEPROM devices. FWIW, the 2817 and
2864 EEPROMs of the time were accessed in the same way as SRAMs,
without any special programming algorithm. Also the "33" suggests a
capacity of 32K bits, which is how memory devices are generally
identified. All in all, the LH2833 seems to be a very peculiar device.
I doubt that you will find an equivalent part.

I have this same piece of gear (FDS RAM Adapter), and the LH2833-15
chip has given out. I'm certain of this, because borrowed a friends
unit, swapped out just this chip and it worked fine.

My question is, how can I find out enough information about this chip
(LH2833) to replace it with something more common (such as a 28F256).




Franc Zabkar <fzabkar@optussnet.com.au> wrote in message news:<3buti0dq0usltk003va1l3urh96armdfu2@4ax.com>...
On Fri, 27 Aug 2004 07:19:21 +1000, Franc Zabkar
fzabkar@optussnet.com.au> put finger to keyboard and composed:

The short story: I suspect the LH2833 is an 8Kx8 EEPROM.

Sorry, that should be "4Kx8".


- Franc Zabkar

http://www.nesworld.com/famidisk.htm

"As a Famicom disk rom the SMB 2 is 65kb but when it's split up in PRG
and CHR and like a normal Famicom game it's only 40kb (PRG = 32kb and
CHR = 8kb)."

http://www.nesworld.com/acc/diskspec.txt

7. Emulator correspondence method
-Use $6000-$DFFF for RAM



- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[drk421]

Again,
Thanks for all your help!

I found a company in San Jose, CA (Hackett Electronics) that sells
old, obsolete ICs. Once I got the new chip in there, the device worked
fine.

I would still like to find out what the specs are for this chip. I
called up Sharp, and they don't have any information. Maybe they only
have the data sheets on microfiche or their American offices have no
info.


Franc Zabkar <fzabkar@optussnet.com.au> wrote in message news:<srj9j05m93ucs98ft537u25ahhnr6ekims@4ax.com>...

On 30 Aug 2004 15:30:25 -0700, drk421@gmail.com (drk421) put finger to
keyboard and composed:

Wouldn't that be 32K Bytes?

If I'm not mistaken $6000..$DFFF is 32K Bytes, not 4Kx8 (32K bits).

Yes, you're right. If I've steered you down the wrong path, then I'm
sorry.

After more research it appears that Famicon games are organised as 32K
bytes of "PRG" memory and 8KB of "CHR" memory. So maybe the LH2833 is
a DRAM after all, although it bears no similarity to any memory device
I've ever seen. It appears to have much to many pins for a DRAM, but
not quite enough for a 32KB SRAM or EEPROM. The choice of part number
is very odd, as the "28" is used by EEPROM devices. FWIW, the 2817 and
2864 EEPROMs of the time were accessed in the same way as SRAMs,
without any special programming algorithm. Also the "33" suggests a
capacity of 32K bits, which is how memory devices are generally
identified. All in all, the LH2833 seems to be a very peculiar device.
I doubt that you will find an equivalent part.

I have this same piece of gear (FDS RAM Adapter), and the LH2833-15
chip has given out. I'm certain of this, because borrowed a friends
unit, swapped out just this chip and it worked fine.

My question is, how can I find out enough information about this chip
(LH2833) to replace it with something more common (such as a 28F256).




Franc Zabkar <fzabkar@optussnet.com.au> wrote in message news:<3buti0dq0usltk003va1l3urh96armdfu2@4ax.com>...
On Fri, 27 Aug 2004 07:19:21 +1000, Franc Zabkar
fzabkar@optussnet.com.au> put finger to keyboard and composed:

The short story: I suspect the LH2833 is an 8Kx8 EEPROM.

Sorry, that should be "4Kx8".


- Franc Zabkar

http://www.nesworld.com/famidisk.htm

"As a Famicom disk rom the SMB 2 is 65kb but when it's split up in PRG
and CHR and like a normal Famicom game it's only 40kb (PRG = 32kb and
CHR = 8kb)."

http://www.nesworld.com/acc/diskspec.txt

7. Emulator correspondence method
-Use $6000-$DFFF for RAM



- Franc Zabkar