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Re: microcontroller ROM copy trouble ?



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**new**
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i think i may not be clear  ?
i am saying pin 1 and pin 27 of the memory chip are connected on
the controller board so that would cause special consideration if
one wanted to use a 27c512 ?

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ROM
the
as

close , it is a series of  sections of 64 duplicate bytes
followed by another section of 64 duplicate bytes..... all the
waty to the end

each section of byte values  is different and i get the exact
same series for each successive chip reading attempts.

unless i choose a different chip size like 27c128 then the series
of byte duplicates changes. where the first set maybe 7A in place
of the 02

here is a clip from begining of my read

:020000040000FA
:1000000002020202020202020202020202020202D0
:1000100002020202020202020202020202020202C0
:1000200002020202020202020202020202020202B0
:1000300002020202020202020202020202020202A0
:100040000202020202020202020202020202020290
:100050000202020202020202020202020202020280
:100060000202020202020202020202020202020270
:100070000202020202020202020202020202020260
:10008000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9E0
:10009000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D0
:1000A000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9C0
:1000B000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9B0
:1000C000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9A0
:1000D000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D990
:1000E000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D980
:1000F000D9D9D9D9D9D9D9D9D9D9D9D9D9D9D9D970
:10010000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E68F
:10011000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E67F
:10012000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E66F
:10013000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E65F
:10014000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E64F
:10015000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E63F
:10016000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E62F
:10017000E6E6E6E6E6E6E6E6E6E6E6E6E6E6E6E61F
:1001800039393939393939393939393939393939DF
:1001900039393939393939393939393939393939CF
:1001A00039393939393939393939393939393939BF
:1001B00039393939393939393939393939393939AF
:1001C000393939393939393939393939393939399F
:1001D000393939393939393939393939393939398F
:1001E000393939393939393939393939393939397F
:1001F000393939393939393939393939393939396F
:1002000013131313131313131313131313131313BE
:1002100013131313131313131313131313131313AE
:10022000131313131313131313131313131313139E
:10023000131313131313131313131313131313138E
:10024000131313131313131313131313131313137E
:10025000131313131313131313131313131313136E
:10026000131313131313131313131313131313135E
:10027000131313131313131313131313131313134E
:100280001E1E1E1E1E1E1E1E1E1E1E1E1E1E1E1E8E
.... till the end


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I mapped the pins on the board so as to be reasonably certain
that the ROM chip was compatible with the 27cXXX series of chips

all the pin/address/data lines seem to be consistent with the
27cXXX series pin out. the data and address lines match to the
MCU adressing pins according to 27cXXX datasheet even the funny 8
through 11 pin jumble.

(pin 22) ROM goes to (pin 29) 8051 (PSEN- prog store enable)
(pin 20) ROM  goes to (pin 30)8051 (ALE-Addr Latch Enable)

on the PCB the 8 data lines are all connected with the first 8
Address lines
so D0 is connected to A0 and (D1 to A1) and these shared
connection s all go back to MCU


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thanks for the help,
 robb



Re: microcontroller ROM copy trouble ?



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It would seem your original rom has an internal address latch.
There is *some* evidence that 23256 roms with this feature may have been
used by HP, but I have had no success finding a NEC data sheet for your
rom.  This would explain why the eprom reader reads the same value 64
times and also why there is no 8 bit latch chip between the multiplexed
d0-7/A0-7 MCU bus and the rom's A0-7 address inputs.  Try a different
algorithm for reading the rom on the programmer.  When you've go the
correct contents that dissasemble to something reasonable, you'll need
to put a little board together to insert a latch between the combined
bus and the adddress pins, then program a 27c256 and try it.

HTH

--
Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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Re: microcontroller ROM copy trouble ?




robb wrote:

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Looks like gibberish to me.

What happens if you try reading it as a 27C512 ? Just an idea.

Graham


Re: microcontroller ROM copy trouble ?



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Vpp needs to be held at Vcc for reading.  If it floats you will get garbage
results.

Re: microcontroller ROM copy trouble ?



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The above seems to be the problem.
Your programmer is not reading the original ROM (23xxx) chip
correctly.
However, it "is" reading something.
Later you burn another chip, and this chip correctly burns what was
read previously.
The only problem is, the original read was not right, so it matters
not if the two compare!!

I still contend this is a read problem on the original ROM, likely
related to the signature byte.
To my knowledge, you are unlikely to blow up the original ROM using
read voltages.
As long as you don't try to program it.
So, if you feel its worth the attempt, you could try other 27256
settings and see if you can get something that looks reasonably close
to 8031 opcodes.  (?)

Another posted commented that your 23xxx might have internal address
latches.
Honestly, I've never heard of that.    I doubt they exist, but I could
be wrong.
I am assuming the 23xxx is a factory-masked ROM (i.e., no eprom quartz
window).
If that's the case, very often the 23xxx programming info is on the
same datasheet as the 27xxx of the same manufacturer and model
series.    It might be worth googeling...

And of course, if there are pinout differences between the masked-rom
and eprom versions, your programmer would need to know about these...
and hence we're back to the signature bytes.   Good luck.

-mpm

Re: microcontroller ROM copy trouble ?



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ROM
the
as
was
matters
likely
using
27256
close
Thanks for all the help and info mpm,

i am really stuck and appreciate your's and everyones efforts to
get me going.

that is exactly what i have been trying since the latest round of
**bad ROM read** diagnosis.

I have been selecting a variety of different chip makers versions
of 27cXXX where XXX is ... additionally i have
been choosing different sizes of reads to see if i get anything
that looks like some 8051/8031 op codes. so 0xf  to 0x7fff bytes
and in between


the only difference is that sometimes the sequence of bytes i get
have a different values for the different sized chips

so.... that means a (27c128) read  will get me a different
sequence of repeated chars than say a (27c256) read


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address

well that advice was based on the fact that i traced the pins
connection on the controller circuit board  to try and decipher
what this chip might actaulally be and i found that the

Address lines 0-7 were tied to the Data lines 0-7 and then they
made ther way to the appropriate 8051 lines so being multiplexed
someone though there must be latching operation...

the only 23xxx datasheet i found (toshiba TMM23256P)  says ...
that it uses a Address Latch on the falling edge of (CE) and
latches all inputs except for (OE) to provide data bus
compatibility   and has a reference to 3-State outputs or Wired
OR capability ????? what that means ????

My pin trace  is.....
Where Rom is the same ROM there is only 1 ROM
this views best in fixed width eg. courier

Rom(pin)     Rom(pin)      8051 (pin)
------------------------------------------
A0 (p10)     D0 (p11)      P0.0 (p39)
A1 (p9)      D1 (p12)      P0.1 (p38)
A2 (p8)      D2 (p13)      P0.2 (p37)
......
A8 (p25)     ---           P2.0 (p21)
A9 (p24)     ---           P2.1 (p22)
.....
A14 (p27)    A15 (p1)      P2.6 (p27)
.....
OE (p22)     ---           PSEN (p29)
CE (p20)     ---           ALE  (p30)


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I could
quartz
the
masked-rom
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these...

thanks again MPM,

i really do appreciate the help. hopefully i will solve or find
more useful info that someone can give me an indication of what i
need to do to solve this problem

i am thinikng i will need to use some 8051 development board and
write my own application to grab data and put somewhere to upload
or print on serial port or something

sound feasible,...

Thanks again for help,
robb


Re: microcontroller ROM copy trouble ?


Lets start with a few basics.

Plesae post from your reader the first 16 bytes of the ROM file.

If this does not look right, then everything else will be off.

If the reader can not read it, it won't be able to write anything that
makes sense.

You could always run the exorcised binary file thru a dis-assembler,
re-assemble it, program your EEPROM and see if that runs.

donald

Re: microcontroller ROM copy trouble ?



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file.
anything that
dis-assembler,
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Hello donald thanks for the help,

i agree if you getting crap you write crap,

i though i had allready tested the ROM reads previously and had
success but when i went to recheck i found that the other
microcontroller board was using a 8051 with internal programand
not even uing the ROM

so now i realise that it is reading the ROM that is my problem.

so now how to get programmer to read these ROMS ??

here are first lines from "Easypro90B" programmer read

:020000040000FA
:1000000002020202020202020202020202020202D0
:1000100002020202020202020202020202020202C0

any experience dumping memorywith a 8051 development board ?
i have PJRC Rev 4 board  http://www.pjrc.com /

easier than getting the EasyPRO90B to do it ???

thanks again for the help,
robb



Re: microcontroller ROM copy trouble ?


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Ok, here is your first problem.

At address 0x000 should be a jump to a start address.

02 is a long jmp op-code a nd the target address looks like 0x0202.

http://www.win.tue.nl/~aeb/comp/8051/set8051.html

But then all the interrupt vectors are long jumping to the same address.

This is a problem.

If you can share the entire hex file, maybe someone here be able to help
you read it.

Another idea.

Maybe the address lines are mixed up, so a strait copy would be worng.

good luck.

donald

Re: microcontroller ROM copy trouble ?




robb wrote:

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Judging by the age of this system that may typically be an 8751.

Can you provide the exact part number of the 8051 with suspected
internal program please ?

You can tell if it's using the internal ROM because pin 31 (/EA/Vpp)
will be tied high. It's still possible to read an external ROM in this
mode but it will appear as an 'extension' to the interal ROM with a
start address offset by the size of the internal ROM.

I'm beginning to think you might benefit from a cheap and cheerful
Chinese Eprom/uC reader writer btw. Especially if you need to read the
contents of an 8751 type device.

http://cgi.ebay.co.uk/ADVANCED-EPROM-FLASH-MPU-PIC-USB-Universal-Programmer_W0QQitemZ200186692732QQihZ010QQcategoryZ40004QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.co.uk/USB-TOP2005-Universal-Programmer-TOP2007-2048-2049_W0QQitemZ230207231213QQihZ013QQcategoryZ4663QQrdZ1QQssPageNameZWD2VQQcmdZViewItem?_trksid=p1638.m122



Graham


Re: microcontroller ROM copy trouble ?


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http://cgi.ebay.co.uk/ADVANCED-EPROM-FLASH-MPU-PIC-USB-Universal-Programmer_W0QQitemZ200186692732QQihZ010QQcategoryZ40004QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
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http://cgi.ebay.co.uk/USB-TOP2005-Universal-Programmer-TOP2007-2048-2049_W0QQitemZ230207231213QQihZ013QQcategoryZ4663QQrdZ1QQssPageNameZWD2VQQcmdZViewItem?_trksid=p1638.m122
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Unfortunately he *has* a chinese multi-device programmer
<http://www.programtec.com/english/products/EasyPRO90B.asp

It appears likely that it is the source of his problems, and getting
another similar one *UNLESS* it has *FULL* instructions on implementing
  one's own programming and reading algorithms

It is *supposed* to have lifetime support so it might be worth it for
the OP to contact them with his part number ;-)

The available evidence suggests that the EasyPRO90 he has reads 27xnn
EPROMS using a 'fast' algorithm that reads 64 bytes at a time,
activating /CE continuously and strobing /OE for each byte.
Unfortunately he needs a 'slow' algorithm that strobes *both* signals,
with adequate setup and hold time :-(


A bit of research leads me to the 87C256 Latched EPROM which is intended
for use in applications with /ALE on pin 20.  If his programmer supports
this device or equivalent he should be golden.

If so, and he could source one, or someone can suggest a device with the
same functionality,  it would be a drop in replacement, otherwise, well
I've built all sorts of ROM adaptors 'dead bug' fashion using two
stacked turned pin sockets with the top soldered into the bottom one
with various pins I needed to intercept cut away in between them, kynar
wire, some cotton thread to lace the kynar in place, some SMD TTL and a
few drops of superglue to hold everything together.  Keeps the pins
clean & fit to insert in the programmer and also avoids needing to mod
the equipment PCB (assuming there is ~1cm vertical clearance). :-)



--
Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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Re: microcontroller ROM copy trouble ?



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programand
8751.
suspected
getting
implementing
it for
27xnn
signals,
intended
supports

Thanks for the help Ian,

And the EasyPRO90B  does happen to support a couple of different
varieties of that chip well its cale a (D87c257  Intel ,  M87c257
ST) and when i read selecting these devices i get a more
promising read that i will need to test burn or verify in 8051
disasembler.

i show the output at the end of the reply below...

interestingly a different (NEC D23128AC) gives similar trouble

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with the
otherwise, well
two
bottom one
them, kynar
TTL and a
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pins
to mod
:-)
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by ROM adaptor ? you mean to make the D23256AC look or behave
like some other chip that is supported ??? eg 27C256 etc...

the only difference these amateur eyes could see with the 87c257
was the addition of a latch strobe on the pin 1  ??? and it
coincided almost nearly with the CE . that seems easy enough to
fabricate ?

any ways below is a dump using the 87c257 device

thank you, i appreciate all the effort and help,
robb


D87c257 read....
----------------------
:020000040000FA
:1000000002096FC0D0C0E0020173FFC0D0C0E0029F
:1000100001BEFF30B202D22A32FFFFC0D0C0E0C022
:1000200082C083C000904058E531540F204C073007
:1000300045036001040423F893F58DE80493F58BE0
:10004000E542540790405093F8E541540793C44863
:10005000758360F0206F26D294E530758350F0E50B
:100060002D543F7041C245C28E206F19205D1E1273
:100070000F39D000D083D082D0E0D0D032204DD9FB
:100080007530FF80D4205C4C12154A80E5E5422093
:10009000E002C294E530758350F080D6E54120E05F
:1000A000F353307780EE14601314147002D24CE5D1
:1000B0003130450C540F600215313164316480B227
:1000C000C4B53109C24C1046F1D24580ED104CEA5E
:1000D000053180E6104DC5E520440F20E701C4F549
:1000E00030758DFBD28ED24D53200F80854320F08A
:1000F000E52D543F603AFDF5317842306F0118E646
:1001000030E0021531E531C313B4020575310A80C0
:100110000DC394035001E4C3139246C4F531E6D2F3
:100120004C20E009C24CED1460031201641201641A
:10013000208E20306F06E530C4B53009758DFF750F
...........
skip
...........
:10096000D23D22D23C22E0540F24F650F3808D7504
:1009700090CC797E7802760008D9FB75B8E175894C
:1009800011758CFE75880575A8867583607444F0B2
:1009900075835074FFF530F0758D88D28ED2137543
:1009A000530AD28C120D60308FFA7583507477F52C
:1009B00030F07455758360F0C28F758D88120D60AC
:1009C000308FFA906007E030E002D20A756DE0D215
:1009D00014D2131230A8754400C22C121808C28E0B
:1009E000C28FD2AB1229FCD2192019F82018F5A217
:1009F000B492E0A2B592E1F45403F52B3014102028
:100A0000200D204A472010031218EAC214C2131204
:100A100029FC304A082011E4200DE1800DE5445402
:100A2000F0B4F006202FD52010D220182AD293D26D
:100A300092C295C2D3C2D4A2B492E0A2B592E1F41C
:100A40005403FAE52B5403B5023980B02011BC20C1
:100A50000DB91231A780B4D2193014057553008036
:100A60009B3018C93092298043501E120CAEEA60A8
:100A700030B4030A205A12D25A1213157403120DFD
:100A8000428006EA20E0E250E2532BFC422B21FC9C
:100A9000C293D295C291E543B4569CC290D2A8802D
:100AA00096305AE5C25A120EA5E480DD7552A0C2F6
:100AB00093D292C20A304102D291E543B45602D297
:100AC00090752E00750600D215754D00120CAEC241
:100AD00089D2A8301E04C22AC21EC25A205646E538


Re: microcontroller ROM copy trouble ?


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Looking hopefull. I dont have any 8051 tools installed so I cant easily
check it, but it looks too regular to be garbage and doesn't repeat in
the ways I'd expect from a bad read.  It dosn't contain any ASCII text
(unless the address and/or data lines are scrambled (not wired 1-1 2-22
etc.)) but I wouldn't expect that unless the original unit has a LCD (or
LED) dot matrix display or a serial port.

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Probably the wrong algorithm. without checking its data sheet, I cant
match it up to a supported device, or are you telling me you tried this
chiptype reading the D23256AC? Unless you have a D23128AC you need to
read, IMHO its not worth the effort.

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*MUCH* the best option if you can get an 87c257 to program.

So you ran out of blank roms :-)  If you are doing much of this, you
*need* a UV EPROM eraser.  Easy enough to make if you can get the UV
tube and a torch with the same size tube to gut for the tube mounting
and invertor. *DONT* look at the light - if you value your eyes (if you
catch a brief glimpse it wont hurt you).  At its  minimum, its just the
tube powered up and supported 1 diameter above the window in the EPROM
in a bit of antistatic foam, with a box over it all so you cant see the
light from the tube.  The timing is important. You need to find how long
it takes to wipe the chip then add about 50% for reliability. I suggest
starting with 3 minute increments. and expect a result in the 10-20
minute range  Once you know how powerful your eraser is, you can just
use that time, but an occasional check for blank at 2/3 time is good
incase yor UV tube is getting weak.  Get this project out of the way
then box up the eraser nicely, painting the inside of the box matt black
and maybe add a timer.

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NO, completely the other way round, make a supported 27C256 look like a
D23256AC or 87c257 so it can be used to *REPLACE* the D23256AC in the
equipment after programming it without the adaptor.


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YES, you need to intercept the high address lines (A0-A7 stay directly
connected) and insert a latch between them and the combined address/data
lines clocked by  the ALE signal.  SMD TTL octal latch chip, some very
fine solid core wire and get at it.  N.B. when building SMD 'dead bug'
fashion, solder all the kynar (wire wrap wire) to the chip pins first.
You will probably need a bit of very thin stiff plastic to glue the chip
to.  The  plastic is glued on top of the frame of the lower socket. You
cut back the pins of the top socket that you need to divert and solder
the wires to the stubs.  You solder all the pins left on the top socket
with the top socket not quite fully inserted into the bottom one. do
corner pins first and get it level. The actual sockets on a turned pin
socket take solder quite nicely but you only get one shot to put a pin
in there. Put the bottom socket in another one or some scrap perfboard
while you work to stop the pins moving if the plastic softens from the
heat. Lay off the Coffee for 24 hours before hand and get a good nights
sleep first!

It *MAY* be possible to get away with a normal flat pin socket with the
high address pins bent out and patched to the outputs of one of the
octal latches on the board if the address demultiplexing for the RAM has
its outputs permanently enabled (or pick it up at the RAM).  If the
latch has a chip other than the 8051 feeding /OE or CLK, its probably no
good for the signals you need. Pin 20 would need to be tied low.
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<IntelHEX dump snipped>

I recccomend you find a file sharing service to post the dump to then
give us a link for anyone with 8051 experience can then take a look at
it.  It would be nice to know make model and description of the unit you
are trying to repair as well.

Good luck with it, I admire your persistance
HAPPY NEW YEAR.

P.S. I have a new year resolution for you: If it aint broke dont fix it!
(Unless you can afford to sacrifice one to your curiosity)


--
Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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Re: microcontroller ROM copy trouble ?



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is intended
programmer supports

[trim -- lots of very helpful advice]

Thanks Ian,

For all the help and useful advice.
I forgot to thank you for taking time and effort to help.
I do appreciate all the help.

Now, still waiting for new ROMs to try out all the advice.

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to then
look at
unit you

Ah persistance,  well i have always enjoyed challenges of big
problems, trying to figure out how things function and
elegant/simple solutions.

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dont fix it!
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I guess  the original problem was not challenging enough to
supress curiosity?

This project  happened to be affordable, i usually check
cavalier at the door where affordability is a dominant factor.


thanks again for all the help,
robb



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NUL:


Re: microcontroller ROM copy trouble ?




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The address is obviously being latched in the ROM. Otherwise, when the
8051 switches to reading the ROM's data, the address that it was
providing to the ROM will be gone.

Re: microcontroller ROM copy trouble ?



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       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I was wondering about that.

I have not found a data sheet for the D23256.

Is the OP trying to insert a 27256 into the same socket that the D23256
came out of ??

That would explain why the 27256 would not work in the same socket.

donald

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Re: microcontroller ROM copy trouble ?



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when the
the D23256
socket.
was

Hello OP here,
The reason for trying to use a 27c256 in place of the D23256AC
is.....

 that was some advice given on the MCU-Mall user forum where they
sell lots of cheap chinese ROM programmers.

one of the regular posters thought 23256 was just a read only /
mask rom version   of the 27c256 ?
so i went with that.

i kind of half convinced myself that the latching mechanism could
be superceeded with a fast enough 27c256 operation ????

the 23256 was 150ns and many 27c256 are 50-90 ns so that 27c256
is ready long before the read occurs ??? that was my thinking


thanks for any help ,
robb

robb



Re: microcontroller ROM copy trouble ?



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For such a scheme to possibly work, your replacement ROM has to be a
lot slower, not faster. A 150ns ROM means the MCU has to wait at least
150ns before the data is valid for reading. A 90ns replacement ROM
means the data is guaranteed to have changed at most 90ns after an
address change, long before the MCU is set to read it.

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Re: microcontroller ROM copy trouble ?



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Andy,

I do not believe this is 100% correct.

You are correct that the data is stable 150ns or 90ns after the Chip
Select line is stable. The data will stay stable as long as the CS line
and address lines are stable.

The CPU involve is an 8051. The date of the circuit the OP has (1985) is
old enough to believe that it is a 12Mhz processor with an internal
divide by 12.

So the memory cycle time of the CPU is 1us, the cpu will "wait" most of
that 1us before it latches the data from the ROM.

I'll check an old 8051 data sheet later, but a 90ns ROM will work just fine.

doanld

Re: microcontroller ROM copy trouble ?



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to be a
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at least
replacement ROM
after an
Chip
CS line
(1985) is
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internal
most of
work just fine.
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Donald,
you are correct about the 8051,  it is running at 12Mhz .

and in case i have not mentioned before the D23256AC lines/pins
are consistent with the 27c256 in terms of conections made to the
8051

now i am just awaiting new mouser  ROMs to test the new style
ROM reads that look like real code.

no readable ascii strings such as copyright strings or company
name  in the new style  ROM reads though ?? so that has me still
a little suspicious but as code the new ROM download actually
runs and loop in an 8051 simulator so that is promising.

Thanks for all the help donald,
robb




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