You have lost me.
If you want to dump or re-write the flexrom, you can just do it it it's
programming adapter.
I thought you wanted to dump the original rom?
And if you want to avoid all the hardware actions while changing the
main rom, that's exactly what REX Classic allows. It's purely software
once you set that up, and even if you botch both primary and secondary
images, you only need to open the option rom compartment instead of the
whole machine to revert to the internal eeprom.
If you have a soic-28 test clip, you *might* be able to program the
eeprom without removing from the machine. Mostly it should be ok, the
board allows the programmer to drive /WE for instance, it's definitely
ok to program the chip directly with a test clip if the board is not
installed in the machine. But but one thing I don't know is, if the
board is installed in the machine, all the pins are connected to the
bus. Mostly that should be ok but one thing I don't know is what happens
when the programmer tries to provide power on the vcc pin? Does it power
up the whole machine? Even with the memory power switch turned off,
which normally kills everything, this would be injecting power to the
rail from a point "inside the walls".
If you're worried about the legs, and you're right that it would be a
pain to repair a loose one after the frame was cut away, I now actually
prefer gold plated plain brass wire.
https://gist.github.com/bkw777/52d85d89eeff8445cc667685d05ea94d
The advantages are,
- just wire, no special shapes to cut off or anything, no single special
supplier
- a few feet makes hundreds of 6mm legs
- the wire is round, so there is no problem with it rotating when
loosened and resoldered
- gold plated
- repair/replacement of a broken leg is trivial
The disadvantages are,
- each leg has to be soldered individually, no one-piece connector or
frame like with a normal pin header
- no simple supplier to point to, it's such a generic thing that there
is no part number or such, except in large quantities from bulk
suppliers. The various suppliers (for small quantities) I've found have
all been transient like Etsy or Ebay links that don't work a year later.
And it's easy to end up with gold colored aluminum wire or brass wire
that isn't gold plated (which starts tarnishing within a year), since no
one selling the stuff is writing their descriptions for electronics use.
I have also gotten wire from aliexpress that was thinner than claimed,
which ends up being too thin and weak despite you buying the correct awg
or mm number.
But if you do get some, then you have a lifetime supply after that.
The preloaded bom carts with the pcbs have the sil leadframes just
because it's an actual part that can be ordered normally along with
everything else, and is both a little cheaper and a little more
convenient to solder than the MillMax or Keystone micro pins which could
also be ordered as part of the bom.
--
bkw
On 11/28/23 13:32, runrin wrote:
This is a good idea, but I've already got my new EEPROM in there and
every time I remove it and put it back in, I get worried I'll break off
one of the legs and have to resolder it.
The leadframes used to make DIP pins on Brian's FlexROM adapter board
work well, but I really don't want to have to replace them when I
inevitably break one off.
Would you use a BASIC script to do this Mike? Just a loop to PRINT each
byte to the COM port?
On Tue, Nov 28, 2023 at 11:45:10AM -0500, Mike Stein wrote:
Why not just dump it out of the M100 directly?
On Tue, Nov 28, 2023 at 9:50 AM Brian K. White <[email protected]> wrote:
On 11/27/23 11:48, runrin wrote:
Do you know if it's possible to dump the original ROM using the
programming adapter for the FlexROM 100?
Maybe.
There are two things to worry about and I'll just think out loud right here.
1
The programming adapter presents a pinout for a 28C256, not a 27C256 or
mask rom. Those are only a couple wires different, but then again, since
it's just for reading, and the read cycle is the same, you could just
tell the programmer that it's reading a 28C256 (force it, override chip
id detection), and that won't hurt the rom.
2
Pin 23. The programming adapter routes pin 27 from the programmer (/WE
if a 28C256 were in the programmer) to pin 23 of the DIP socket, which
is ALE on the LH535618 rom, but the flexrom board connects it to the /WE
pin on the actual 28C256 on the board.
I *think* what you want to do is take a DIP-28 socket and bend out pin
23, connect the bent-out pin 23 to pin 27, put the modified socket into
the programming adapter and then the old rom into the modified socket.
Then tell the programmer to read a 28C256 and ignore chip id. The socket
is just to avoid bending the leg on the old chip.
IE, feed /CE from the programmer to both /CE and ALE on the chip, and
don't connect anything to /WE at the programmer.
But, at that point it's almost simpler to just make the entire adapter
manually with two dip sockets and wires. Especially since it's a
one-off. In that case, use a 27C256 pinout and tell the programmer to
read a 27C256 instead of 28C256.
But if your chip has any of these part numbers, then it's already been
dumped.
https://bitchin100.com/wiki/index.php?title=Model_and_ROM_information
--
bkw
--
bkw
