I've tested one of these now and so far so good.
At least a REX still works through the ribbon so the connections are
good and the extra length doesn't break timing or something.
At least not with a 4" cable up to an 8" cable.
I tested 4, 6, 8, and 12 inch cables, (I don't have a 10", maybe they
weren't in stock), and only the 12" cable doesn't work. It *almost*
does. I had ts-dos load up and seem to work fine, but it makes a rex say
"not enough space to install ...", so assuming it's not a bad connection
then the extra length either makes the timing or the signal quality go
too far off.
The 4" is long enough to get out from under the machine for all 3 models
100, 102, 200, and the 8" isn't long enough to reach out any other
directions, so there's not point in using anything but the shortest 4"
cable.
https://photos.app.goo.gl/PHQ1rTQFpPRF6NSh8
Sorry I don't have pics of it doing it's actual purpose, which is
capturing the bus traffic with a logic analyzer, but it's a pain to set
all that up. But just soldering the parts and seeing if a rom or a rex
still works in it was easy at the moment.
--
On 8/3/24 13:09, Me Myself and I wrote:
Hi! Im not usually active in the mailing list, but Ive been reading on
all the cool things people have been doing. I am interested in getting
one of Brian's Molex Socket Bus Taps. Let me know what you need from me
to help make that happen.
-February
On Tue, Jul 30, 2024, 10:23 PM Brian K. White <[email protected]
<mailto:[email protected]>> wrote:
Anyone want one of these?
https://github.com/bkw777/Molex_7880x_bus_tap
<https://github.com/bkw777/Molex_7880x_bus_tap>
I'm going to make one for myself and I don't mind making a few more
along the way, considering "Anyone" is probably just Steve since it
would mostly just be useful for debugging REX and REX-like things.
The two parts are connected by an FFC cable and lets you connect a
logic
analyzer to the option rom socket while something is in operation in
the
socket.
The cable is thin and you can even install the rom door cover and flip
the machine back over and use normally with the rom hanging out to the
side of the machine.
What I want it for is, this doesn't work, but I think it's close, maybe.
https://github.com/bkw777/REX_ATF <https://github.com/bkw777/REX_ATF>
REX Classic and REX# are based on the Xilinx XCR3064XL CPLD. That part
was EOL'ed last year.
This Microchip (ATMEL) ATF1504ASL is a very similar chip, and is still
being made and sold new.
Extra bonus, it's a fully native 5v part, so there is no 3V3 regulator
needed and only one VCC rail to route which makes the pcb simpler.
And I managed to reassign some pins so the jtag pins are not used for
general i/o, so programming is a lot simpler. No more aux power
connection, power cmes from the programmer, no more PORT_EN jumper and
pulldown resistor, just connect the jtag and go.
--
bkw
--
bkw
