thanks Martin for your sharing.
At the end seems the ZX80/81 community don't have any dump specific for the lambda
So a way is spend some time to typing some programs present on ZX-team magazine
and found a way to save.
Interesting try to use the original ULA or a "original" clone not only to fix your unit
but also for use the "standard" character set that in Lambda 8300 that are stored on the ULA C4005
and seems not possible to change just changing the ROM.
But for the Lambda 8300 ULA C4005 noted the pinout different and some address line aren't connected
On C4005 ULA (in according a scheme from Power3000) are used:
A0 A1 A3 A10 A14 A15 (no A2, A4, A5, A6, A7, A8)
On Zx81 are used:
A0 A1 A2 A3 A4 A5 A6 A7 A8 A14 A15
Other differences:
HALT and C signals are connect directly to CPU on L.8300
on ZX81 are present additional components.
pin 39 is connect to Data bus via a 74ls05,
I don't know the reason and seems isn't present a equivalent pin in the ZX81 ULA.
So at the end I believe will be no obvious replace C4005ULA
Meanwhile a got another "Chinese clone" called NF300.
Still need to fix (seems have a short circuit to ground on 12V input)
Is based with the same C4005 ULA (remarked as C4335) and has the ROM
with different boot screen NF-BASIC 1 but with the memory detection has the CAC-3.
Curious the approach for the user port: they have close the slot but they have keep
the pads on the PCB without bring any signals !?!...
https://youtu.be/JJzyjnJ9EiI
