VOGONS


Zenith Z-433 D Password

Topic actions

Reply 20 of 23, by rasz_pl

User metadata
Rank l33t
Rank
l33t
fearangel wrote on 2026-09-16, 21:34:

Problems: I can't disable the password in the menu. With the pins shorted, the menu doesn't open "security - password mode..."

does it open option 1?

fearangel wrote on 2026-09-16, 21:34:

Is it possible to solder the pins and leave it like that forever?

sure, shorting does same thing as removing chip, in both cases machine doesnt see it at all

fearangel wrote on 2026-09-16, 21:34:

Another problem: I made a bootable floppy disk to access the BIOS

what do you mean by "access the BIOS"? BIOS is build in.

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/Zenith_ZBIOS Zenith Z-386 MFM-300 ZBIOS disassembly

Reply 21 of 23, by The Solutor

User metadata
Rank Member
Rank
Member
rasz_pl wrote on 2026-09-17, 02:41:

sure, shorting does same thing as removing chip, in both cases machine doesnt see it at all

From the machine POV, sure. From the chip POV, likely, but I wouldn't be 100% that the chip initializes itself, after the short, exactly in the same way it does when powered on.

Reply 22 of 23, by rasz_pl

User metadata
Rank l33t
Rank
l33t
The Solutor wrote on 2026-09-17, 03:00:

From the chip POV, likely, but I wouldn't be 100% that the chip initializes itself, after the short, exactly in the same way it does when powered on.

? Re: Zenith Z-433 D Password "i2c is open collector thus devices can only pull pin voltage to ground"
pulling to ground completely disables I2C communication

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/Zenith_ZBIOS Zenith Z-386 MFM-300 ZBIOS disassembly

Reply 23 of 23, by The Solutor

User metadata
Rank Member
Rank
Member
rasz_pl wrote on 2026-09-17, 03:12:
The Solutor wrote on 2026-09-17, 03:00:

From the chip POV, likely, but I wouldn't be 100% that the chip initializes itself, after the short, exactly in the same way it does when powered on.

? Re: Zenith Z-433 D Password "i2c is open collector thus devices can only pull pin voltage to ground"
pulling to ground completely disables I2C communication

Like I said I have no doubt about that, what I mean is that there could be a sort of internal initialization when the chip is powered, that may not happen when the IC is re-enabled using the shorting way. I've seen chips that behaved differently in cases like this even if they are the same IC type, but from different brands or even generations. That was common on CPUs or microcontrollers, but sometimes happens on ICs that aren't even digital

https://hackaday.com/2026/06/03/texas-instrum … tible-versions/

Behavior is predictable when you stick to supported scenarios, but not guaranteed when you don't, and shorting two pins hardly can be defined as a supported scenario.