Horizon VAC-100 Firmware Compatibility Issue - Help Needed with v1.2 and v5.0 Mixed Configuration

[MinaevDV]

Hello everyone,

I need help with a firmware compatibility issue on my Horizon VAC-100 collator system.

CURRENT CONFIGURATION:
• Line 1: Two towers running firmware v1.2 (M27C1001 chips) - working fine
• Line 2: Two towers running firmware v5.0 (M27C2001 chips) - working fine

THE ISSUE:
I want to ADD a third tower (v1.2) to Line 2 (which currently runs v5.0 on 2 towers).
When I connect the v1.2 tower to the two v5.0 towers, the system malfunctions:

✗ Bins 1-3 rise up automatically when powered on
✗ Trays do not respond to control commands properly
✗ System appears to have incompatible firmware communication
✗ No error codes displayed, but system clearly fails

PROBLEM ANALYSIS:
After analyzing both firmware files:
- v1.2 and v5.0 are COMPLETELY different (95% code differs)
- Horizon International discontinued VAC-100 support years ago
- Official distributors confirm firmware is NOT available for supply anymore

MY QUESTION:
Does anyone have experience running mixed firmware versions on VAC-100 towers in the same line?
Specifically:
- Can three towers with different firmware versions (2 x v5.0 + 1 x v1.2) communicate properly?
- Is there a firmware v5.0 version compatible with M27C1001 chips (128KB)?
- Has anyone successfully resolved this compatibility issue?

ADDITIONAL INFO:
- I have both firmware files (v1.2 and v5.0)
- I can program EPROM chips with TL866 programmer
- Official service is unavailable (Horizon discontinued VAC-100 support)

Any suggestions, workarounds, or shared experiences would be greatly appreciated!

Thank you!