TRS-80 Model I EI question

Hello, all: I'm trying to track-down a mod that Tandy on the Expansion Interface. On one of my early EIs (SN# 000352), there was a 6-pin DIN modification, which someone at one time told me was to correct some erratic signal problems. So, I called Tandy and ordered the EI service manual, but it only applies to the "new" PCB version (units with SNs 035000 or greater). Does anyone have the schematics to the original one and can check pin functions?? Internally, the board is labelled "1700077-C", does not have the green conformal coating, and has the RAM chips right next to the power supply section. Mod 1 is on IC Z17 (LS157), pins 1 and 8 (GND) Mod 2 is on IC Z24 (LS32), pins 4 and 7 (GND) Mod 3 is on IC Z22 (LS367), pins 12 and 8 (GND) Matching the old ICs and pin numbers to the new schematics produces the following: Mod 1 is for the MMUX line, Mod 2 is for WR* and Mod 3 is for INT* Can anyone verify this? ------------------------ Rich Cini/WUGNET - ClubWin Charter Member (6) - MCPS Windows 95/Networking