After fixing the 7405 inverter issue - I decided to use the Diagnostic ROM Pack to check the CRC for three 4052 cartridges I purchased from Stan back in 2000.
One cart was labeled Character & Symbols, and two said FFT2 on the label on the end - however one of those had an NII label where I had handwritten a note that it was a 4907 File Manager cartridge for 4052/4054!
I turned off power - plugged a cart in slot 2 with the Diag Cart in slot 1 - configured to run the ROM CRC test
I then turned on power and the ROM CRC test would immediately run. If the unit was off very long, the text would not be clear and I would quickly cycle the power.
The additional ROM Cartridge CRC would be listed after the Diag ROM CRC - as shown in these screenshots:
Character & Symbol:
View attachment 45653
FFT2
View attachment 45654
4907??
View attachment 45655
Sure enough the Character & Symbol checked OK and the FFT2 was OK, but the suspicious cart CRC was not the same as the published 4907 CRC.
I opened that cartridge and the board said "16K ROM Pack"
Here are photos of both sides of the board and my handwritten note on back of the cartridge:
View attachment 45650
View attachment 45651
View attachment 45652
I then downloaded the bitsavers 4907 User Manual - and tried a couple of the CALL statements in the test program on page 4-1: CALL "TIME",R$ and CALL " UNIT",1 and CALL "DRES",1
without any cartridges plugged in - those were all invalid CALLs
with the suspicous cart - the last two calls just returned with no errors. The CALL "TIME" returned with a GPIB error.
So that cart might have valid 4907 code - maybe early development code?
Monty