Next project: 11/24. Does it need memory?--Memory sad!

Chris Zach cz at
Mon Oct 26 20:31:29 CDT 2020

Ok, so I'm now troubleshooting the memory parity errors in the MS11-L 
memory. And yes, there are bit errors in the memory. I wrote a simple 
program to check the first 64k bank and I've found errors in bit 2 but 
not everywhere but on a predictable pattern of addresses. Interesting, 
possible that one of the address drivers is shot in that particular chip..

Checking the board I can see that most of the chips are ITT chips, 21 
16935 01. However I can also see that this is not this board's first 
rodeo, as several chips have been replaced with ITT chips 8411x 21 14897 
01 models.

Is there an equiv model for these chips that can be found? Looks like a 
16k*1 16 pin MOS ram chip with +12,+5,and -5 voltages (wow!). I guess if 
they can't be found I can pull chips from the parity section and just 
ignore parity but I'd prefer not to desolder/resolder chips.

As they say, it ain't gonna fix itself so I might as well get going on 
it. ;-)


More information about the cctalk mailing list