Welcome to ComputerHobbyShop.com   Click here for a ChatGPT 4 Summary of this Website. I ran PowerBook 1400c modified upgrade memory board tests today. The boards were modified for me by CayMac Vintage who also did my SE/30 board reload. The tests were for 2 modified upgrade RAM boards, each tested separately.     My plan was for the 2 memory expansion boards to be increased from 8 MB each to 24 MB each and use them together for a total of a 48 MB upgrade and with the 16 MB already in the factory specs that should equal 64 MB total. I now have partial success in the test results which were a little surprising. I labeled the 1st modified upgrade board #1. It used to have 8 MB, whereas it supposedly now has enough chips to be a total of 24MB. It boots with Error Message at start up. It will finish booting but still only shows 8 MB. It seems the Powerbook 1400c can see there is more memory but due to a testing error, cannot pass the test of it all during the startup memory testing phase. The 2nd modified upgrade board I labeled #2 also used to have 8 MB, and it supposedly now has enough chips to be a total of 24 MB as well. It will boot without any error at startup but after booting only shows 16 MB and works OK with my onboard memory for a total of 32 MB. It seems the Powerbook 1400c can count twice the RAM than before on board #2, but it cannot count all the RAM during the startup memory testing phase, and possibly it ignores any discrepancy altogether so I get no error message at all. The fact that I got double the memory and no error during the test phase means we were on the right track, and only one-third of the RAM is not being detected at all. Results: All I can get working right now is 24 MB total using only modded expansion board #1... ... OR ...32 MB total using only expansion board #2, which is the same total I got using both 8 MB boards before the modifications. At present, I cannot install both modules at the same time as the height is too much. It seems the Apple factory-supplied upgrades must have come with half-height RAM chips, (something I did not know before). Not knowing about the space available beforehand made buying full-height RAM my mistake. Also, today I saw this 1400c with 64 MB on eBay, which is very rare as it has the total possible upgraded RAM already. I would buy it if possible even just to learn what the official upgrade looks like, but sadly, if you ever see a memory upgrade like it has, the prices seen just for upgrades seems crazy & simply insane! For now, I'm inviting everyone to CayMac Vintage to see Will Jacobs page at ko-fi.com/caymacvintage I'll try more later but for right now this is just the current Powerbook memory test results. With the holidays almost here, I'm out of time to work on the SE/30 reload that was sent back to me but I will get to it later. I'm very thankful for the help from Will Jacobs and wish to again say happy holidays! See my top project right now at computerhobbyshop.com/#Top_Projects eol