48G mod. after 15 years.



Though I have an HP 50g, I've repaired the 15 years old 48G from a kind of sentiment and nostalgia recently.

Then upgraded its memory to 128KB and additional 128KB with memory backup at port 1.

Actually, I prefer 48G's key pads than that of 50g.



Is it possible also to implement 50g-Rom?


AFAIK, It's impossible as the processor differs.


As always,

fantastic work and explanation.

2 months ago I received a non working 49g , took its display and installed it into my 48G+ and changed also the cap...

full 48 working machines :)



Thanks Nacho,

I'd like to see the LCD transplantation.

It's also interesting.

Is the LCD of the 49g completely compatible to 48g?




Thanks Nacho,

I'd like to see the LCD transplantation.

It's also interesting.

Is the LCD of the 49g completely compatible to 48g?



Hello Lyuka,

The display is P&P but far better with the high 49g contrast.

I will post a picture later.



Absolutely impressive!

Was it difficult to open the case?

And, the holes are CLEAN after you desoldered and removed the chip and capacitor! Very neat job.

I suppose this was not done with tools normally found at home, right?


Thanks Ed,

It's fairly easy to open the case if you use a special tool for the 'pioneer' ---


To pull out the four heat stakes behind the [1][2][3] keys,

I had used it as a leverage to make the bottom of the case apart.

FYI you'd better have its edge rounded and polished not to harm the inside part of the housing.




Nice work (and documentation).

How did you remove the 32k memory? Did you use chipquik or solder braid?



Thanks TomC,

I used CHIP QUIK SMD (pdf) like ultra low melting point solder to remove the SOP RAM.

FYI it's available online at DigiKey.




I have removed several SOIC package chips safely and cleanly by starting at one corner and heating the pins and the lift it away from the board using something thin like a sewing needle. Usually if you remove heat simultaneous to lifting the pins, you can get away with just running the needle under the pin and by the time it drops again the solder has cooled enough that it does not stick again. Needles work well because they are thin and you can work your way down the case with it, and they don't lift the pin much so as to minimize bending. You could do the same thing with a thin blade but that doe not work so well if the chips are densely packed on the board.


Another great tid-bit to be used one day. Chip Quik! Great idea!


Chip Quik! Great idea!

Sounds like the latest, greatest cookie dough to hit the market!

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