nec (up)d1877c, the unknown "cpu".

[RetroGamerCX]

hi, i remember getting a 1977 (?) calculator (casio h-1) back in 2017-2018, and after many years letting it get dusty, i decided to disassemble it now. i already disassembled it before twice, the first time was to fix it, and the second time was to extract some components, but after a while i decided to assemble it back. yesterday however, i decided to remove the vfd display and the cpu only, because these are the most important parts for me. however, i tried looking up for any datasheets on the internet, and got no valid results... i only got links to some websites selling this cpu, but even those websites don't show any datasheets at all...

 

[Nigel Goodwin]

hi, i remember getting a 1977 (?) calculator (casio h-1) back in 2017-2018, and after many years letting it get dusty, i decided to disassemble it now. i already disassembled it before twice, the first time was to fix it, and the second time was to extract some components, but after a while i decided to assemble it back. yesterday however, i decided to remove the vfd display and the cpu only, because these are the most important parts for me. however, i tried looking up for any datasheets on the internet, and got no valid results... i only got links to some websites selling this cpu, but even those websites don't show any datasheets at all...

As it long predates the internet, why would you imagine you would fine datasheets on-line?. If they existed at all, they would most likely just have been paper copies, in the hands of a few developers?.

 

[danadak]

You sure its D1877C ? You have the digits in correct order ?

The more complete part number would be UPD1877C.

Take a look over here see if its in any of these databooks :

Index of /components/nec/_dataBooks

Regards, Dana.

 

[rjenkinsgb]

The uPD1877C is a dedicated LSI calculator IC, rather than a CPU type device.
A single chip logic version of a calculator built from just simple logic ICs, in other words.

CALCUSEUM NEC_parts(E): D1877C (CalcChip)

 

[RetroGamerCX]

> You sure its D1877C ? You have the digits in correct order ?
yes, here's a pic of it:
> As it long predates the internet, why would you imagine you would fine datasheets on-line?.
6502: am i a joke to you?
> If they existed at all, they would most likely just have been paper copies, in the hands of a few developers?.
maybe...
> The uPD1877C is a dedicated LSI calculator IC, rather than a CPU type device.
oh, so maybe that's why there aren't any datasheets on the internet...

 

[RetroGamerCX]

update:
i'm kinda confused now, because the chip claims to be a d1877c, but then i grabbed the calculator's main board again and i realized it says it's an upd1877c... are they the same thing or did they just use a slightly different chip?

 

[danadak]

Same thing, D1877C is just a short form P/N put on parts back then.


Regards, Dana.

 

[RetroGamerCX]

oh. also, i couldn't find the chip on the link you sent me.

 

[danadak]

I looked at some of the databooks, also did not find, but ran out
of time to do them all.


Regards, Dana.