HP Forums

Hi Guys, for several years, I am seeking a scientific calculator with a big screen and keyboard and never found one, so I decide to make a retro one. the simple way is using a calculator ASIC and connecting it to LEDs and a mechanical keypad. Unfortunately, there are too few chips with LED output directly, so I should make a LCD to LED converter first. After doing the first test, it runs OK. It's not an emulator but a "real" machine. Here is the prototype of the calculator with the original PCB. The next step is to integrate all the parts into a whole PCB, and add mechanical keys, wish you like it.

and here is a short video:

That's pretty nice. Maybe add a macropad for the keys. Will it be RPN?

the 1st integrated pcb worked finally.

https://flic.kr/p/2oxYuAn

(05-04-2023 03:11 PM)geekvan Wrote: [ -> ]the 1st integrated pcb worked finally.

If you ever sell a kit, I'm in!

(05-05-2023 02:49 AM)toml_12953 Wrote: [ -> ]

(05-04-2023 03:11 PM)geekvan Wrote: [ -> ]the 1st integrated pcb worked finally.

If you ever sell a kit, I'm in!

Thanks, but I'll make this project open and won't sell it.

here is the final prototype without enclosure.









https://www.youtube.com/shorts/Iv_z6_ydeSI

all the sources can be found here:
https://github.com/geekvan007/retro_sharp506

Very nice indeed! Does the calculator chip have to come from a salvaged calculator?

(05-13-2023 01:53 PM)EdS2 Wrote: [ -> ]Very nice indeed! Does the calculator chip have to come from a salvaged calculator?

Yes, The chip named SHARP-LI3301A from last century.
Thanks!

Aha - looks like quite a few manufacturers used that chip (Edit: but these are programmable, which is confusing me):

Quote:Used in: ASTOR: 2, ATABA: AT687, AURORA: TB607, CANON: F300, CITIES: 8700, CITIZEN: SRP145, CITIZEN: SRP40, DYNA-TONE: G3/8700, IBICO: 098, INTERTRONIC: SC88P, KNIGHT: K31A, MBO: 610PR (version-1), MBO: 820PR, PIRACOMP: PR40, PIRACOMP: PR80, PRIVILEG: LC650PR, RADIO SHACK: EC4021, RADIO SHACK: EC4036, WHIRLPOOL: CW201

Also apparently Levis and Shangji.

Edit: is it the 42-key SHARP EL-506P we need? I see there was a 506A and 506H too, with different number of keys.

If so, there's a list of 20 clones here.

Edit: this is confusing!

Quote:With the replicas of the chip used in EL-506P, the first „clones” was built in similar housing as used in EL-506H, at various factories in Hong Kong, Taiwan and China. Later, with similar appearance and same model number, a simple programmable calculators based on a genuine Sharp chip — which was made for Sanyo — completed.

(05-13-2023 03:03 PM)EdS2 Wrote: [ -> ]Aha - looks like quite a few manufacturers used that chip (Edit: but these are programmable, which is confusing me):

Quote:Used in: ASTOR: 2, ATABA: AT687, AURORA: TB607, CANON: F300, CITIES: 8700, CITIZEN: SRP145, CITIZEN: SRP40, DYNA-TONE: G3/8700, IBICO: 098, INTERTRONIC: SC88P, KNIGHT: K31A, MBO: 610PR (version-1), MBO: 820PR, PIRACOMP: PR40, PIRACOMP: PR80, PRIVILEG: LC650PR, RADIO SHACK: EC4021, RADIO SHACK: EC4036, WHIRLPOOL: CW201

Also apparently Levis and Shangji.

Edit: is it the 42-key SHARP EL-506P we need? I see there was a 506A and 506H too, with different number of keys.

If so, there's a list of 20 clones here.

Edit: this is confusing!

Quote:With the replicas of the chip used in EL-506P, the first „clones” was built in similar housing as used in EL-506H, at various factories in Hong Kong, Taiwan and China. Later, with similar appearance and same model number, a simple programmable calculators based on a genuine Sharp chip — which was made for Sanyo — completed.

It seems that the chip LI3301A is used for OEM manufacturers only. All SHARP calculators that use this chip are clones (fake). I bought many used calculators with this chip that have different suffixes, including 506P/506H/514.

Also, I heard that this chip has a clone one which was made by a Vietnam company.

I sure like those keys.

Looks great and thanks for sharing your project.

But one feature is distracting and it is the blue LED MEM indicator.

Geekvan,
Who's the source of your keytops? And standard Cherry keyswitches?

Bill

(06-18-2023 04:35 AM)bwiese Wrote: [ -> ]Geekvan,
Who's the source of your keytops? And standard Cherry keyswitches?

Bill

Hi Bill,

keytops were bought from China Taobao: blank xda and printed xda number keys.

https://item.taobao.com/item.htm?id=676692151586
https://item.taobao.com/item.htm?id=685502367565

and the key is compatible with Cherry MX.