I was pretty sure z80's were only a couple of cents...well maybe that's just how much it takes to produce them...

I was pretty sure z80's were only a couple of cents...well maybe that's just how much it takes to produce them...

Yes.  I'm pretty sure you are correct.  I was quoting the retail price.  

Why do they charge $115 for the calc, though?  It was even more than the Prizm at my local Office Depot!

Hi everybody! I'm new here I'm starting to learn z80 assembly for the ti 83+. I was wondering if it would be possible to build your own calculator with a z80 microprocessor and some sort of screen similar to the ti calculators screen. Wouldn't you have to put the ti-os on it to run programs and such? If this is even possible we could probably add more memory to the home made calculator. Unless that would cause you to have to rewrite the ti os or something to support more memory. I don't know if this is just stupid or if some one has asked before. But all feedback is appreciated!  (Sorry if this is dumb or impossible)

Welcome here! In answer to your questions:Yes it is possible. TI-OS is not a prerequisite, just anything that would run on whatever Z80 you choose. I'd also suggest checking Ben Ryves's topic linked to on page one. Although his is a computer, it is built on a similar idea.

Hey, would you rather want to work together on this project? We could meld together DreamCalc and whatever you'll call this...

@Spyro543 Yeah I would work together with you, if you think you can and know how to build it because I want someone who would be dedicated to this and could give me their input and skills. Also will you show this Dream Calc idea thing your talking about?

So guys I'm putting together a list of stuff I might need to make this thing. Feel free to suggest different places to buy  stuff and if you think I should add anything.

Z80 - http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&pa=35561&productId=35561&keyCode=WSF&CID=GMC

128K flash rom - for os   using rom because it would not be rewritten alot

Do you guys think I should use eeprom

or

sd card? - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=WM3472DKR-ND

64k ram chip - ?

LCD - ?

i/o chip - ?

You guys are going to have to help me with this thing because I know your all super geniuses and stuff and I, no we will build this thing together so how about it? Will we build this thing for all the nerdy people who want an affordable calculator with a lot of memory!?

PIO is annoying with discreet logic ics. To use more than 64k memory (ram+flash) you need to do bank switching. The easy way is to use a microcontroller for io and use 8 bit latches (74HCT259) to hold the higher bits of the address. I recommend using an eeprom or sd card. It would be nice to store data somewhere other than ram and to upgrade the os. If you want to use an sd card, you need a way to convert the z80's 8 bit parallel data to an spi signal. An FPGA could be an option for io but you'll need to use a small microcontroller like a pic to load the configuration to the FPGA on startup. For ram, you should use sram because it doesn't need to be refreshed so you can "turn off" the calculator and still have a small current going to the sram so you don't need to setup ram every startup.

You should make it support BBC Basic.

That is all. Then we can have cross-platform progs.

Ooh PIC chips! A friend of mine knows all about PIC ASM!