Author Topic: Build your own Z80 calculator  (Read 20261 times)

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Offline Eeems

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Re: Build your own Z80 calculator
« Reply #15 on: September 26, 2011, 12:21:41 am »
I was pretty sure z80's were only a couple of cents...well maybe that's just how much it takes to produce them...
/e

Offline DJ Omnimaga

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Re: Build your own Z80 calculator
« Reply #16 on: September 26, 2011, 12:24:42 am »
I think the money issue is more when it's time to produce the units in batch then market them. I could be wrong, though.

Offline ralphdspam

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Re: Build your own Z80 calculator
« Reply #17 on: September 26, 2011, 12:25:53 am »
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!
« Last Edit: September 26, 2011, 12:26:08 am by ralphdspam »
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Offline Netham45

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Re: Build your own Z80 calculator
« Reply #18 on: September 26, 2011, 01:54:22 am »
Why do they charge $115 for the calc, though?  It was even more than the Prizm at my local Office Depot!

They pretty much have a monopoly on it, and they're exploiting it as much as they can.
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Offline TIfanx1999

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Re: Build your own Z80 calculator
« Reply #19 on: September 26, 2011, 02:27:01 pm »
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!  ;D (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. :)

Offline kingofthebacon

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Re: Build your own Z80 calculator
« Reply #20 on: September 26, 2011, 05:25:03 pm »
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!? :)

Offline Spyro543

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Re: Build your own Z80 calculator
« Reply #21 on: September 26, 2011, 05:30:54 pm »
Hey, would you rather want to work together on this project? We could meld together DreamCalc and whatever you'll call this...

Offline turiqwalrus

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Re: Build your own Z80 calculator
« Reply #22 on: September 26, 2011, 05:47:09 pm »
Why do they charge $115 for the calc, though?  It was even more than the Prizm at my local Office Depot!

They pretty much have a monopoly on it, and they're exploiting it as much as they can.
meh... my school REQUIRES TI's
[/offtopic]
sounds really cool; another indpendent calc project ;D

Offline kingofthebacon

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Re: Build your own Z80 calculator
« Reply #23 on: September 26, 2011, 06:06:09 pm »
@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?
« Last Edit: September 26, 2011, 06:06:23 pm by kingofthebacon »

Offline Spyro543

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Re: Build your own Z80 calculator
« Reply #24 on: September 26, 2011, 06:59:39 pm »
@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.
Well, we could work together building it...I guess.

Also will you show this Dream Calc idea thing your talking about?
http://ourl.ca/12651 Here's the link to the thread, but almost all discussion was done on IRC.

Offline Camdenmil

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Re: Build your own Z80 calculator
« Reply #25 on: September 26, 2011, 11:02:39 pm »
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.
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Offline ralphdspam

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Re: Build your own Z80 calculator
« Reply #26 on: September 26, 2011, 11:20:52 pm »
I think you should have the OS on EEPROM or Flash and data on the SD card.  You can then copy the program from the SD card and then execute it from the SRAM.  
« Last Edit: September 26, 2011, 11:21:09 pm by ralphdspam »
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Offline willrandship

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Re: Build your own Z80 calculator
« Reply #27 on: September 26, 2011, 11:26:06 pm »
You should make it support BBC Basic.

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

Offline kingofthebacon

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Re: Build your own Z80 calculator
« Reply #28 on: September 27, 2011, 05:08:12 pm »
So I should add this to the list

8-bit latches http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-2109-5-ND

Would this pic chip work?? - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PIC16F57-I/SS-ND

32k sram two of these chips - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=BN-064HSRC-ND

Would this fpga chip work?? - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=TMPA900CMXBG%28EY%29-ND

Can I hold the OS on the sd card?
I would need some sort of programmer to program these I don't want it to be too expensive though.
I'm not the best with digital electronics either so I am going to need some help from you guys!
Without all of you this will only be a dream...

Offline Spyro543

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Re: Build your own Z80 calculator
« Reply #29 on: September 27, 2011, 05:10:25 pm »
Ooh PIC chips! A friend of mine knows all about PIC ASM!