Expansion storage board

What have you built or do you want to design to go with your replica 1

Expansion storage board

Postby S_Parkinson » Aug Wed 15, 2012 8:20 pm

Hey everyone, i was looking at making an expansion board that would allow me to store programs i write in basic, Has anyone already attempted this, or has any schematics do do with this?
Any help is greatly appreciated
Cheers
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Re: Expansion storage board

Postby tranter » Aug Wed 15, 2012 10:34 pm

By "expansion" what did you have in mind - EEPROM. flash memory, cassette tape?
There's a simple RAM/EEPROM circuit documented here http://www.brielcomputers.com/eeprom.pdf. I built a 16K memory board based on that circuit but it doesn't provide a lot of storage.
The CFFA1 is a 16MB flash board for the Apple 1 / Replica 1 but the design is pretty complex to build. You might be able to find someone selling a used CFFA1 board.
Vince is doing a run of Apple Cassette Interface boards if that would meet your needs.
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Re: Expansion storage board

Postby S_Parkinson » Aug Wed 15, 2012 11:12 pm

Looking at EEPROM, i was contemplating getting one of the cassette expansions boards, however i was hoping to do somehting more " home made "
Thanks for the link and quick reply :)
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Re: Expansion storage board

Postby S_Parkinson » Aug Wed 15, 2012 11:19 pm

Also, what would i have to do in terms of software to be able to safe to the expansion EEPROM? :)
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Re: Expansion storage board

Postby tranter » Aug Thu 16, 2012 8:30 am

The software could be as simple as some code (even in BASIC) to copy from the Replica 1's RAM to the EEPROM.
You could get fancier if you wanted to implement some kind of file system.

You might be interested in this design too:
http://school.anhb.uwa.edu.au/personalpages/kwessen/apple1/extensions/extensions.html
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Re: Expansion storage board

Postby S_Parkinson » Aug Fri 17, 2012 5:01 am

Just to check, the link you posted originally ( http://www.brielcomputers.com/eeprom.pdf ) you just match up the labled circuit lanes, to the ones in the 40 pin expansion area?
Cheers
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Re: Expansion storage board

Postby S_Parkinson » Aug Fri 17, 2012 5:03 am

and would this EEPROM chip be ok to use? :) http://australia.rs-online.com/web/p/ee ... s/0394504/
just that this is really one of the very few I am able to get my hands on. Thanks :)
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Re: Expansion storage board

Postby tranter » Aug Fri 17, 2012 9:04 am

Basically, yes.

The board I built supports 2 8K EEPROM. EPROM, or RAM chips. See https://github.com/jefftranter/6502/tre ... emoryBoard

That ATMEL EEPROM should work. I had success with ATMEL devices. I had problems with a XICOR chip.
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Re: Expansion storage board

Postby S_Parkinson » Aug Mon 20, 2012 2:35 am

Just needed some help,
Where the n/c ( pin 1 ) on the EEPROM chip connect to?
on the 74LS00, where do i get the phi2 ( i assume its the 5mhz one on the replica one ) connection from?
Are the DQ0-7 the same as D0-7
Am i correct in assuming that the vcc is =5v?

Sorry for all the questions, im just wanting to make sure, so i dont accidently break something

Cheers :)
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Re: Expansion storage board

Postby tranter » Aug Mon 20, 2012 7:57 pm

> Just needed some help,
> Where the n/c ( pin 1 ) on the EEPROM chip connect to?

It does not need to be connected to anything.

> on the 74LS00, where do i get the phi2 ( i assume its the 5mhz one on the replica one ) connection from?

It comes from pin "A" on the expansion slot.

> Are the DQ0-7 the same as D0-7

Yes, that is correct.
Keep in mind that some EEPROM data sheets list the data lines as I/O1 through I/O8 (i.e. starting at 1 rather than zero) so in that case be sure to connect I/O1 through I/O8 to D0 through D7, respectively.

> Am i correct in assuming that the vcc is =5v?

Yes.
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Re: Expansion storage board

Postby S_Parkinson » Aug Tue 21, 2012 5:26 pm

How does this look?
Attachments
eeprom.PNG
eeprom.PNG (58.77 KiB) Viewed 17941 times
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Re: Expansion storage board

Postby tranter » Aug Wed 22, 2012 9:43 am

It looks good. I didn't check all of the wiring. A few comments:

- You can expand this to support 2 EEPROM chips if you do some more address decoding. The board I built does this. I gave a link to the design files earlier.
- The circuit will also work with 6264 type RAM chips. I sometimes use my board with EEPROMs and sometimes with RAM.
- It's good practice to use power supply bypass capacitors - typically one 0.1uF between VCC and ground for each IC. A larger bypass cap, e.g. 10uF across VCC and ground is also a good idea (one per board).
- I found it useful to provide a jumper or switch to enable or disable writing. That way you can protect the EEPROM from writing if you are concerned that a bad program could corrupt them.
- There are veroboards available that have the edge connector that fits the slot on the Replica 1. Is that how you were planning to build this?
- If you expect to change the EEPROM chips regularly a ZIF socket might be a good idea.
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Re: Expansion storage board

Postby S_Parkinson » Aug Wed 22, 2012 5:15 pm

Thanks again, for all the help :)
I was using the veroboard, just because i have alot lying around, i was just going to use an old pata cable to bring the 40 pin expansions lanes, to the board.
Ahh ok ive got quite a few cap's lying around so il install a few of them.
And ill take a look at your design, and see what i am able to do with it :)

Thank you for all your help :)
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