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Calculator Modifications =>
Calculator Hardware, Electronics, Robotics
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Jacobbus
Member
Joined: 20 Aug 2005
Posts: 106
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 Posted: 27 Dec 2005 11:35:54 am Post subject: |
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Not long ago I found a 512k ROM chip. Documentation is here: MSM27C402CZ
I thought it was posible to use this as external mem for my calc.
But to do this I need to translate the serial signal from the linkport to some kind of 8/16 bit binary signal to put it in 8/16 ports of the chip.
I gues that if you send something out the linkport in asm, lets say the 8 bit number 17 the linkport wil output 00010001 just after each other with a constant time between each bit.
So the signal needs to be modified to a 0 to port 8 an 0 to 7, 0 to 6, 1 to 5 ,0 to 4, and so on.
The question is: are there elektronics that do this for you? or do I have to use smal microcontrolers and that kind of stuff?
Last edited by Guest on 27 Dec 2005 11:38:00 am; edited 1 time in total |
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kermmartian
Site Admin Kemetech
Calc Guru
Joined: 20 Mar 2004
Posts: 1220
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| Posted: 27 Dec 2005 01:43:46 pm Post subject: |
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You'd have to get leads directly soldered onto the 9 bus lines (8 bits + gnd), which would NOT be fun.
If you did it via the linkport, you'd need a PIC and a prog on the PIC to buffer eight bits from the link port and send them all at once to the chip; for the other way, break down each byte and send it bitwise. You'd also need a program on the calculator to read whatever file system you came up with.
Last edited by Guest on 27 Dec 2005 01:45:42 pm; edited 1 time in total |
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Jacobbus
Member
Joined: 20 Aug 2005
Posts: 106
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| Posted: 27 Dec 2005 02:59:05 pm Post subject: |
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oke, thanks I Think I'l be able to buy a PIC.
Never before worked with PIC's, but heard of them before.
can you program them in asm and how much do they cost, inc. the stuf to link up with a pc? |
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DigiTan
Unregistered HyperCam 2
Super Elite (Last Title)
Joined: 10 Nov 2003
Posts: 4468
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| Posted: 27 Dec 2005 10:32:24 pm Post subject: |
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| They usually run about $3 U.S., plus overhead for the programming cable and additional parts. The ASM looks a lot like TI ASM, in fact I'd say it's easier to work with--for various reasons. |
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Raster
Active Member
Joined: 17 May 2004
Posts: 529
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| Posted: 29 Dec 2005 01:35:48 am Post subject: |
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I tryed doing something similar to this (It was an EPROM burner project, thinking about bringing it back). I though about using a 74HC164 8 bit serial to parallel, and a 74HC165 8 bit parallel to serial CMOS chip. I dont think you can series the 74HC165, but you can the 74HC164 (meaning you can have as many data outputs you need). All you need it to do is send the adrress bus data out of the calc, and then input/output the 8 bit data, wether you want to save data, or receive data. So that mean you dont need to series the 74HC165. It is a standard Clock-Data serial, so itll be easy to make, and program the calc.
Ill try to rescan the EPROM burner schematics for you, as a refference. If you want any more info, Id be glad to answer your PM's/emails.
Last edited by Guest on 29 Dec 2005 01:41:16 am; edited 1 time in total |
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Raster
Active Member
Joined: 17 May 2004
Posts: 529
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| Posted: 29 Dec 2005 03:41:26 pm Post subject: |
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Sorry for the double post, but I want people to relize, there is a new post!!! I found the schematics, so here they are!
EPROM Burner Serial-parallel translator
EPROM Burner RAM banks
[EDIT]
No comments? How sad  .
Last edited by Guest on 30 Dec 2005 03:54:13 pm; edited 1 time in total |
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