Wavy 70fd 512k memory upgrade

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By daniel683104

Paragon (1254)

daniel683104's picture

13-10-2010, 00:13

I´m trying to get a tutorial of how to upgrade a wavy 70fd to 512k I have found sme topics on this forum. but the links with the pictures and documentation are broken. Please someone could upload a link or the full tutorial (with pictures) that allow me to do the upgrade.
thank you everybody

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By sd_snatcher

Prophet (3509)

sd_snatcher's picture

13-10-2010, 01:49

Here's the recipe, thanks to Tabajara Labs.

It's in portuguese, but you can use Google Translator or The Fish.

It would be wonderful if someone could design a clean specific upgrade board using this recipe.

By RetroTechie

Paragon (1563)

RetroTechie's picture

13-10-2010, 12:12

If you compare 4464 and 44256 IC pinouts, you'll see that they match up nicely. Therefore better method: solder in 4x turned pin IC sockets in place of original 4464's, bend 44256 pins such that they go to suitable contacts on IC socket & solder. Maybe you need 1 or 2 wires of a cm. or so (per IC), but you don't need a circuit board that way. When done, you'll have a multiplexed address line left over on the 44256's, these can be connected to each other & the relevant pin from T9769 (RA8, pin 47 according to above info, too much bother to check on my own Wavy).

After that you'll have to change some wire bridges (J1102 & J1103 according to above, sounds about right), to set MPSL0 (pin 51?) and MPSL1 (pin 52?) inputs on T9769. These 2 signals can form 4 combinations, which select between 64K/128K/256K and 512K by varying how #CAS1, #CAS2 and RA8 are controlled. To be more exact: one of these inputs controls whether you have 1 or 2 #CAS signals, the other selects whether you have 8 (for 4464) or 9 (for 44256) multiplexed address lines.

Optimal would be if you can check the 44256's before soldering them (eg. in an old 256K/512K external mapper), but if one's bad or you make a mistake, it's simple to cut it out & remove remains from the IC socket. My own Wavy does have an extra circuit board, but that's because I went beyond 512K to 1MB. Still considering to replace with 1Mx4 or 4Mx4 chips some time, if I ever get to fixing the keyboard first... Tongue

By daniel683104

Paragon (1254)

daniel683104's picture

13-10-2010, 12:26

could you do a diagram or pictures just don´t one to make mistakes. thank you

By RetroTechie

Paragon (1563)

RetroTechie's picture

13-10-2010, 13:12

As I wrote, my Wavy FD2 has a custom circuit board (which I'm not gonna pull loose), and 8x 44256 IC's (2-high stacks), so pics of that wouldn't be any help for 512K mods. Just picture a turned pin IC socket (18-pin) in your mind, picture a (20-pin) 44256 soldered on top of that, and then 4 times that next to each other on the board. As long as supply pins & control signals are connected 1:1, it doesn't matter what data line on 44256 goes to what data line on IC socket/board. Same is true for address lines (not 100% sure, but AFAIK Sanyo Wavy FD2 uses a refresh method where row address is a don't care, or the multiplexed address lines contain a 9-bit wide row address). And no doubt those J1102/1103 wire bridges are set the same in my machine as per above instructions.

It's possible to do in reverse order: solder 44256's onto IC sockets first, and then into the board.

By daniel683104

Paragon (1254)

daniel683104's picture

14-10-2010, 18:01

I´m not very expert on these and I don´t have the machine in front of me yet. But let me know If I have understand. Step by step and correct me if I´m wrong. I don´t want to screw the wavy before start use it.

1. Remove the 4464 chips from the main board by de soldering. After that I should have 4 empty spaces for the new memory.

2. Solder at the 4 empty memory spaces a (20 pin) IC socket. At the end I will have 2 pins of each IC socket (8 total) bended out because it is not an actual hole of the wavy mainboard.

3. Solder those 8 pins together using a small wire.

4. Solder a side of a wire to the pin 47 of the T9769 and the other side to one of the IC pins that I have put together on STEP 3

5. As a final Step do the bridge J1102/1103. And my question Here Is? According to the picture I Understand:

a...... The ones marked with number 3 full empty (2 holes)

b..... The ones with number 1 (those at the middle) are join together. I mean number 1 on top with number 1 on botton

c..... the ones with number 2 (those at the right) are joined number 2 at the top with number 2 at the botton

It´s my interpretation Ok?

So this is how I undestand your explanations, are they correct? If it doesn't please corrrect me step by step if you can. Sorry about being so picky but first about the language and second by my short knowledge of electronics I wouldn't like to screw it.

Any help or new Idea will be welcome

Thank you

By BeauDiGi

Expert (72)

BeauDiGi's picture

05-11-2010, 11:52

Looks like a very nice MSX Computer?
Where can I buy this?
What do I see for strange signs on the keyboard?

By BeauDiGi

Expert (72)

BeauDiGi's picture

16-11-2010, 15:45

I want to buy a SANYO WAVY FD2?

Who has one for me?

By BeauDiGi

Expert (72)

BeauDiGi's picture

16-11-2010, 19:23

Or the FD with rensha...

By BeauDiGi

Expert (72)

BeauDiGi's picture

27-12-2010, 18:24

Nobody?

How much of these machine's are there around now a days?

By OeiOeiVogeltje

Paragon (1407)

OeiOeiVogeltje's picture

27-12-2010, 19:59

not many
i think this is one of the rarest machines around

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