DRAMs for V9990 VDP ?

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Por lezanderson

Resident (36)

imagem de lezanderson

20-01-2015, 13:44

Hi.

Does anyone know which DRAMs are compatible with the V9990 .. ideally with full part numbers so I can check if they are still available. Also What ROM is compatible with the V9990 ??

** Plus

Which RAM/RAM goes with the YMF278B OPL4 PSG ??

Thanks

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Por l_oliveira

Hero (534)

imagem de l_oliveira

02-02-2015, 21:58

V9990 uses "DUAL PORTED" DRAM. It's a special kind of DRAM. You can use 64Kbit (per bit) or 256kbit memories.
For example the 64Kbit memory is what Mega Drive uses. uPD42264 is one of the kinds it can use.
http://www.alldatasheet.com/datasheet-pdf/pdf/145412/NEC/UPD...

Now if you plan on making a GFX9000 with the V9990 chip you MUST use two 8 bit banks of 256Kbits memories.

On my GFX9000 clone I use four uPD42274 chips (ZIP package) which totals for 512KB.
http://www.alldatasheet.com/datasheet-pdf/pdf/145416/NEC/UPD...

Technobytes used 2xSamsung KM428C256 (8bits) DRAMs on their GFX9000 clone.
http://www.alldatasheet.com/datasheet-pdf/pdf/129863/SAMSUNG...

These RAMs are special for video processors, they have a secondary serial port which is used for the raster display rendering. That allows for accessing the RAM from CPU side even while the video is in middle of drawing.

For the Moonsound you can use any 5v 8bit SRAM. A strong candidate is Hitachi HM628512, which is what people put on their original moonsound cartridges...

Por tvalenca

Paladin (747)

imagem de tvalenca

05-02-2015, 16:29

Lezanderson, are you going to sell V9990 and YMF278B kits? Cool

Por lezanderson

Resident (36)

imagem de lezanderson

06-02-2015, 10:59

No... There's no demand for surface mount stuff..

However You can get a quote for the ICs direct..

Just simply email part numbers quantities direct to info@funkward.com

then ask for Best price or give your Target price and negotiate any discount... pay by PAYPAL and items arrive in about 10 working days from China. Test chips as soon as they arrive, if possible .

http://funkward-tech.ecrater.com/
http://stores.ebay.com/P-A-Electro-Components

Hope this helps..

** look at ebay.com to get a guide on prices, then you can get a discount on that price !

Por lezanderson

Resident (36)

imagem de lezanderson

09-02-2015, 14:14

got quote for V9990s + DRAMs

V9990 can be sourced for about $20 each
upd72274v-10 zip $3.5/ea new
km428c256j soj $3.5/ea used

B/Rgds,
Paul

Funkward Technology Co.,Ltd

Por l_oliveira

Hero (534)

imagem de l_oliveira

09-02-2015, 16:56

So you will pay $14 for the four ZIP NEC DRAMs (you need four as they're 4 bit parts) and $7 for two of the SAMSUNG DRAMs. But the SAMSUNG DRAMs are pulls from scrap (which could be broken).

Tricky choice.

Por lezanderson

Resident (36)

imagem de lezanderson

09-02-2015, 17:50

I'd tend to go with NEW stuff as the SOJ must of been de-soldered ??

They will refund or send replacement if stuff is found DUFF..!

You'd probably get a V9990+ upd42274 DRAMs (4pcs) should be about $35

Note upd42274 NOT upd72274 !

I'd email them and ask for Best Price saying your all-in target price is $35... ??

Might be worth shopping around for Best Price

Ones to Try .. at ebay.com

POLIDA

G&C

etc etc

Por l_oliveira

Hero (534)

imagem de l_oliveira

09-02-2015, 18:39

I know the uPD42274 ones I used on my self built V9990 board came from a IBM MCA XGA-2 card:

So I still have enough to make another.

Here's how the board looks like:

Pretty hand-made design, one of a kind. Both the V9990 and YMF278B boards work a charm.

Por lezanderson

Resident (36)

imagem de lezanderson

12-02-2015, 10:51

Hi.

Do you have the schematics etc... are you planning on making a PCB ??

Por lezanderson

Resident (36)

imagem de lezanderson

17-08-2015, 14:53

l_oliveira wrote:

So you will pay $14 for the four ZIP NEC DRAMs (you need four as they're 4 bit parts) and $7 for two of the SAMSUNG DRAMs. But the SAMSUNG DRAMs are pulls from scrap (which could be broken).

Tricky choice.

They will replace /refund if any ICs are DUFF... obviously you have to test them as soon as they arrive.

Por Dirty Harry

Resident (45)

imagem de Dirty Harry

17-08-2015, 15:02

V9990 + DRAMs can be found on ebay...

V9990 are about $20 each
http://www.ebay.com/itm/V9990-YAMAHA-V9990-VDP-IC-MSX-/40076...

km428c256j soj
http://www.ebay.com/itm/RAM-KM428C256TR-6-SAMSUNG-SOJ-Packag...

Has anyone bought any of these.. are they OK ??

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