About NeoGeo memory chips

dr.wily

dr.wily

n00b
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May 24, 2005
Posts
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Simple question : how many memory NeoGeo have ?

In fact, tech doc on the internet say 64Kb of work ram and 68Kb of vidéo RAM and 2Kb for z80. OK, it seem logic when I look at the NeoGeo motherboard.

But when you look closely there is another memory chip who do not enter in general specification. Some pic :

- Motherboard with SRAM chips
- work ram (64ko)
- Video ram (64ko) (where is missing 4Kb ?)
- Z80 2Kb ram

and unknow sram chip :

- Unknow 16 Kb sram
- Unknow 32Kb sram

What is the use of these chips ? Any idea ?
 
Last edited:
channelmaniac

channelmaniac

Mr Neo Fix-it
15 Year Member
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Nov 29, 2005
Posts
4,316
There are three sets of the 256kbit chips on the board...

Set 1: backup ram
Set 2: work ram
Set 3: video ram

The cxk5814 chips are the fast video ram

The cxk5864 chips are the pallette ram

The 6116 chip is the sound ram

Although a search of the forums would've gathered you the answers.
 
dr.wily

dr.wily

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May 24, 2005
Posts
31
Ok, thank. But all documentations on the Internet are wrong ?

What is the real total amount of RAM in Neogeo ?

Can you tell me what ram chip is for ?

You say :
5814 chips is for fast vidéo RAM. (how many Kbytes ?)
5864 chips is for palette RAM. (how many Kbytes ?)

But these chips

cxk5825 (x2 bottom left near 68k & ym) : work ram or video ram ? how many Kbytes ?

cxk5825 (x2 upper right near lcpc) : work ram or video ram ? how many Kbytes ?

Thank for your useful information !
 
dr.wily

dr.wily

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Posts
31
Many thank guys !

My last question,

how many kByte for 5814 chips for fast video RAM ?

how many kByte for 5864 chips for palette RAM ?

Datasheet about these memory chips is not clear on this subject.
 
channelmaniac

channelmaniac

Mr Neo Fix-it
15 Year Member
Joined
Nov 29, 2005
Posts
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JEEZ yer lazy...

Google is your friend....

5814 is 16kbit

5864 is 64kbit

Divide that by 8 to find how many kbytes.
 
dr.wily

dr.wily

n00b
Joined
May 24, 2005
Posts
31
I know that I must divide by 8 to find the value in kbyte (all neogeo users knows that !). But I did not know the value in Kbit. In datasheet this value is not explicitly write.

But thank for reply me ;)

If I ask for memory it's because my Neogeo give a red screen and refuse to boot game, only red screen. I search someone who can fix this. Yous can ?
 
Last edited:
FalcomAdol

FalcomAdol

Fio's Quartermaster
Joined
Feb 24, 2007
Posts
499
Try to boot the MVS with no game cartridge.

Does the MVS also give you a red screen, or do you get the test screen?
 
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