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RAM chips


CPUWIZ

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I am curious if anyone would be interested in posting pictures or manufacturer and chip data, of different RAM chips found on 7800 motherboards?  And if they are socketed (if no pic available).

 

Could be valuable info, for any hardware designer, that survives the moroncalypse. :)

 

Random fresh one, I pulled (no socket mobo, got it bare)...

 

2021-02-15.jpg.cb3e87fd6cc30b77176188cd40ace6fb.jpg

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Had I know there was interest in this, I could have been doing this all along with all the 7800s I've found. Let me go through my pics from client service work and see if I have any that show the ram up close enough to share. I've seen many different brands and I know they are different speeds as well. I've often wondered if the ram speed differences in the variants is part of the hardware issues we find, especially with the extra timing circuit since I can literally see a game work or not work simply touching that cap into circuit without resetting or power cycling the console?

 

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Okay... I just went through the pics I was able to make the manufacture and chip PN from and here are the ones that are unique that I was able to find in my records. The odd thing is the Sony chips apparently have at least 3 different speeds being used and as a result a different resistor attached as well with one of them having a 370Ω and most having a 100Ω.

 

Most of the ones in sockets were earlier '84 revision boards. Also these are different sizes as the original pics I cropped these from are different sizes or taken from different distances to respect of the original pic I cropped them from.

 

I think the pics are enough to show which were in sockets and which were not, also I would say I usually see them more often with resistors tide off ground to the write enable pin on the bottom chip. On those that have the resistor bodged in, the trace to that pin on the bottom has been severed at the factory.

 

Goldstar - Seen these on mostly newer revisions.

Goldstar_GM76C28-10.jpg

 

 

Hitachi in an older '84 revision board. 

Hitachi_HM6116-3.jpg

 

Another Hitachi in an older '84 revision board but different speed.

HM6116-2.jpg

 

Samsung. Soldered in with a 100Ω? resistor

KM6816AL-15.jpg

 

Motorola, I don't believe this was actually socketed originally and was one I replaced thinking it might be bad. No resistor

Motorola_MCM61L16P15.jpg

 

Motorola in sockets with a resistor

Motorola_MCM6116P15.jpg

 

NEC - I don't see many with this brand of RAM on them but they are out there. No resistor

NEC_D4016C-5.jpg

 

OKI - Seen a few of these on middle '87 units usually. No resistor on this one and soldered in.

OKI_M2128-15.jpg

 

OKI again that is soldered in but with a 100Ω? resistor I believe.

OKI_M2128-15_wR.jpg

 

RCA - I've seen these mostly on older (Possibly original '84) units. Socketed

RCAX_CDM6116AE3.jpg

RCA socketed again but this one didn't have the resistor on it.

 

RCAX_CDM6116AE3_NoR.jpg

 

Sony -10L with the 370Ω resistor. Soldered in.

Sony_CXK5816PN-10L_w370Ω.jpg

 

Sony -12L with a 100Ω resistor and soldered in.

Sony_CXK5816PN-12L_wR.jpg

 

Sony -15L with no resistor and soldered in.

Sony_CXK5816PN-15L_NoR.jpg

 

UMC - soldered in with no resistor.

UM6116-2.jpg

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Wow, thanks Jesse.  Sick variety of speeds.

 

2

3

5

10

12

15

 

WTF?

 

FYI, the resistor is connected to the write enable line.  Why only on one is a bit weird, maybe they had a collision of some kind and put a pullup on one.  It probably doesn't matter which one it is on.

 

page2.png

 

 

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Yes I mentioned that the resistor was attached to the WE pin on the chips. I thought the different values seem to correlate with the speeds so faster chips like the Sony 100ns has that 370Ω on it whereas the 120s only have the 100Ω on then many of the 150 - 200 do not have it.

 

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3 hours ago, Mitch said:

Have you seen the RAM daughter-board that is on a lot of the PAL 7800s? I thought I had a picture but can't seem to find it at the moment.

 

Mitch

 

No, I know nothing about the PAL machines.  Love to see it though.

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12 hours ago, Mitch said:

Have you seen the RAM daughter-board that is on a lot of the PAL 7800s? I thought I had a picture but can't seem to find it at the moment.

 

Mitch

I have this version, but I'm not at home right now, so I'm pasting photos borrowed from the internet: 

 

WP_20160917_004-720x540.thumb.jpg.c96436eae12d5ed53ddfa9b90e0dc94d.jpg 

WP_20160917_006.thumb.jpg.c883f9e7e643d249e8fe8daf945cf40b.jpg

 WP_20160917_007-320x240.jpg.27c070065fb4b5861d12e349ad63115e.jpg

 

 

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The pictures that RJ posted are what I was thinking of. I pulled my PAL 7800s apart and they both have the same RAM chip model just different date codes. The one with the riser board must be one of the 7800s I had on loan to Curt. Not sure if I will ever see those again or not.

 

Mitch

PAL7800RAM.jpg

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1 hour ago, Lynxpro said:

On the subject of the riser card, did the French models have a riser board for SCART? Maybe I'm confusing what I've seen before in pics elsewhere with these RAM risers. Odd.

Yes, there was a riser board that replaced the RF modulator. It had an Atari ST 13 pin monitor port on it. That model 7800 shipped with an ST to SCART RGB cable though.

 

Mitch

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16 hours ago, Mitch said:

Yes, there was a riser board that replaced the RF modulator. It had an Atari ST 13 pin monitor port on it. That model 7800 shipped with an ST to SCART RGB cable though.

 

Mitch

 

But it wasn't really analog RGB output, was it? My understanding was that it was whatever SCART's version of Composite was.

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