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View Full Version : Found HM4816 RAM Chips for Acorn BBC



TheCorfiot
30th August 2011, 12:44
Hello my friends...

Looking to refurb an Acorn BBC Micro Model B for our resident Wizard.

I need to source some RAM chips of the 4816AP-3 variety

and some 74LS245N IC's too.

If anyone can help in any way it would be much appreciated

Regards
TC :thumbsup:

Zetr0
30th August 2011, 13:24
@TC

my friend, I may have some LS245's and I have a slew of 16pin DIP KM4164B-10 (64k*1) memories.

I couldn't find any spec sheet for the 4816AP-3 =(

anyway the above are yours if you can make use of 'em =)

LTAC
30th August 2011, 13:54
Datasheet HITACHI HM4816 (http://dl.free.fr/kAZxDAA4z)

Zetr0
30th August 2011, 14:11
Datasheet HITACHI HM4816 (http://dl.free.fr/kAZxDAA4z) :thumbsup::thumbsup:


@TC

My friend, these 4164's look like drop in replacments... they look pin conpatible!

http://s2.postimage.org/4rrboce9y/lookie.jpg (http://www.postimage.org/)

just let me know how many you want =)

TheCorfiot
30th August 2011, 23:58
Hmm Now that's interesting, thanks for that Zeets :thumbsup:

I've got a couple of 4164's here from when I upgraded my TRS-80 CoCoII to 64K (swapped them for 4464's)

I will give it a go by holding the A7 pin down to gnd & see if they can cope with the 4MHz DRAM refresh clock that the Beeb uses.

If it works I could certainly do with a dozen or so as I have another board here with a RAM fault (fatbob_gb) I just haven't been able to get hold of the HM4816's easily to fix it..
Refurbing this one for you has given me the push to get them both going..

Interesting & Cheers Chap

TC ;)

Zetr0
31st August 2011, 00:53
Thats awsome buddy!

I have 36 of them... infact I am not sure how I got them.... freaky... anyway I am still waiting on some bits for your parcel so I shall send half of what I have out to you if there any good =)

the ones I have here are the -10 (100ns) varients... which are pretty damn quick for most applications... should be able to cope with a 4MHz bus =)

TheCorfiot
31st August 2011, 09:20
Cheers Zeets

I've posted over at Stairway to Hell forums to see what the techy guys over there make of it too..

http://stardot.org.uk/forums/viewtopic.php?f=3&t=4428&sid=21158d571d50c8a5b7c3af0cd9d8b7e6

The guy's over there are very knowledgeable too will be nice to see what they have to say

Cheers again
TC :thumbsup:

TheCorfiot
31st August 2011, 19:49
Zeets

The 4164's I have are 18Pin not 16Pin

Everywhere I look at datasheets I find 16Pin versions of the 4164, god knows what mine actually are, as I mentioned earlier these were taken from my CoCo & they are marked 4164 ????. The 4464 is also 18Pin which is what i used to replace the originals with.

Wierd :lol:

On a lighter note I have traced the fault on one of the boards to a single DRAM in the CAS1 bank, quick desolder, fitting a socket & borrowing a DRAM from one of my working Model B's proved I was correct.
So if I can get hold of a replacement DRAM that's another Model B Beeb fully repaired & back in the land of the living.

TC :whistle:

Zetr0
31st August 2011, 20:40
@TC

my friend, the ones i have here are 16pin (DIP )

I have just counted them three times LOL... there certainly 16pin like the schematics above that I got online... one from LTAC's link the other from all DataSheets...

I am sure there might be a specific 18PIN dip varient... but these little puppies are indeed 16pin KM4164B-10

I think I got this cache I have here from fleabay, problem is I cannot remember what they were listed as... If memory serves (forgive the pun) these were from a joblot a few years back that was into 8bit computer repairs... I got a bunch of 27c32's 64's and 128's aswell as some new resistors / caps and some common TTL IC's....

Thinking about it.... I may of got these before AmiBay was aroud..... t'is'was a while back my friend..... =)

Anyway I got the following in a box

36x KM4164B-10 (64k * 1 bit ) - 16 PIN DIP (Samsung)
18x M5M4256-AP (256k * 1 bit ) - 16 PIN DIP (Mitsubishi)
15x M514256A -70 (256k * 4bit ) - 20 PIN DIP (OKI)

now the OKI's are spoken for... but your welcome to half the others for grattis =D

TheCorfiot
31st August 2011, 20:46
Cheers Mate

If I can take 16 of the KM4164B-10 (64k * 1 bit ) - 16 PIN DIP (Samsung)
off your hands that would be great.
I may have to replace all the DRAMS in the bank to the same type if it works hence the qty required ;)

Having checked the Beeb's PCB Pin 9 (A7) is not connected to anything either.

Thanks indeedy

TC :thumbsup:

Zetr0
31st August 2011, 21:01
my pleasure my friend.... instead of waiting for the parcel I am sending these will go in a jiffy bag tonight =)

hit me up with your deets please =D

TheCorfiot
13th September 2011, 00:20
Just to update the thread

The KM4164B-10 DRAMS that Zeets sent function perfectly and are straight drop in replacements.

I replaced just the defective DRAM & the KM4164 seemed quite happy sharing the Bus with the HM4816's

Sorted :thumbsup:

Zetr0
13th September 2011, 01:29
Just to update the thread

The KM4164B-10 DRAMS that Zeets sent function perfectly and are straight drop in replacements.

I replaced just the defective DRAM & the KM4164 seemed quite happy sharing the Bus with the HM4816's

Sorted :thumbsup:


AWESOME! :thumbsup::thumbsup::thumbsup::thumbsup:

rkauer
13th September 2011, 01:42
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