Modify EXM-002 memory board?

you can get the full resolution bitmaps from the files section in the akai S1000 / S1100 yahoo group. they are part of the collection of schematics for the S1100 (schematics7 and schematics8)

this just got a lot easier!

this is for the exm005 with dip chips and the exm008 with sip chips. the smd versions should be identical to the electrical schematics though.

This is a great find. Thanks for posting this, getting very interesting now.

I think that both schematics should be imported and uploaded to osh regardless.

Even the SCSI board schematics are listed. This is quite useful man.

@star one - i know you cannot upload schematic files, lol. But since those memory boards are 2 layers I'm sure you'll have a quick time importing them into eagle.

I must say, locally I have access to several surplus stores so getting different memory types for testing won't be an issue. (Save a lot of time waiting for stuff to come in from Asia for sure).

Just looking online and I've seen 5 different design versions of the 8mb boards, not including Mutec or the Akai ones.

It's interesting to see the different board layouts people have thrown together.

Can you guys find an alternative to HM514100ZP10? If I just do 20pins and run them according to the schematic, we would have to get super lucky to find the right configuration on whatever ram ends up being used.


Specifications

Generic Number :
Military/High-Rel : N
Tech. : CMOS
Number of Words : 4M
Bits Per Word : 1
t(acc) Max. (S) : 100n
tW Min (S) : 180n
Output Config : 3-State
P(D) Max. (W) : 1.0
Nom. Supp (V) : 5.0
Minimum Operating Temp (шC) : 0
Maximum Operating Temp (шC) : 70
Package Style : ZIP
Mounting Style : T
# Pins : 20
Description : Page Mode Cycle 55ns min.


Read more: http://www.americanmicrosemi.com/information/spec/?ss_pn=HM514100ZP10#ixzz3Wfoueca7


If I run it like this on the board, to those pin numbers, and say we use something else where 5 is VCC and and pin 3 is Data, that wouldn't work out so well haha





I got this far as of now




The IC's here I used the CD74ACT541M the pins are in the correct positions to the CD74AC541E. Everything is just drawn up funny, but the 541E will drop in and match to the original.

There are compatible alternatives to the HM514100 series, it's really dependent on whether you want to you a zip package or not.

I'll look more into alternatives. Thing is, while this is a cool project and all, but at the moment sourcing the necessary/compatible dram/cmost memory isn't as cost effective as I'd like.

search zip DRAM on ebay, theres a ton.

the 16 ram chips in the exm008 are 4m x 1 bit chips. nobody makes these any more.

its possible to make a board that uses just four 4M x4 bit chips.

still it'd still be better to make a memory card with two simm sockets.

richie wrote:There are compatible alternatives to the HM514100 series, it's really dependent on whether you want to you a zip package or not.

I'll look more into alternatives. Thing is, while this is a cool project and all, but at the moment sourcing the necessary/compatible dram/cmost memory isn't as cost effective as I'd like.

Looking for something that will work, won't cost anything but time

I'de gladly trade looking for chips then doing this board LOL! Plus it'd be a major waste of time to design it around something that doesn't exist, so the end result will never work


It's no rush on anything really.

motosega wrote:still it'd still be better to make a memory card with two simm sockets.

Completely agree. I just wouldn't know how any of that stuff works.

@motosega I obviously know there are a ton of them on eBay -- for ridiculous prices.

i had my s1000 open today, replacing the backlight. 20€ from ebay, peice of cake to install.

so i measured the ram card:


https://imgur.com/jQCBXgn


StarOne: replacing the chips with a simm isn't really that crazy, the signals on a simm corespond to the signals on the schematic. you just need to match them up.

if you look at the schematic of a 30pin simm you will see that its pretty much identical to the Akai board. read the wikipedia page on dram chips and you should be ready.

did you find a source for the connector?

shame this didn't go any further. maybe one day i'll have a free week and a sudden attack of inspiration. stranger things have happened

all the info exists, one day it will happen. this has not been in vain, thanks for the research guys!

since the chip prices are too high to remake the original boards there are only two realistic ways to go:

1. use a bigger ram chip with more address/data lines to replace all the chips.

2. put a simm sockets on the board.

Like I kept saying, if I knew enough to do the stuff as SIMM's, I would have

Be easy enough to pick back up on. Even someone browsing this might want to check it out with all thats listed here. Or hell one of us.