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simon_the_s
June 6th, 2012, 02:26 AM
Hi

Im new to this forum but i hope someone can help me.
I rediscovered my old olivetti m24 stashed away and decided to try to get it running - i think it has been about 15 years...

When i boot it, it seems that it stops during the ram count.

9212

http://imageshack.us/photo/my-images/716/img1081xr.jpg/

if i remember correctly there should be 640kb ram - but for some reason it stalls.

I dont rly have any idea what to do - so i opened her up.

but where on earth is the ram even located?

9213

http://imageshack.us/photo/my-images/256/img1083dt.jpg/

oh well - if anybody knows anything that could help - please let me knwow - i would like to get it up and running.

regards

simon

ChrisCwmbran
June 6th, 2012, 03:52 AM
9215

The RAM is the area marked in red on this copy of your image. I would carefully remove and reseat these chips and try it again.

simon_the_s
June 6th, 2012, 05:21 AM
thank you - but arent half of those within the circle soldered to the board?

im not at the computer atm - but i will see to it and come back.

ChrisCwmbran
June 6th, 2012, 05:25 AM
I would think you will find that the 192Kb it counts successfully is probably the soldered RAM, with the expansion to 640Kb being the socketed RAM.

Chuck(G)
June 6th, 2012, 07:47 AM
It varies between versions of the motherboard. The service manual may be of some help--it's on bitsavers under the "ATT" pdf directory. On mine, the soldered-in RAM is the base 512KB; 256Kb chips. Others populate the same area with 64Kb chips and the expansion area with 256Kb chips.

simon_the_s
June 6th, 2012, 11:05 PM
thanks alot for the manual hint - it still bothers me that the system doesnt start even with only 128kb - it should be able to...

chuck do u agree i should try removing the socketed ram - i really dont want to mess this up more :)

Chuck(G)
June 7th, 2012, 07:38 AM
The socketed RAM shouldn't hurt a thing if removed.

FWIW, I discovered that I have the BOS 1.43 update documentation--not only did it come with new PROMs, but also with a new memory mapping PAL.

simon_the_s
June 18th, 2012, 10:41 PM
I tried to resocket the ram - did not help at all - and i rly stabbed myself under one of my nails removing one of them :(

RWallmow
June 18th, 2012, 11:09 PM
I tried to resocket the ram - did not help at all - and i rly stabbed myself under one of my nails removing one of them :(

Unfortunately you may very well be looking at a bad soldered ram chip. I recently ran into this in my Apple IIe, I desoldered the chip, soldered in some SIP socket and made it removable (http://wallmow.com/photos/index.php/Vintage-Computers/Apple-IIe-Printed-as-e/DSCN0792). You may also be able to test by piggybacking a known good (equivalent) ram chip on top of the others to help locate the bad one.

simon_the_s
June 18th, 2012, 11:38 PM
im not sure what u mean by piggybacking - but im guessing changing the blocks one at the time with one i know works - unfortunately i dont have an extra block - and during the resocketing i tried starting the computer without all the blocks - but without all the blocks the computer was unable to startup - or rather it did seem to power up - but nothing displayed on the screen - i tried with only top row socketed and then only bottom row - but same result

RWallmow
June 19th, 2012, 05:10 AM
im not sure what u mean by piggybacking - but im guessing changing the blocks one at the time with one i know works - unfortunately i dont have an extra block - and during the resocketing i tried starting the computer without all the blocks - but without all the blocks the computer was unable to startup - or rather it did seem to power up - but nothing displayed on the screen - i tried with only top row socketed and then only bottom row - but same result
Piggybacking (see figure 3) (http://www.classic-computers.org.nz/blog/2010-08-29-restoring-an-atari800XL.htm) is putting a known good one over the top of the existing soldered ones so that the legs of it make contact with the legs of the existing ones. You might be able to get away with pulling one of the last chips from the last bank to piggyback, assuming all the chips are the same size, but if that's supposed to be 640k in those 4 banks, I am not sure if they all would be the same size, you would need to research all the part numbers. Or post the different part numbers here, I am sure one of us could tell you if they are all equivalent parts.

Thanks to fellow VCF member Tezza for his great page with photos on piggyback testing his Atari 800XL!!

EDIT: I see now you tried booting with a bank removed and it was a no-go, you probably have to jumper something or software configure it (which I realize is not possible, since it wont fully boot) to disable that bank before you remove it. What are the part numbers on your RAM chips, one of us might have a comparable one we could sell/ship you for cheap for testing. Your profile doesn't say where you are located, but their are members in almost every country who probably have something in their stock pile they could sell/trade you for a good price for testing & repairing your system.

Compgeke
June 19th, 2012, 06:13 AM
Here's a copy of the service manual (http://compgeke.com/files/PC6300/PC6300ServiceManual.pdf), do a search for 3-12 for the ram jumper settings, it'll be the last result. Scroll down a little bit (page 3-16) for the dip switch settings for ram amounts.

Trixter
June 21st, 2012, 11:43 AM
Also, don't give up -- if it really is a RAM problem, which it sure seems like it is, it is one of the easiest problems to fix or workaround (piggybacking).

RWallmow
June 21st, 2012, 12:18 PM
Also, don't give up -- if it really is a RAM problem, which it sure seems like it is, it is one of the easiest problems to fix or workaround (piggybacking).
Exactly, it can be a semi-permanent fix if you leave the piggybacked chip in place if you are not comfortable soldering. However ultimately I think most here would recommend soldering in a socket and replacing the chip, you might even be able to get someone more comfortable with soldering to do it for you for little money.

What part of the world are you in? Maybe someone on this forum who is willing to solder-for-cash (or parts, lol) lives nearby to you.