#A3000 memory
4 messages in this thread
Searching for help from any A3000 owner out there. Just a few simple questions
<g>. I just fixed up an A3000 16mhz and want to add some memory to it. Don't
have a book though and there are some things driving me crazy trying to figure
out!
1. How are the zip chips oriented? Left or right?
2. I am trying to install 1×4 meg zips. How many do I have to install at a
time, and in what slots?
3. There is a jumper (J852) that is marked 4×256 and 1×4. Does this have
anything to do with the zip slots?
Any and all help will be welcomed.
Thanks
Dege
Pop quiz: Two biggest crooks in modern history? (o\_/o)
Answer: Gould & Ali {-I-}
Dege,
I had to sell my 3000, but I still remember enough to answer your
questions… with a glance at my service manuals. 🙂
1: The Zips 'face front', that is the printed side of the chips face the
front of the machine. Or the beveled corner (pin 1) of the chips face
left.
2: The 3000 is a 32 bit machine, and the zipps are 4 bits wide… so you
need to install 8 chips at a time. The Zipp sockets are organized into 4
banks. You need to install the zips in bank order 0 thru 3. Bank 0 is u850
to U857. It should be silkscreened on the motherboard, but the layout is
not intuitively obvious at first glance. It's basically every 4th chip
fron to back in both rows, starting with the frontmost chip. That's bank
0. Bank 1 goes in behind each of those, and so on. Note that bank 0 is
electrically the same as the DIP sockets just in front of the zipps. (Not
the second meg of chip ram..) If you've got DIPs in there now, you need to
pull them & put them in the chip ram sockets. You can't mix RAM sizes, and
the chips there now are probably 256k x 4. If you were installing 256k x 4
zipps, you could just leave them in and start the zipps in bank 1.
3: The jumper tells the hardware which size zipps are installed, so you do
need to set it correctly.
-Jim
MOS via Autopilot & Amiga
Jim,
Thanx! Clear, concise instructions. Everything the Amiga was and Commodore
wasn't! Added the memory with no hitches. Had to laugh though because
intuitive it ain't! My only concern now is the ram chips I had came from my
386 BB. I don't know if they are static ram are not. Do you have any ideas on
figuring out what they are, or does it matter since they're working? Anyway
thanks again for the quick response and accurate help.
Dege
Pop quiz: Two biggest crooks in modern history? (o\_/o)
Answer: Gould & Ali {-I-}
Dege,
Glad to help. I kinda miss doing that sort of stuff since the store
where I worked died just before CBM. 🙁 Anyway, I figure the layout of
the zipps was for the convenience of the board layout folk, mere mortals
need not apply. After installing the 0'th bank, the rest are easy. As for
the static column ram vs page mode… well it works, that's the main
thing. Either type will work, but the static column mode drams will be
faster. It's not wise (in my experience) to mix them either. You can
sometimes tell from the part number which type you've got. The SC mode
drams have a part number 2 larger than the page mode chips. For example,
Toshiba calls it's SC part the TC514402 and the PM part the TC514400.
Whether or not that's universally true, I couldn't say.
-Jim
MOS via Autopilot & Amiga