paulz@olnl1.UUCP (Paul v.d. Zwan) (03/28/90)
Has anyone ever tried upgrading a Mega 2 ( late 1987) to 4 MB. ?
It has room for 10 more RAM chips on the motherboard. Is an upgrade
as easy as I hope it is or is there catch to it. ??
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# Paul van der Zwan # {mcvax,uunet,hp4nl}!olnl1!paulz
# Olivetti Nederland B.V. #
# Marketing Support (Xenix,Unix,X/OS) #rich@lakesys.lakesys.com (Richard Dankert) (04/08/90)
In article <9552@sdcc6.ucsd.edu> pa1562@sdcc13.ucsd.edu (C. SQuibby Breyman) writes: >I tried bumping my 520stfm up to 1meg the same way. Solder wick >sockets and caps. I socketed and capped. Runs ok. Added DRAM, boots >gets verticle lines and bombs. Serious bombs. So badly that it >didn't even display them. Tried reboot. No luck. Added some resit >ors to the resitor slotss next to the ram. Comes up ok but only >recognizes the lower half of memory. Stuff Deleted.... I went through this a little while ago, with TWO STfm's I have at my workplace and here's what has to be done.... Follow the New Bank of Ram down towards the front of the machine. You `should find a chip just off to the right on the way down, U68 and it should be a 74LS11N chip. If it is missing, your going to have to get one, and place it in there. The Hitachi # is HD74LS11p There are three resistors that are not soldered in also, I believe there the ones that you have made referece to. #'s R71 / R72 / & R73, and should be 33 Ohms @ 2% tolerance. You machine should boot, and recognize the second bank. The pad that you are referencing to are for two or six set ROM's! There are three of them, two by the Rom chips and one by the MMU (MCU) chip. There labeled 256K and 1M (or 1 Meg). If you are not replacing your ROM's then LEAVE THEM ALONE! There is a place on the mother board to install a Blitter Socket and CHIP, But seeing that I use TurboST, and I have seen blitter installed machines, and due to the type of use i am using the machines for, I have no need for the blitter, so I have not investigated installing this. Fact is that besides the blitter, there was (on both machines) another chip that more than likely has to be installed if you desire the blitter upgrade in. Like I said, I don't have the need, so I just never went any farther, #include <std. disclaimer> I have doen the upgrade to both machines, and all is well. I am a Tech, and was working on MY OWN MACHINES! If you try this and your machine blows up in your face, I take NO respopnsibility. rich..... UUCP: rich@lakesys.lakesys.COM {always .... }