beatyr@pur-ee.UUCP (Robert Beaty) (02/25/86)
<<>>
This is just a subtle warning to all of those interested in upgrading
their Atari 520ST's to 1Meg. I attempted to do so two weekends ago and
the result was a non-functional 520ST and about 24 hrs. of wasted time.
Now there will be those out there that will say that I might have
used a wood burning gun instead of a nice soldering iron, but that is not
the case. I am getting my Ph.D in EE and have worked as a tech. for many
a summer. I have performed similiar upgrades to H-19's and Radio Shack
Color Computers ( piggy-backing chips and the like ). This upgrade is
NOT a simple one. It is not due to the fact that the techniques are that
difficult, just that the component values are VERY touchy.
For instance, I tried BOTH the resistor and non-resistor upgrades -
neither worked. I have seen ( since I tried my upgrade ) about the fact
that the values of the resistors are sensitive to the manufacturer of
the 256K DRAM chip. This is not my idea of a good, safe upgrade.
My only warning is this, DO NOT try this if your 520ST is AT ALL as
valuable to you as mine is to me ( doing without it for 2 wks. was very
tough ). If you have the time and the persistance to MAKE it work then
you might want to try it. If possible, find out EXACTLY what combination
of components worked for someone else ( any offers out there? ).
I am not trying to bad-mouth anyone, only trying to save someone like
myself a LOT of grief.
Bobfranco@iuvax.UUCP (02/25/86)
I strongly urge anyone interested in performing the 1MEG upgrade to disregard the previous note. I know of over a dozen Upgrades that worked either right away or soon after (after backtracking and discovering a wiring or some other mistake). The only Upgrade that I know of that resulted in permanent damage is the case of the previous author. I personally found the upgrade to be a relatively simple procedure. Furthermore, I cannot agree that components are all that sensitive - you can heat the DRAMs pretty well before they give out, for example. The one thing the DRAMs are sensitive to is static electricity. If you observe simple precautions against static buildup (aluminum foil on the table and in contact with everything as often as possible) they will not be damaged. Period. Another thing that might cause a problem is powering up a DRAM which is only partially connected (there is a very effective, simple precaution to observe here as well - namely, do not power up until the connections are complete). Also, I have NEVER EVER EVER even attempted an upgrade of any machine before. Also, I have NEVER EVER EVER even looked inside of a computer before. Yet my upgrade has been working for three months now. Notice that I am suggesting that people disregard the previous note and I am not saying whether the author is right or wrong. For all I know the author may be right (but I am pretty sure he his wrong). The reason I am suggesting that the note be disregarded is that absolutely, positively no meaningful information whatsoever was presented to support the conclusion made. I bring this up because this sort of thing seems to happen more than half the time on the net. Please, Please, Please, people. If you are going to make a statement that may strongly affect how others will use their machine, post the deductive path used to come to the conclusions you make!!! Remember, you are not talking to your friend down the block - you are talking to perhaps tens of thousands of people. Be responsible! Please.
jan@looking.UUCP (Jan Gray) (02/26/86)
In article <3806@pur-ee.UUCP> beatyr@pur-ee.UUCP (Robert Beaty) writes: > This is just a subtle warning to all of those interested in upgrading >their Atari 520ST's to 1Meg. I attempted to do so two weekends ago and >the result was a non-functional 520ST and about 24 hrs. of wasted time. > . . . > If possible, find out EXACTLY what combination >of components worked for someone else ( any offers out there? ). I upgraded my ST months ago and it worked first time. I used NEC 41256-15 DRAMs (*exactly* the same part as my Atari installed DRAMs, but manufactured five weeks later!) I did not install resistors, and I'm not sure if I will. I do not have the ROM upgrade yet. One poster to the net said installing ROMs fried his resistor-less upgrade, but others said it worked fine without resistors. If the damn resistors are so important, why didn't Atari install them on the lower 512K bank? Jan Gray Looking Glass Software, Waterloo, Ont. (519) 884-7473
luscher@nicmad.UUCP (03/02/86)
I have updated 3 machines to 1 meg, using TI and Mitsubishi drams. On one of the machines one of the drams didn't work (anti-static foil was used so I must assume the chip was bad from the factory). This machine still booted (with 1/2 meg.) since the boot found bad memory in the top 1/2 meg. As a developer, (i.e. SID debugger and schematics) I found it relatively straightforward to find and fix the problem, although time consuming. All of these used the (unnecessary?) 68 ohm resistors. It is up to the individual to assess their level of expertise in a mod like this, and/or their willingness to gamble on the outcome and the possible steps they may have to take if things go bad. My experience has been positive on the whole. -- Jim Luscher / Nicolet Instruments / Oscilloscope Div. 5225 Verona Rd Bldg-2 / Madison Wi 53711 USA / 608/271-3333x2274