Upgrading 520STF C070789-001 Rev F2 to 1Mb - which components?

[joedredd]

Hi,

 

I've bought an Atari 520STF which had a dodgy floppy drive and I've fixed replacing some caps following a thread on this forum.

 

Now I can load the many games that came with it, I notice many of them require 1Mb so it's time to upgrade. I'm not interested in going larger than that and would like to keep the machine original(ish).

 

I'm after advice on what else I need to buy as I'm really very rusty on my electronics.

I opened it up and found the attached photos.

 

Looks simple enough, digging around I decided to order 16 x 256kbit chips TMM41256AP-12 which are Toshiba DRAM of the same spec that's on the board already.

 

Rather than solder direct to the board I'm going to order these IC Sockets from Farnell which should be OK rather than soldering direct to the board for obvious reasons.

 

I understand that those brown capcitors are Decoupling Capacitors of 100nf / 0.1uF ? I've no idea what these are - any pointers?

Any idea if I also need three 68 Ohm resistors for CAS and RAS signals - R71, R72, R73 (so I've read!)

 

If someone could kindly point me to the relative component on Farnell I'd really really appreciate it, many thanks.

[Lynxman]

Capacitors: 220nF / 0.22µF

Sockets, DRAM and Resistors: correct

Edited September 20, 2013 by Lynxman

[joedredd]

Capacitors: 220nF / 0.22µF

Sockets, DRAM and Resistors: correct

 

Thanks. So are these just normal caps I need then, not these "Decoupling Capacitors" ?

 

Also I note the resistors are aligned alternately, I assume I carry on the same trend?

Edited September 20, 2013 by joedredd

[ParanoidLittleMan]

Capacitors must be ceramic type. 'Normal' caps will not filter well. Usually, ceramic capacitors are called decoupling cap.

And I think that better would be to go on 2.5 MB - with 16 x 1Mb chips. Not more work (except 1 line +) and chips should cost not much more.

[Lynxman]

I agree to the capacitors.

But i do not agree to "not more work"

The pinout from 1Mb chips is different. The 256k chips have 16 pins, the 1Mb have 18 pins.

 

Very easy to use the 256k chips.

[joedredd]

Thanks, I already have the chips, really don't have any intention to use this machine beyond a few games.