Expert, please look at these pics of my 520STfm motherboard.

[+wood_jl]

Well, I got 'er apart today and I am cleaning up the case.

 

So I wanted to see "if I had a 1040ST motherboard" as I have heard some (later??) 520STfm had.

 

But it looks like the previous owner may have had this upgraded to 1MB RAM????? I mean, I thought there would either be 16 "41256" chips and no extra spaces for additional, or I would find 16 more empty space (ala 1040 motherboard). Instead I find this:

 

PICS SHOULD ENLARGE WITH CLICK

 

 

So there are 32 chips on there. Sorry to sound dumb, but this does mean I have 1MB? Yes, it should be obvious but I am not smart with this stuff so I don't want to assume even the easiest thing.

 

Close-up of the RAM shows two different brands. None socketed.

 

 

 

What kind of ROM is "Mega TOS?"

 

 

 

Other than the ROMs, there is only one other chip that is socketed: WHAT IS IT???

 

 

Here is close-up of that socketed chip:

 

 

 

Thank you, thank you, thank you, thank you, and ....THANK YOU!

[+poobah]

Memory: They are all 41256 chips (256K x 1 bit) 32 = 1 MB.

 

ROMs: TOS 1.2 (or 1.02). Same TOS that shipped in the MegaST. Main change is support for the blitter chip.

 

Socketed IC: DMA chip.

[+wood_jl]

Hi, thanks a lot!

 

I take it this "is" a 1040 motherboard, then. However, I don't see any socket (or space for a socket) for a blitter chip. Were those present on the last ones - before the STe came out?

[+poobah]

I'm not sure there were any 'regular' 520s or 1040s that had blitters.

Most of the Megas did, and all the STes

[+Guitarman]

Memory: They are all 41256 chips (256K x 1 bit) 32 = 1 MB.

 

ROMs: TOS 1.2 (or 1.02). Same TOS that shipped in the MegaST. Main change is support for the blitter chip.

 

Socketed IC: DMA chip.

 

Please tell me if I'm mistaken...but...

 

ST is a 16bit system. It would mean that it would used 16 1bit chips to create 256K of ram.

 

2 banks with 16 41256 would make it a standard 520ST with 512K of ram. ....unless the ST accesses memory at 8 bit

Edited April 3, 2010 by Guitarman

[+poobah]

Memory: They are all 41256 chips (256K x 1 bit) 32 = 1 MB.

 

ROMs: TOS 1.2 (or 1.02). Same TOS that shipped in the MegaST. Main change is support for the blitter chip.

 

Socketed IC: DMA chip.

 

Please tell me if I'm mistaken...but...

 

ST is a 16bit system. It would mean that it would used 16 1bit chips to create 256K of ram.

 

2 banks with 16 41256 would make it a standard 520ST with 512K of ram. ....unless the ST accesses memory at 8 bit

 

Regardless of the "bit-ness" of a system, memory capacities are generally specified in bytes (ie: KB-> Kilobyte, MB-> Megabyte, etc.)

 

256K x 32bits = 1 Megabyte regardless of system.

[wongck]

Memory: They are all 41256 chips (256K x 1 bit) 32 = 1 MB.

 

ROMs: TOS 1.2 (or 1.02). Same TOS that shipped in the MegaST. Main change is support for the blitter chip.

 

Socketed IC: DMA chip.

 

Please tell me if I'm mistaken...but...

 

ST is a 16bit system. It would mean that it would used 16 1bit chips to create 256K of ram.

 

2 banks with 16 41256 would make it a standard 520ST with 512K of ram. ....unless the ST accesses memory at 8 bit

 

That's the state of the art at that time.

[AstFan]

...

ST is a 16bit system. It would mean that it would used 16 1bit chips to create 256K of ram.

2 banks with 16 41256 would make it a standard 520ST with 512K of ram. ....unless the ST accesses memory at 8 bit

Data lines from both (usually all) RAM banks are connected together. With bank selection lines (RAS, CAS) select proper bank, of course only 1 at once. So, we have 16-bit RAM. Each bank has 2x256KB, since 16 chips makes twice than 8-bit (byte) ...

[+wood_jl]

English.....english. Some wise charlatan break all this high-tech jive-talkin' down for a real outta town brother.

 

Exactly where are they going with this? Exactly what is "good" or "bad" here, for my dumb ass to either seek or avoid? Just askin'.

[+Stephen Moss]

English.....english. Some wise charlatan break all this high-tech jive-talkin' down for a real outta town brother.

Each memory chip is 256K x 1 this means it has 262144 (256 x 1024) memory locations each capable of storing 1 bit of data, hense each chip stores 262144 bits.

Your total memory will be 262144 x 32 chips = 8388608 bits, we devide that by 8 to get 1048576 bytes = 1Mb. If you could have used Xcontrol or SysInfo to find the memory size and TOS version if you have them.

Looking at the quality of the soldering on the under side of the PBC may reveal if addition memory was added after it left the factory, as Atari made so many revisions to the ST motherboard that it is pot luck which version and therefore memory configuration you have fitted.