Adding ram chips to A500 mobo

[Spaffy]

Hi all. I have recently aquired a lovely Ra5-2mb for my A500 thus leaving me with a spare 512k expansion board. I would like to remove the ram and install it on my motherboard giving me 1mb chipram but the mobo ram is 80ns and the expansion ram is 10ns. Obviously im going to remove the resistors and install these too but will the differing speeds cause problems ?
Thanks in advance stu

 

[roy_bates]

is that a typo 10ns? do you mean 100ns or 70ns.



if its 100ns then no probably, if its 70ns then yes.

 

[Spaffy]

I may be wrong but doesnt the last number on the chip refer to its speed ?
The ones on the board have 80 at the end and the ones on the expansion have 10 at the end

 

[roy_bates]

as far as i know 10ns is pretty damn fast

i suspect it means 100ns ram,i could be wrong though untill someone comes along and says different

 

[TheCorfiot]

10 = 100
12 = 120
15 = 150
6 = 60
7 = 70....... etc.

Most manufacturers leave off the last zero

TC

 

[Spaffy]

So the 80 is actualy 800 ? Wow thats super slow !
Will there be an issue if i add the 100s to the board ?

 

[TheCorfiot]

Spaffy, some manufacturers ignore the last zero, not all, the 80's are 80's

100's should work fine if they were already fitted to the chipram expansion card..

TC

 

[rkauer]

^ What Bas said.

100ns may be a tad slow, but I think you'll not run into problems. Just do the 1Mb hack on the mobo, check if it works alongside with the RA5 and only then add the socketed chips.

Don't forget the companion decoupling capacitors on the near edge of the board! 100nF ( 0.1μF) is the correct value for those little pesky capacitors.

 

[ChrisUnionNJ]

I thought when you add ram to the empty banks on a 500 the speed
has to match the ram thats already there or the system will not
be stable..

 

[rkauer]

No need to match on the A500, mate. On A3000 speed does matter.

 

[Spaffy]

Well i think i shal air on the side of caution and remove the sockets from the expansion aswel and mount those first to make the cips interchangeable.
Hmmmmm brainwave alert...... Get another expansion and socket the whole ram section

 

[TroelsDK]

Remember to carefully photograph every little step and post it here

 

[rkauer]

Remember to carefully photograph every little step and post it here

Aka "hardware pr0n". We like it!:nod:

 

[cpiace64]

you can add chip ram, but first verify release board and version of big agnus

 

[Nikodem]

Which revision of the motherboard do you have?

I have rev.6a and added the memory on the motherboard, it works but it makes the trapdoor slot unusable. I've heard that there is a way of using both - 1MB chipRAM onboard and 0,5MB fastRAM in trapdoor expansion.

 

[Spaffy]

My board is the 6a revision and i have the newer agnes chip.
Im putting the chips on to the mobo and not doing the hack to disable the trapdoor. If i did that then it would defeat the object of the 2mb expansion.

 

[cpiace64]

i have 6a and same expansion, add chip ram and test in the next week

 

[Spaffy]

All this fuss for an extra 512k lol
Thats what makes amiga so much fun

 

[Nikodem]

512k chipRAM is double the memory of a regular A500, so it is a big fuss to get .

So you guys have rev.6a mobos - like me, I've got 8372A Agnus, and you?

For now I have added 512k RAM on-board to get 1M chip, but I still would like to have operational trapdoor slot to use it with KCS Power PC Board (and additional 512k of fast RAM). What to do? I know that there are some ways of obtaining such functionality (ReSlow od smt like that?).