4000D RevD RAM question

[Mrpond]

Hi Everyone, After 30 years away from messing around with Amigas I've picked up a 4000D with no Ram. I'm now a newbie! Can't remember a thing!

Question - Are fast ram and chip ram the same types/modules but allocated differently? I have 5 slots so can I use the same type of ram for all 5 slots,? Sorry about the basic question but I couldn't find a basic answer.

Thanks

 

[amienslaver]

In general, you need double sided stick for chip RAM (top slot), and then single-sided sticks for fast RAM slots. You can also put 8 MB on each second slot. Consider using FPM modules with latencies below 80ns, generally 60ns are best modules.

 

[Watson]

As far as I know / remember you can use 72-pin SIMMs for Chip RAM in an Amiga 4000D, but you need to use "dual-rank" SIMMs.
Typically double-sided and larger capacities like 2MB, 8MB, 32MB, or 128MB. Single-rank SIMMs will only be recognized as 1MB. The Chip RAM slot requires a 1 or 2 MB SIMM, while the Fast RAM slots can accept 1, 4, or 8 MB modules.

It's been a while so I be a little off.

 

[amienslaver]

You can use 8 MB double sided for chip RAM as well, but only 2 will be recognised (SIMM slots do not have all address lines physically connected).

 

[Mrpond]

As far as I know / remember you can use 72-pin SIMMs for Chip RAM in an Amiga 4000D, but you need to use "dual-rank" SIMMs.
Typically double-sided and larger capacities like 2MB, 8MB, 32MB, or 128MB. Single-rank SIMMs will only be recognized as 1MB. The Chip RAM slot requires a 1 or 2 MB SIMM, while the Fast RAM slots can accept 1, 4, or 8 MB modules.

It's been a while so I be a little off.

Thanks for the quick response Watson. I have 4x 4mb of Single sided ram and keep getting a dark grey/black screen. So because it's not double sided this could be an issue.

 

[Mrpond]

Thanks everyone now it makes sense to me

 

[amienslaver]

Thanks for the quick response Watson. I have 4x 4mb of Single sided ram and keep getting a dark grey/black screen. So because it's not double sided this could be an issue.

No, you can use single-sided stick for chip RAM, it would only detect 1 MB. Black/grey screen typically means problems with CPU.

 

[hese]

Actually you can use a single-sided 4MB stick for Chip RAM.
When you set the jumpers as following, J213 = 8MB and J214 = 8MB, you get full 2MB of Chip RAM.

 

[Mrpond]

Actually you can use a single-sided 4MB stick for Chip RAM.
When you set the jumpers as following, J213 = 8MB and J214 = 8MB, you get full 2MB of Chip RAM.

Thanks hese, that worked perfectly.

 

[amienslaver]

This is unofficial feature, designed for future chipsets. And Dave Haynie said it’s better not to play around with those jumpers unless you are fully understanding what you are doing. I would personally find a double sided stick for a few bucks and use the MB as it was intended.

 

[hese]

This is unofficial feature, designed for future chipsets. And Dave Haynie said it’s better not to play around with those jumpers unless you are fully understanding what you are doing. I would personally find a double sided stick for a few bucks and use the MB as it was intended.

This works just fine. I have been running such setup for over a decade without any problems. You can use a double-sided stick if you prefer but 4MB stick works the same nonetheless.

 

[amienslaver]

This works just fine. I have been running such setup for over a decade without any problems. You can use a double-sided stick if you prefer but 4MB stick works the same nonetheless.

Do you use the same setup or with variety of extension cards? I’m just curious if there any compatibility issues with external hardware. I was running my bare setup in this mode for a few months, but switched back to avoid unexpected surprises.

 

[hese]

Yes, I have used it with all kinds of hardware (accelerator cards, Zorro cards, ...) and there is no any difference between a 2MB stick or 4MB stick.

 

[Mrpond]

Hi Everyone, thanks for all your help.

I thought i would give you a little update. I was having problems booting and kept getting a grey screen, i couldn't even use diagrom 1.3. to get any further information. I thought it could be a ram issue and wanted to get that cleared up and your help has done that.
I have made some progress and after giving the motherboard a good look over i found two pairs of pins on ether sides of Bridgette touching so i separated both and can now boot into diagrom and as a precaution i replaced Bridgette anyway as i thought this could be responsible for my other issues. one of them being i can't boot from a floppy or hard drive and the floppy drive and hard drive led constantly on. I have run some tests, graphics, sound all look good and i can see the 2mbs of chip ram but can't see and any fast ram. I have ran a slow test on the fast ram and have lots or errors. I have also moved the ram around in different slots with no luck.

Thought i would mention I have had the dreaded battery damage and replaced most of the bits around the battery U891, U177, U976, R176, U178, U891 and repaired some trace damage I have also recapped the whole board and now Just wondering what way i should go now? do i start pulling other chips out and replacing them?

thanks

 

[amienslaver]

Did you check SIMM traces? In this regard Hafnium can be useful. LED traces are going very close to SIMM slots, could be also an indicator of damage. Corroded SIMM traces are quite common for battery leakage.

 

[Mrpond]

Did you check SIMM traces? In this regard Hafnium can be useful. LED traces are going very close to SIMM slots, could be also an indicator of damage. Corroded SIMM traces are quite common for battery leakage.

Hi Amienslaver, Wow that's a handy piece of kit and going to save a bit of time. thanks for the link, i have just purchased one.

 

[amienslaver]

It is a nice time saver for maintenance and repair Also note that some pins of the SIMM sockets are not connected in Amigas, hence some LEDs on Hafnium may not be on, though a slot is fine.