FPM 60ns VS EDO 50ns

[Hyperspeed]

Here's an odd thought that occurred to me just now:

If Amigas cannot utilise the EDO feature of more recent SIMMs would they still benefit from the 50ns rating that these SIMMs occasionally boast?

Here are 4 URLs that discuss problems with EDO:
http://home.cfl.rr.com/eaa/MemoryTypes.htm
http://eab.abime.net/archive/index.php/t-3540.html
http://mail-index.netbsd.org/port-amiga/2003/05/21/0004.html
http://home.swipnet.se/~w-32234/ppcrulez/faq.html

The last reccomends FPM for overall compatibility, would anyone have an opinion here on this matter?

And finally, the first URL discusses that if your motherboard has gold contacts your SIMM should too, if it has tin contacts then the SIMM should have tin contacts.

?

[Zac67]

All depends on the RAM controller in question: if it doesn't like EDO, you're out of luck. Otherwise EDOs will work just as well.
If the RAM controller can take advantage of -50 RAMs, then these EDOs could actually run faster without making use of their EDO functionality. However, most old hardware has probably never been tested at that speed, so it's impossible to tell before you've tried.

And yes: the contact metal of the SIMM should match that of the socket. Mismatching metals form a galvanic cell that (very slowly) builds up an insulating oxide layer between the contacts, see Wikipedia for details.

[amigagr]

2 years ago i upgrade my blizz1260 from a 16mb 60ns simm to 2x32mb 50ns simms and the total speed of the blizz was a bit faster. i can't tell for sure if these simms are edo or not. now that i have 1x64mb 60ns and 1x128mb 60ns the total speed is a bit slower than with the 50ns simms like the old days...

[Hyperspeed]

I pasted a chart on another thread to identify DRAMs on a 72-pin SIMM:

http://www.amiga.org/forums/showthread.php?t=22053

This might help to see if your SIMM is EDO but some Micron DRAMs don't conform to the layout.

I'm surprised you thought the 2x 50ns SIMMs were faster as when you have two SIMMs on a Blizzard the thing should revert down to 70ns shouldn't it?

I know that the DCE SX32-Pro for the CD32 has a jumper allowing a 50ns SIMM. I've never personally come across a 50ns FPM but I do remember back in '95/'96 Amiga Format reviewing the Blizzard 1260 with a 50ns SIMM.

[amigagr]

here you can see these simms front/back. i always test the total speed of the amiga after a hardware or software (patches) update with sysinfo,aibb and a complex enough ray trace project of imagine 3d, so i can assure you about the difference in speed. it's not dramatic but it's real.

[Hyperspeed]

I wonder if it has something to do with the internal organisation or refresh rate of the DRAMs...

Those SIMMs look EDO to me, the DRAMs are ultra slim. Great for Blizzard boards so long as you get reliability from them.

[amigagr]

yes indeed :-)

[alenppc]

Actually the PPC accelerators were designed to take advantage of the EDO memory, but they are also compatible with FPM. That's why there are options in the cards boot menu that allow you to configure the memory.

[AmigaMance]

I'm surprised you thought the 2x 50ns SIMMs were faster as when you have two SIMMs on a Blizzard the thing should revert down to 70ns shouldn't it?

 :-o Is this true?
 I have one 60ns SIMM on my BPPC and i was planning to add another one in the second memory slot. But if they are going to be treated as 70ns modules, i'd better stay with one. What do you think?

[amigagr]

if you need more the speed than the total amount of memory...

[Framiga]

Actually the PPC accelerators were designed to take advantage of the EDO memory, but they are also compatible with FPM. That's why there are options in the cards boot menu that allow you to configure the memory.

are you sure? AFAIK the memory settings in CSPPC boot menu, are useful to avoid problems with EDOs, not to take advantage of it.

Correct me if i'm wrong.

[Hyperspeed]

According to some Phase5 thing I read, no Amiga accelerator utilises EDO for some techy reason. I would assume this means the Cyberstorm PPC 604 too!

Oddly the Picasso-IV (1996) uses 4MB of EDO for it's video memory.

I think the Blizzard PPCs early menu was to turn on precharge which would help dodgy Korean SIMMs work. It didn't allow Extended Data Out improvement.

And yes, a lot of people have a fetish with putting 256MB on a Blizzard 1230-IV "because it can" but they'll probably never use all that FastMem and it'll revert each SIMM to 70ns. Same for Blizzard 1240 and 1260.

As far as I know the Blizzard PPC has SCSI built in so only has one SIMM slot (?). Odd that a newer type of memory wasn't used for these boards...

One thing I'm thinking about now after having problems with SCSI transfers is that the A1200 trapdoor connector and the 'zebra' connector on the Blizzard 1260 are of different metals. This would mean the oxidisation problem would occur (rapidly given the uncooled nature of the 1260!).

[amigagr]

Hyperspeed wrote:
As far as I know the Blizzard PPC has SCSI built in so only has one SIMM slot (?).

no, it has 2 x 128 mb slots

This would mean the oxidisation problem would occur (rapidly given the uncooled nature of the 1260!).

no problem at all after of exactly 10 years of work :-)  :-)

[PG]

I have had a lot of trouble with EDO memory and Blizzard / Apollo boards.
Some work, some work but unreliable, some dont work at all.
Nowadays i use only FPM memory and have no problem.. :-)

[zipper]

Hyperspeed wrote:
According to some Phase5 thing I read, no Amiga accelerator utilises EDO for some techy reason.

Almost true. Except A1200xl and QuickPak 4060.