LC630 DOS Compatible supports 64MB SIMMs - 84MB total!

[jeremywork]

Were they FPM or EDO? I thought the DOS card took 64s, but only FPM?? Or something like that. Suddenly cursing my lack of 64MB SIMMs for testing.

I'll have to post back when I have that machine open again, but EDO vs FPM would make sense. For some reason I photographed every internal component other than the RAM I was installing I guess :/

 

[jeremywork]

So, has anyone pushed their 630 DOS system to the 196MB maximum that was discussed here? MicroMac claimed it was possible with their bigSIMMS products https://www.micromac.com/products/bigsimms.html.

Were they FPM or EDO? I thought the DOS card took 64s, but only FPM?? Or something like that. Suddenly cursing my lack of 64MB SIMMs for testing.

Confirmation of both points: yes, I had been using 64MB EDO SIMMs which explains why the DOS card didn't like them. Thanks for mentioning it!

And these SIMMs together achieve the full 196MB:

 

[AeSix]

So, droppin' a bit of money on some new RAM for my Performa 640CD DOS...
128MB double bank 72-pin 60ns FPM
64MB single bank 72-pin 60ns FPM
These are max for the 2 slot 630s. I'll find out in a week or so if it's the same for the 640!

Does anyone know the /actual/ max for the DOS card? I had a 32MB in it, but I've moved that to the Mac until I get the above sticks. We know 64MB FPM won't work in it (Thank you jeremywork!) But would 64MB of EDO work? 128MB?s

 

[jeremywork]

So, droppin' a bit of money on some new RAM for my Performa 640CD DOS...
128MB double bank 72-pin 60ns FPM
64MB single bank 72-pin 60ns FPM
These are max for the 2 slot 630s. I'll find out in a week or so if it's the same for the 640!

Does anyone know the /actual/ max for the DOS card? I had a 32MB in it, but I've moved that to the Mac until I get the above sticks. We know 64MB FPM won't work in it (Thank you jeremywork!) But would 64MB of EDO work? 128MB?s

64MB FPM should work in the DOS card, but EDO won’t (which is what I had tried.)

640s should be the same as two-slot 630s; the photo I posted was of my 640CD.

 

[AeSix]

My bad. I got FPM/EDO reveresed regarding the DOS card.
Thank you for clarifying! When I get the 128MB module, I'll plop that in the DOS card and see if it works.


Also, in theory, if a stick of 256MB, single sided, 60ns, FPM RAM were to be made/found - it could potentially be used in these Macs? That's probably impossible without some circuitry magic, but in theory possible?

 

[AeSix]

64MB FPM should work in the DOS card, but EDO won’t (which is what I had tried.)

640s should be the same as two-slot 630s; the photo I posted was of my 640CD.

So, I bought "64MB FPM MEMORY NON-PARITY 60NS SIMM 72-PIN 5V 16X32 SOJ OR TSOP" from ebay - works' well for the Mac. I tested it in the DOS card, and Windows only seen 16MBs - 1/4 of the total. I barely knew much about RAM back when these things were current, but could FPM w/ Parity potentially have a different result?

I also bought "128MB 72 Pin FPM Memory SIMM 5V 60ns" on ebay as well, which also works in the Mac (a full 196MBs! YAY!)
This also does /not/ work in the DOS card.

A couple months ago, I bought "32MB 72-Pin 60ns FPM SIMM Non-Parity Memory RAM 16-Chip Apple Macintosh PC UNIX" to use in the Mac for testing, as it came with 2x 16MB sticks total - 1 in the Mac, 1 in the DOS card. This 32MB FPM /does/ work in the DOS card

2x 16MB SIMMs 8+4 chips, all "IH5117400-6" with a double-height P to the left, made March '97 with "USA" on the chips, but:
the module reads "810-44-3568 / Made in Taiwan"

 

[Phipli]

So, I bought "64MB FPM MEMORY NON-PARITY 60NS SIMM 72-PIN 5V 16X32 SOJ OR TSOP" from ebay - works' well for the Mac. I tested it in the DOS card, and Windows only seen 16MBs - 1/4 of the total. I barely knew much about RAM back when these things were current, but could FPM w/ Parity potentially have a different result?

In this case Parity wouldn't help. Parity is for error checking in computers that support it.

Sadly same size SIMMs were available in different configurations in that era - there were various refresh rates as well as sometimes, sort of, the same size might be made up of different numbers of rows and columns, or different numbers of banks of RAM. Its an absolute nightmare.

Has anyone ever got a 64MB SIMM working in a DOS card? Sadly (and surprisingly) I don't own a single 64MB 72pin SIMM.

 

[AeSix]

My tests:

Module | Location	Other markings	Chip markings	Mac DR	Mac SR	DOS card
16MB*	810-44-356B (PCB)	P IH5117400-6 | 9703 USA
32MB DR FPM NP	11153-0001 032M TECHWORKS 9811414 (small sticker)	9810 S USA MT 4C4MB1 DJ -6
64MB SR FPM NP (16x32)	(HJ) M1 94V-0 (PCB)	SEC KOREA 822 KM44V16100AK-6 TCD030BB
128MB DR FPM NP	2129 (HJ) M2 94V-0 (PCB) CE 1543159 RoHS 23209 July, 2023 128MB / 72 PIN (sticker)	NEC JAPAN D42S65405G5 -A60-7JD 9918E9009

Listing out what I know works and does not so others might have a good idea of what to get

NOTE: the 16MB modules have chips on both sides, 8 on one side, and 4 spaced out weirdly on the other side. The chips are mounted with the chip legs in rows perpendicular to the SIMM slot.
The 32MB SIMM also have the RAM chips in a vertical orientation with the chip legs perpendicular to the SIMM slot.
My 64 and 128MB modules both have 2 rows of chips, with their legs parallel to the SIMM slot - the 64MB module having 8 chips on one side, and the 128 having 16 chips total. I know physical orientation *may not* have any affect on operation, but maybe? *shrug*

 

[AeSix]

In this case Parity wouldn't help. Parity is for error checking in computers that support it.

Sadly same size SIMMs were available in different configurations in that era - there were various refresh rates as well as sometimes, sort of, the same size might be made up of different numbers of rows and columns, or different numbers of banks of RAM. Its an absolute nightmare.

Has anyone ever got a 64MB SIMM working in a DOS card? Sadly (and surprisingly) I don't own a single 64MB 72pin SIMM.

Everything I've read suggests 32MB is the absolute most the DOS card can handle. I don't know if that's actually true or not. Everything I read about my P640CD is 52MB max limit (4+32+16) and yet I've got it up to 196MBs!

I have found 64MB modules that are single sided and with the chips oriented so the chip legs are perpendicular to the SIMM slot. The one I have/tried is 16x32, the one I'm looking at is 16x36 (which apparently means it's parity ram... makes sense) It's $20, so worth a shot. I'm sure I have an old PC that'll take it if it don't work in the DOS card.

btw, when I put the 64MB Single sided, non-parity FPM in the DOS card's slot, Windows 95 seen it as 16MBs only.

 

[Phipli]

Everything I've read suggests 32MB is the absolute most the DOS card can handle. I don't know if that's actually true or not. Everything I read about my P640CD is 52MB max limit (4+32+16) and yet I've got it up to 196MBs!

I have found 64MB modules that are single sided and with the chips oriented so the chip legs are perpendicular to the SIMM slot. The one I have/tried is 16x32, the one I'm looking at is 16x36 (which apparently means it's parity ram... makes sense) It's $20, so worth a shot. I'm sure I have an old PC that'll take it if it don't work in the DOS card.

btw, when I put the 64MB Single sided, non-parity FPM in the DOS card's slot, Windows 95 seen it as 16MBs only.

Parity has nothing to do with whether or not a SIMM works in the DOS card - don't buy it. Spend the money on a pizza and a few beers instead.

 

[AeSix]

Parity has nothing to do with whether or not a SIMM works in the DOS card - don't buy it. Spend the money on a pizza and a few beers instead.

Like I said, not exactly a waste - I've got other retro projects to work on, and will have use for more RAM.

Anyways, it came in today. I got it installed... annnnd 16MBs seen by the DOS card. I'm not sure if it's seeing the chips at 512K each, or what.
I was hoping the different arrangement and chip capacity would change the outcome, but alas, I've now got a spare 64MB stick to plop into another machine lol.

Seems odd that it would downrate 64MBs to 16MBs instead of capping out at 32MBs. I wasn't a PC person back when EDO and FPM were "current" and wasn't very technically inclined (comparatively, to others my age, I was considerably more technical) But yeah, is that common behavior? In SDRAM days, I had a PC that had 512MBs (2x 128, 1x 256) but would only ever show 384. Just truncated the 256... but thinking about it now, was probably the eMachines or Gateway (I forget the brand) BIOS artificually limiting the RAM.

EDIT:
So, out of S&Gs, I installed this 64MB stick into the Mac, second slot (single rank slot)... and the Mac is using all 64MBs. The single sided 64MB I bought for the Mac, is in the dual rank slot... bringing a total of 132MBs. I assumed since the chips were on each side it'd be dual rank, specifically what the Mac cannot use in second slot. Different physical layout, same logical/electrical layout as the other module though. Oh well.