RAM not showing on Viper 1230/28 RTC

[Zac67]

Has that SIMM worked on that card before? Have you tried another stick? Is it possibly EDO and not compatible?

[Zac67]

I don't have another one small enough. What would happen if I used a 16MB SIMM?

It might actually work (as 4 MB), but that depends on board layout and various detail. Can't really break anything so I'd try.

Is it possibly EDO and not compatible?

If it doesn't say on the RAM, is there any way to tell?

FPMs usually have somewhat descriptive numbers... What do the chips say?

[Zac67]

There is a sticker with a part number "11D1320BA-70". I have found some web sites which reckon it's EDO and some which don't... so I don't know whether it's compatible or not.

I guess that's the label on the SIMM itself (original IBM, probably EDO), possibly the chip code could provide better info.

I guess I have at least a dozen 4 MB SIMMs dug up somewhere, mixed EDO/FPM. If you think it'd be worth the postage, I'll take a look. BBoAH says it'll also take 8 MBs but probably only rare single sided ones?

[Zac67]

Ok, the chips themselves are labelled "TP014400J2C-70". Had a quick Google and can't find anything meaningful - but then I don't really know what I'm looking for!

xx4400 most probably means 4x1M FPM (8 chips?) - I'd venture that's one of the most compatible SIMMs on earth (as long as 70ns is fast enough).

Thanks! I'll try my 16MB SIMM and see what happens. If I still don't have any luck and it looks like the 4MB SIMM is incompatible then I might take you up on that.

Sure, be my guest. I'll check what I've got tomorrow.

I don't think a double-sided SIMM would fit.

That's what the card looks like - I'm pretty positive I've got NO single sided 8 MB.

[Zac67]

Sorry, forgot to look for the RAMs a couple of times.

OK, the single sided types I've got:
4 MB Micron 60 ns FPM (µT4C4007-6 chips)
4 MB LGS 60 ns FPM (GM71C17400-6)
8! MB HP 60 ns EDO (Fairchild 8117805-60)
4 MB LGS 60 ns EDO (GM71C17403-6)
4 MB HP 60 ns EDO (MH1M325-6)

So there's even a single sided 8 MB SIMM, but it's EDO.

If you're interested I could e.g. send you one of the 4 MB FPM ones and one of the 8 MB HP modules for testing. There are several of each type, so if you can use more than those, just tell me. PM your address and I'll check what the postage is. :-)