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Baby Screamer Mark V-ish Boards

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First post, by Ailicec

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A few months ago, I picked up a Baby Screamer on Ebay. Got it, didn't work. Recently, I swapped out the 8042 and now it boots! Unfortunately, it won't boot with the cache chips in, so I went looking for more info.

It turns out there seem to be several revisions of the board, and they differ substantially. Component placement is similar, but the jumpers and cache vary. The ones I have to look at so far include the TH99 based one you'll find on stason.org, etc, and one linked from a thread here http://mail.lipsia.de/~enigma/neu/pics/386babyscreamer.jpg.

I have looked hard for a manual, and found none. There is a Baby Screamer LC manual around; it is considerably different (seems newer - wouldn't mind having one, with the 16 meg SIMM support it goes to 128 mb). Baby Screamer LC is series 62 and seems to autodetect RAM, and has a lot less jumpers.

Mine is a "Series 42" and there's a ECN14 (engineering change notice, probably). The one I linked is an ECN05. No idea what the TH99 one is.

What I've found so far:
Static ram cache setup:
TH99 - U38 is a 24 pin DIP, U36 is a 22 pin. Tag RAM of 16kx4 goes to U36 for 64k cache, or 64kx4 goes to U38 for 256k cache.
ECN05, ECN14 - U38 and U36 are 22 pin DIPs. For a 64k cache, U32 gets a 16kx4, U38 gets a 64kx1. Tag Setup for 256k cache is unknown.

TH99, ECN05 - Appear to be same jumper setup for cache - J19,J20,J32.
ECN14 - Unknown. Logically, J37, J50, J51 would be involved. J50 and J51 are 4-position jumpers.

Other jumpers -
ECN05 and ECN14 seem to be fairly similar. TH99 has almost all of them in different positions with non-correlateable numbering. Unfortunately, TH 99 is the only one with any definitions.

I realize the chances of getting anywhere with this are pretty slim, but maybe this info will help somebody else eventually.

Practical questions out of this are: What is the cache jumper setup, and do the later revisions support 16 meg SIMMs?

I could just have a bad cache chip, but its hard to say with the jumpers being in question. Also, trying the 256k upgrade is about impossible without knowing what jumpers/tag chips are needed.

Similar about the 16 meg SIMMs - I don't have any laying around, though I'm pretty sure that SW5-8 control RAM and with experimentation might figure those out.

Thanks again. Pic the board is attached for reference.

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Reply 1 of 5, by Ailicec

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I got some info from a very generous source. Here are the good bits:

Max memory on my revision is still 32 megs.

Jumper/ Location, 64 KB Cache, 256 KB Cache
J50, OPEN, Short pins 1-2 and pin 3-4
J51, OPEN, Short pins 1-2 and pins 3-4
U32, PRESENT, ABSENT

Jumper, 33 MHz, 40 MHz
J37, OPEN, OPEN
J35, Short pins 2-3, Short pins 1-2
U38, Present, Present

U38 is occupied by a 22-pin 64 KB x 1 SRAM with a 12 ns access time.

I have most of the manual, which I'll post if I can get it converted to a reasonable format.

Reply 3 of 5, by Tetrium

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dirkmirk wrote:

Onboard floppy & IDE? never seen that on a 386

Me nether, but it's there in the pic in the first post. Amazing...

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Reply 4 of 5, by Ailicec

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Yep, its nice. It has the usual limitations of the era that max out at about a 512 meg hard drive. There may be some software that can overcome that; would be nice to rig up a CF card with a gig or two. I don't think there was a way to get ATAPI (CDROM) stuff to work on an old BIOS though. The old sound card I have has a CDROM interface so I can still use them.

In general the BIOS seems ahead of its time - there are a lot more options. My 386sx with a Phoenix BIOS doesn't let you do much more than set the floppy and hard drives. This AMI one has a lot of speed settings, shadow ram, etc.

Another tidbit, my 386sx remaps the 384k from 640 to one 1 meg into extended memory. It must have complicated the memory controller some. I've had the thing 20 years but didn't realize it until now. That lets you have a 384k ramdrive or cache with just 1 meg of RAM. This AMI one doesn't, but has the shadow RAM, so it isn't completely wasted.

By the way, the cache these things take is REALLY hard to find. I finally got a few 16k x 4 15ns SRAMs that hopefully will fix this thing, but getting the 64k x 4s that would upgrade it to 256k cache seems very unlikely.

Reply 5 of 5, by Ailicec

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Here is the manual, as a medicore pdf and the original file. The original is WordPerfect with encapsulated postscript, and I haven't been able to get a decent conversion, except possibly to TeX, which I don't understand. I apologize for it not being great but it should answer most questions. If somebody manages a higher quality conversion, I'd love to see it.

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