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Intel 386 with Phoenix 1.3 BIOS - config error

falter

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Hi there,

So I have this Intel-branded 386 PC. I think it was a reference design - the labels suggest it was part of a custom run for some application or other. I believe it's a 386SX and the bios is Phoenix 1.3d. It didn't come with RAM, so I borrowed 8 256kb sticks from one of my expanded RAM boards.

Naturally the clock is dead. When the machine comes up, I have to switch on the keyboard lock (it requests it), before I can go into BIOS and change settings.

I've put everything in correctly to the best of my knowledge. The drive is an 80MB maxtor. However it still comes up with a configuration error message after I 'save' (obviously with no battery it will lose all settings on power down, but it does hold them while powered up). It is showing 512KB base and 1280Kb extended memory. It did actually complain about the memory once, but otherwise the message usually just says configuration error.

The machine will boot off floppy. I can see and read and use any of the contents of the hard drive. But it will not boot from HDD. The HDD does seem to have DOS and system files installed. The machine seems to have been used in a design environment - there's a lot of cad software and Windows 3.0 installed.

If anyone has any thoughts on how I can get it to boot to C: that would be awesome. It's been three decades since I was doing this stuff daily and i've forgotten a lot.
 
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Just replace the cmos battery. It's fairly common for early systems not to boot correctly or show other misbehaviours as long as the battery isn't working.
 
After you fix the battery and if it still does not boot, figure out what flavor DOS you have and then boot with a DOS system floppy and do FDISK /MBR then run SYS C: Also, select the correct boot order in the BIOS if there is an option for that.

P.S. So much for culling the herd, eh. :rolleyes:
 
Haha.. well, actually the herd has thinned a bit as I have sold some more stuff. But this machine I've had for a while.. just never bothered with it. I like thr plain case design, and it seems to be an actual Intel branded PC.

But mainly I got it because I never had a 386 back in the day and didn't have one after. I had to wait in 286 purgatory until prices came down enough that I was able to go to a 486.

https://drive.google.com/folderview?id=1Crgs-HJo73C419ebgHxpTcYGO-cY1h13

But yeah.. it seems to hold the settings I put in with power applied.. just keeps complaining about being misconfigured.
 
But yeah.. it seems to hold the settings I put in with power applied.. just keeps complaining about being misconfigured.
It's not really holding the settings. It will set the chipset registers etc. based on what you set in the BIOS, but the CMOS itself does not save anything. That's why you get the configuration error. The state of the system doesn't match the empty/garbled CMOS and is hence "misconfigured".
 
Interesting. I changed the SIMMS around. I am borrowing from an IBM memory expansion card thst came with my XT286, one that I presumed was not working. It had mostly the same density 256kb modules but had a couple of modules with two high density chips (so 2 small chips for 256kb rather than 6 or 8).. when I pulled those out the RAM count came out wrong (says 640kb, no extended.. but should have at least 384 extended right?). But it isn't complaining about misconfiguration. Maybe bad RAM was what was causing issues with that card.

One very strange thing though.. it *is* holding the settings for a time, even with battery disconnected and power cord removed. I had it unplugged for a full ten minutes while I was copying files from the hard drive.. I came back and it powered up with the same custom HD settings I'd put in there. I don't know how that happened but I'm positive it had no source of power for at least 10 min.

FDISK and format seems to have gotten C to boot again. I'd be fine leaving it without battery and entering bios info in. Except it wants you to lock the keyboard every first start.. and of course while I once was throwing out those keys left and right now I cannot find a single set.
 
Okay I don't get this.

I had this PC *totally* unplugged, battery removed.. the whole nine yards... and it *still* retained the settings I put in yesterday?!?

Other weird stuff. There are 8 SIMM slots. If I put RAM in the first four and configure for 640k, there's no error. But I would have thought 4x256 means you'd have 640 + 384 in extended? It says zero for the latter. If I add two more sticks, the machine will not post properly. If I add two more after that, it will post.. but it comes up with 640k base RAM and 1280K extended, and then puts up a memory config error. No matter how I change it (you can adjust the base ram between 512 and 640 only), it says error. I don't know if a slot is bad, or the RAM is bad.. I've tried swapping in different sticks in the first four slots and it always works fine that way.

I need to find a manual or something.. it's been a long time since i messed with SIMMs.
 
I seem to remember some 386 and all 486 systems required 30 pin simms in sets of 4 for the 32 bit bus. I think 30 pin simms are only 8 bits per simm.

I remember a board, not sure if it was 386 or 486. 1 Meg in the first 4 slots would only ever give 640k, but as soon as the second set was populated, the computer would recognize the extended memory in the first set of slots.

Also the BIOS holding settings for 10 minutes is not that unusual. It takes very very little power to keep BIOS settings and all of the decoupling caps on the board may have enough combined capacity to keep the chip up for even an hour or two!



NB: my memory of all of this is from a long time ago, a LONG time ago.
 
I seem to remember some 386 and all 486 systems required 30 pin simms in sets of 4 for the 32 bit bus. I think 30 pin simms are only 8 bits per simm.

I remember a board, not sure if it was 386 or 486. 1 Meg in the first 4 slots would only ever give 640k, but as soon as the second set was populated, the computer would recognize the extended memory in the first set of slots.

Also the BIOS holding settings for 10 minutes is not that unusual. It takes very very little power to keep BIOS settings and all of the decoupling caps on the board may have enough combined capacity to keep the chip up for even an hour or two!

NB: my memory of all of this is from a long time ago, a LONG time ago.

It's kind of scary isn't it? Like I was doing this stuff just yesterday and now *blink* it was 30 years ago. I don't think I ever boosted the RAM on my 286. I remember having trouble with SIMMS with my 486 and some requirement for pairs. Can't remember if those were 30 pin or 72 pin but I had a heck of a time getting that first 486 board to post properly. Once I did though - Desqview + Telegard + 8MB = multiline BBS baby.

There must be some serious juice in these caps.. that was 8 hours it sat unplugged!

But yeah.. if I stuff all 8 slots with 256k chips it complains there's a memory config error. But the only thing you can change is to set the base either to 512 or 640. Doesn't inhibit the thing from working - just annoying.

I really need to get a VGA CRT again. Doesn't feel authentic on an LCD.
 
I seem to remember some 386 and all 486 systems required 30 pin simms in sets of 4 for the 32 bit bus. I think 30 pin simms are only 8 bits per simm.

You're mostly correct. 30 pin SIMMs are 8 bits wide, but on 386SX machines, you only need two sticks to make up the narrower 16 bit bus. A 386DX and 486 will need four 30 pin SIMMs or one 72 pin SIMM to make up the full 32 bit bus.

The reason that 1 MB of memory shows up as 640k is because the upper 384k is reserved for memory mapped system peripherals, and that area is not addressable as system memory normally and is effectively lost. Things like the Video BIOS (CGA, MDA, EGA, VGA), System BIOS, ports (COM/LPT) and a few other things exist in the upper 384k.

It is possible with third party programs to remap unused portions of the upper memory area in the 640-1024k area to be used as conventional memory. FreeDOS can do this automatically and I've had up to 736k of conventional memory available on some machines.

The reason for the strange memory mapping is to be backwards compatible with the 8086, which only had a 20 bit address bus. The system devices had to be mapped somewhere in the address space, so the upper 384k was used.
 
I remember a board, not sure if it was 386 or 486. 1 Meg in the first 4 slots would only ever give 640k, but as soon as the second set was populated, the computer would recognize the extended memory in the first set of slots.

386 and later machines typically use the "missing" 384KB to allow the BIOS and any expansion card ROMs to be copied at boot time into 32bit wide RAM, from which they can execute much faster than from EPROM/flash. There are normally some "shadow ram" options to control this in the BIOS.

My 286 motherboard doesn't have shadow ram so the 384K is available for general use above 1MB. Well I say general use, its of rather limited use thanks to DOS limitations. The motherboard uses two EPROMS in parallel to match the older 16bit data bus width and older VGA cards do the same.
 
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