Does it still work if you put the video card back were it was, to the top slot of the riser? Sorry if I'm asking the obvious.

konc wrote on 2024-07-30, 17:15:

Does it still work if you put the video card back were it was, to the top slot of the riser? Sorry if I'm asking the obvious.

hehe that's okay. No it doesn't work. I wish it did!

I just got a similar ZDS 3797V1 board up and running and it was my introduction to how fussy these Zeniths could be! My board has diagnostic LEDs on the riser, are yours lit?

There is a newer BIOS and some service manuals posted in my thread that vetz was kind enough to scan.

Many Bothans wrote on 2024-07-30, 18:47:

I just got a similar ZDS 3797V1 board up and running and it was my introduction to how fussy these Zeniths could be! My board has diagnostic LEDs on the riser, are yours lit?

There is a newer BIOS and some service manuals posted in my thread that vetz was kind enough to scan.

Wow I wish I checked this place regularly 🤣. I bought several of these Zenith machines (there might be motherboard revisions, haven't checked that) a few years ago and only now getting around to refurbishing them. I'm going to go and comment on your post.

Regarding the diagnostic LEDs on the riser: I get two different sets of lights depending on how I have the jumper for J301 set:

In the first picture here, all these lights you see lit up blink. The parity light never comes on.

In this second picture these lights are lit up and stay solid. The other ones do not come on. Nothing blinks.

It's so weird that the manual does not get into detail as to what exactly these lights mean. If they are off, is that good? Who knows!

Interesting development: I went downstairs today and tried the computer again and the lights were different. This time they were all lit up except for INT.

I probably had the machine going for.... 20-30 seconds while I looked it over then turned it off. When I powered it back on the lights went back to the way they were in the picture above.

Where it's a time thing like this.... could that indicate a capacitor problem?

Could be, although what it really sounds like is bad contacts somewhere. If you've already worked on the SIMM slots themselves, it might be bad traces anywhere between RAM and CPU, or bad connection of the CPU itself. I think this board has a socketed CPU, so I'd check/deoxit that as well.

Check down in the slot you moved the vid card to with a flashlight in case it smushed down a contact to touch another, or introduced a sliver of circuit trace or peeled plating or solder debris or something. But yeah, board flexing when moving stuff can just be random as all hell for making things lose contact in sockets and opening up solder cracks etc.

"the bottom slot is reserved for the video card."

I have a board where the manual states: "FOR 5V CMOS ISA CARD, PLS insert in Slot7"

Have you tried a different graphics card in the correct slot? Or this card in a different computer?

ux-3 wrote on 2024-08-01, 19:28:

Have you tried a different graphics card in the correct slot? Or this card in a different computer?

just went down and tried this but it did not work.

BitWrangler wrote on 2024-08-01, 19:10:

Check down in the slot you moved the vid card to with a flashlight in case it smushed down a contact to touch another, or introduced a sliver of circuit trace or peeled plating or solder debris or something. But yeah, board flexing when moving stuff can just be random as all hell for making things lose contact in sockets and opening up solder cracks etc.

When I try to boot the system without even without the riser card I get the same error. I'm not ruling it out but I found out something else interesting today.

I found a service manual for a very similar Zenith 386 in another thread. In that manual it details the power-up sequence

See that part over the on side where it says slushware error? It says beep and flash. My diagnostic lights are flashing, and the speaker is beeping. I'm thinking that's my problem right there. The service manual defines slushware:

Slushware — a reserved area of system memory (OEOOOH -~ OFFFFFH) is used to store the BIOS ROM information and BIOS information for installed video cards. This information is copied during system powerup and write-protected. Storing the BIOS information in slushware reduces data access time.

...BIOS information and installed VIDEO CARDS. This can't be a coincidence that my perfectly fine system stopped working when I moved the video card around. What do you guys think? I have no idea how to fix a "slushware" error.

I think they were trying to be cute about a name between firm and soft, and they mean what is now referred to as ROM shadow. So, either there's an error in that memory range, due to hardware fault or something or your current video BIOS is too big to fit in the shadow ROM area, if it's not the original card.

Just to ask the obvious, what kind of expansion card did you try to insert and did you remove it afterwards when this problem started? Also have you tried a different video cars?

The CPU LED is the first that should turn off (in DIAG mode) if the basic checks goes as they should. The CPU LED represents pass of clock signals, video, BIOS/slushware to memory and cpu registers

vetz wrote on 2024-08-02, 17:55:

Just to ask the obvious, what kind of expansion card did you try to insert and did you remove it afterwards when this problem started?

I tried installing a 16 bit ISA NIC. I did try removing it after the problem started and I put the video card back in the top slot (the way I had it when things were working) but the problem won't go away.

vetz wrote on 2024-08-02, 17:55:

The CPU LED is the first that should turn off (in DIAG mode) if the basic checks goes as they should. The CPU LED represents pass of clock signals, video, BIOS/slushware to memory and cpu registers

When in DIAG mode, all lights blink on and off except for parity.

Currently in check mode and CPU, RAM, Parity stay lit. The rest stay off. All the while that beep pattern I mentioned above keeps happening.

BitWrangler wrote on 2024-08-02, 17:41:

I think they were trying to be cute about a name between firm and soft, and they mean what is now referred to as ROM shadow. So, either there's an error in that memory range, due to hardware fault or something or your current video BIOS is too big to fit in the shadow ROM area, if it's not the original card.

I think I can rule out the video BIOS being too big because this video card I am using DID work before I moved it to another expansion slot.

I won't rule out a hardware fault but it just seems so unlikely. I literally just moved the video card and installed a NIC.

Error in the memory range hey? How would I go about fixing that?

P.S: should I change the title of the post to say "Zenith 386 refuses to boot after I moved video card to a different expansion slot" ? Perhaps that would be more accurate as I am no longer certain this is a RAM issue.

Yes, make sense to change the title of the thread.

I agree its most likely connected to the copy of ROM to memory. I'd try the following

- Reduce to 1 or 2 mb (depends if you have 1mb or 256kb sticks) of memory and swap the memory sticks in slot 0 and 1 bank 0. The roms are copied in the upper memory area (inside the 1mb of memory).
- Try another video card

I know both of these worked, but 30 year old hardware can break at any point unfortunately.

vetz wrote on 2024-08-02, 18:13:

Yes, make sense to change the title of the thread. […]
Show full quote

Yes, make sense to change the title of the thread.

I agree its most likely connected to the copy of ROM to memory. I'd try the following

- Reduce to 1 or 2 mb (depends if you have 1mb or 256kb sticks) of memory and swap the memory sticks in slot 0 and 1 bank 0. The roms are copied in the upper memory area (inside the 1mb of memory).
- Try another video card

I know both of these worked, but 30 year old hardware can break at any point unfortunately.

The system was at 2MB so I reduced to 1MB using four completely different RAM sticks that were known working but the problem persists.

I also tried another video card and that did not work. I tried it in the top slot as well as the bottom slot but no difference.

geiger9 wrote on 2024-08-02, 17:32:

ux-3 wrote on 2024-08-01, 19:28:

Have you tried a different graphics card in the correct slot? Or this card in a different computer?

just went down and tried this but it did not work.

What did not work? The original card in a different computer?

This can't be a coincidence that my perfectly fine system stopped working when I moved the video card around.

Probably not. But it may not have to do with the video card but perhaps the 'moving'. What about all these little extra wires on the board? Did one of those got loose?

80s stuff tho, things stop working because of slight board flex and then you need to reseat 50 chips in their sockets because one of them is being a bastard.

Update time. I have gone and pressed down on chips and slightly pushed around other things on the motherboard but no change.

I went and bought some 512kbit EEPROMs. I burnt a copy of the stock BIOS ROM to one of the chips I bought and I get the same behaviour so I know that the chips are fine.

Well I searched The Retro Web for BIOSes that supported my chipset. There were only three examples there (and then two of my own that I uploaded).

One BIOS was a hi and lo set of 64 kilobytes each. My motherboard doesn't support two BIOS ROM chips (it has two sockets but nowhere in any documentation can I find how to make the system use two chips instead of one).

Another was a Phoenix BIOS 1.0. I burnt that image to one my chips, installed it in the socket and the system acts as if no BIOS chip is installed. Nothing. No beeps, solid lights on the backplane diagnostic LEDs.

Another was a Zenith BIOS MFM-300 monitor, which was the stock one, but this was a later revision. Mine is 3.2C and this one was 3.6D. I tried this one in my machine and again I get the same results as I stated in the previous paragraph.

I read that there was a Landmark Diagnostic ROM that was 512 kilobit for AT class systems and my system is an AT class but the 512 kilobit ROM does not seem to be on the internet. It is not on minus zero degrees. I tried merging the two 256 kilobit ROMS but this did not work. I merged them using Winhex's unify feature (8 bit bytewise and interleaved) and also I used TRW's rom-check bot. Both resulted in the same file. I tried using this BIOS ROM but again, the system acted as if no BIOS chip was installed at all.

At this point I'm lost once again. Hoping someone has some suggestions for me.

Edit: After looking at several manuals/service manuals for very similar Zenith machines it appears that my exact arrangement and number of diagnostic LEDs do not match up. It's the BIOS that would do the tests and tell the backplane board which diagnostic LEDs to light up right? Is a viable option trying to figure out from the BIOS ROM what the different light configurations mean?

geiger9 wrote on 2024-08-27, 22:29:

Is a viable option trying to figure out from the BIOS ROM what the different light configurations mean?

yes, but very painful
1 you need to know where the leds are wired and how to reach them thru software
2 you need to completely disassemble the bios and learn how it operates OR modify one of PC emulators (for example box86) to find address of code doing just the diagnostics, then disassemble. Most likely IDE handling PAL chip is doing address decoding and triggering 74LS273, 74LS273 stores diag diodes state.

You could try CGA graphic card - those dont have any bios = no bios copying 😀
Im also of the opinion its mechanical - either as BitWrangler suggested bend pins or something cracked/lost connection.

rasz_pl wrote on 2024-08-28, 00:10:

yes, but very painful 1 you need to know where the leds are wired and how to reach them thru software 2 you need to completely d […]
Show full quote

geiger9 wrote on 2024-08-27, 22:29:

Is a viable option trying to figure out from the BIOS ROM what the different light configurations mean?

yes, but very painful
1 you need to know where the leds are wired and how to reach them thru software
2 you need to completely disassemble the bios and learn how it operates OR modify one of PC emulators (for example box86) to find address of code doing just the diagnostics, then disassemble. Most likely IDE handling PAL chip is doing address decoding and triggering 74LS273, 74LS273 stores diag diodes state.

You could try CGA graphic card - those dont have any bios = no bios copying 😀
Im also of the opinion its mechanical - either as BitWrangler suggested bend pins or something cracked/lost connection.

I see. Yeah that is way beyond my ken.

As far as the mechanical issue, it just seems unlikely that two of these exact same machines would fail in the same way. Sorry, did I post that up above? This is the second Zenith 386 with this issue.