Attached to this post are the pictures of the above mentioned RAM expansion board.

Memory expansion card may be an EMS card. If so, the RAM on it wouldn't be counted at startup, just by programs that used it.

I never considered that since I have such limited experience with machines this old. If it an EMS board, that would make sense why the CMOS doesn't see it.

I've also been playing around with seeing what RAM I can get it to recognize just on the motherboard and found that it sees the 2MB sticks on the expansion card as 1MB sticks, which is why I was was getting errors when I tried to tell the CMOS setup that it had 8MB RAM.

I am also finding this board is VERY picky as to what RAM it is happy with. A couple websites that have some semi-comprehensible text that references only supporting 1MB and 4MB SIMMs, and requiring Parity sticks as well. Pretty much all the websites are referencing the same text, but to sum it up, the board only supports 1MB or 4MB sticks of RAM and if you are mixing capacities, you need to use the 1MB sticks in the lower number slots and the 4MB sticks in the higher number slots. This also likely explains why the 2MB sticks are seen as 1MB sticks...

I have a good fistfull of 4MB SIMMs that appear to be parity, but it wasn't happy with any of them. Its possible they're ECC and not parity. I was able to get an extra 4MB using my 72-pin to 30-pin converter, but even then I had to try a few different sets of 1MB sticks before it took.

Assuming that its an EMS board, is it worth messing with, or should I not worry about that on a 386 (when running newer versions of DOS)?

EMS can be nice for some things. A 386 can simulate it through EMM386, but hardware EMS is always faster.

Games that require it:
https://www.vogonswiki.com/index.php/List_of_ … hat_require_EMS

I believe Wolf3d can use EMS, but I'm not sure if it matters as long as you have enough XMS for it...

Thanks! I will keep tinkering and see what I come up with.

I remembered another stash of RAM that I recently got and found three sticks in there compatible with this machine, so now I am up to a whopping 20MB on board. 4x 1MB sticks, 3x 4MB sticks, plus 4x 1MB 30-pin SIMMs in an adapter.

I think my next step is going to see what storage I can come up with. I intend to use an IDE controller for simplicity sake, but there's where the config question for the IO card comes in... Pretty much all of the ISA controller cards I have also have two serial ports and a parallel port. I may end up assigning the ports on the IDE controller to COM 3/4 and LPT 2 to avoid resource conflicts.

Sounds like a boot disk is in order, but that will wait for another day... My dog is yelling at me to go to bed 🤣

I own this machine and have the usermanual + servicemanual. I can send you a copy.

The memory expansion board can be used to further increase the supported memory both at EMS but also XMS. It needs to be setup in the BIOS (which can be accessed with CTRL+ALT+INS at boot).

@vetz, can you upload the manual to Internet Archive, so that we can all use it?

Thanks!
- Alex

ajacocks wrote on 2023-11-12, 16:50:

@vetz, can you upload the manual to Internet Archive, so that we can all use it?

Thanks!
- Alex

Any good resources on how to best do it? Formats, how to include OCR and what not.

I used to with the zeniths,

The first card with C&T 82C206 chipset and ports, diagnostic LEDs, is a CPU bus to ISA bridge board. You need 2 bios firmware ICs, One is missing. Does this explain you have no boot?
The row of red LEDs indicates voltages (5V, 12V, -5V and -12V, power good), is present and other green LEDs is for POST report status. It is useful for diagnostic use.

Yes, it takes parity FPM 36 bits simms only, 80 or 70ns. Make sure the speed is 80 or 70ns. Zenith does use presence detection pins like IBM and Compaq does. 60ns can be modified into 70ns or 80nsby moving the presence detection zero ohm SMD components. Use the google to find the presence detection chart, you need multimeter.

Do not use EDO, or IBM simms with identical 9 chips per side, not compatible. You need either 8 chips with one odd chip per side or 8 chips with 4 chips per side, these are industry standard parity simms.

Also do not use 30 pin simm coverters. Not stable.

One more thing, you need to fix this also to get it booted.
You do have non-standard DS1260 Dallas IC, need to be modified to bypass the internal battery by finding the terminals and unbury both, and cut one pin in two, ONLY at battery side of, so you can connect directly to the terminal, to disconnect internal battery and use external battery. Would be smart to x-ray it to find which two pins for battery.

Or go to ebay and get a Dallas substitute IC with external battery using part number DS1260.

Cheers,

vetz wrote on 2023-11-12, 17:26:

ajacocks wrote on 2023-11-12, 16:50:

@vetz, can you upload the manual to Internet Archive, so that we can all use it?

Thanks!
- Alex

Any good resources on how to best do it? Formats, how to include OCR and what not.

On the software side there's a Linux app I really like called gscan2pdf that works well for processing scanned documents. On Windows there's NAPS2 (Not Another PDF Scanner).

Don't worry too much about OCR in the file, its a nice to have but if you're not set up to do that please don't let it be a barrier to uploading.

I really appreciate all the help with this!

pentiumspeed wrote on 2023-11-12, 20:12:

I used to with the zeniths, […]
Show full quote

I used to with the zeniths,

The first card with C&T 82C206 chipset and ports, diagnostic LEDs, is a CPU bus to ISA bridge board. You need 2 bios firmware ICs, One is missing. Does this explain you have no boot?
The row of red LEDs indicates voltages (5V, 12V, -5V and -12V, power good), is present and other green LEDs is for POST report status. It is useful for diagnostic use.

Yes, it takes parity FPM 36 bits simms only, 80 or 70ns. Make sure the speed is 80 or 70ns. Zenith does use presence detection pins like IBM and Compaq does. 60ns can be modified into 70ns or 80nsby moving the presence detection zero ohm SMD components. Use the google to find the presence detection chart, you need multimeter.

Do not use EDO, or IBM simms with identical 9 chips per side, not compatible. You need either 8 chips with one odd chip per side or 8 chips with 4 chips per side, these are industry standard parity simms.

Also do not use 30 pin simm coverters. Not stable.

One more thing, you need to fix this also to get it booted.
You do have non-standard DS1260 Dallas IC, need to be modified to bypass the internal battery by finding the terminals and unbury both, and cut one pin in two, ONLY at battery side of, so you can connect directly to the terminal, to disconnect internal battery and use external battery. Would be smart to x-ray it to find which two pins for battery.

Or go to ebay and get a Dallas substitute IC with external battery using part number DS1260.

Cheers,

The machine boots fine (mostly), but due to the dead battery in the Dallas chip it doesn't retain anything after powering off (which is expected). I am able to get into the BIOS setup and the onboard ROM Monitor.

At this point, the only unknowns for me are the jumper settings on the controller cards, and how to use that RAM board. I left the controller cards as they are and ended up not using that RAM board and instead put all the RAM directly on the motherboard. I suspect there may be a software driver require to enumerate that RAM board.

As for storage, I found that all three ESDI hard drives I have are in working order, so I went with installing two of them in it. The BIOS also auto-detects the drive parameters on them.

The only other fault I have come across is one of the 6178 SRAM chips on the cache board is bad and I have to run it without the cache installed, so it has been collecting dust as other projects have taken over my work areas.

I don't remember if I mentioned it previously, but I got this machine from a retired engineer that worked at Heath.

OtakuN3rd wrote on 2023-11-12, 22:11:

The machine boots fine (mostly), but due to the dead battery in the Dallas chip it doesn't retain anything after powering off (w […]
Show full quote

pentiumspeed wrote on 2023-11-12, 20:12:

I used to with the zeniths, […]
Show full quote

I used to with the zeniths,

The first card with C&T 82C206 chipset and ports, diagnostic LEDs, is a CPU bus to ISA bridge board. You need 2 bios firmware ICs, One is missing. Does this explain you have no boot?
The row of red LEDs indicates voltages (5V, 12V, -5V and -12V, power good), is present and other green LEDs is for POST report status. It is useful for diagnostic use.

Yes, it takes parity FPM 36 bits simms only, 80 or 70ns. Make sure the speed is 80 or 70ns. Zenith does use presence detection pins like IBM and Compaq does. 60ns can be modified into 70ns or 80nsby moving the presence detection zero ohm SMD components. Use the google to find the presence detection chart, you need multimeter.

Do not use EDO, or IBM simms with identical 9 chips per side, not compatible. You need either 8 chips with one odd chip per side or 8 chips with 4 chips per side, these are industry standard parity simms.

Also do not use 30 pin simm coverters. Not stable.

One more thing, you need to fix this also to get it booted.
You do have non-standard DS1260 Dallas IC, need to be modified to bypass the internal battery by finding the terminals and unbury both, and cut one pin in two, ONLY at battery side of, so you can connect directly to the terminal, to disconnect internal battery and use external battery. Would be smart to x-ray it to find which two pins for battery.

Or go to ebay and get a Dallas substitute IC with external battery using part number DS1260.

Cheers,

The machine boots fine (mostly), but due to the dead battery in the Dallas chip it doesn't retain anything after powering off (which is expected). I am able to get into the BIOS setup and the onboard ROM Monitor.

At this point, the only unknowns for me are the jumper settings on the controller cards, and how to use that RAM board. I left the controller cards as they are and ended up not using that RAM board and instead put all the RAM directly on the motherboard. I suspect there may be a software driver require to enumerate that RAM board.

As for storage, I found that all three ESDI hard drives I have are in working order, so I went with installing two of them in it. The BIOS also auto-detects the drive parameters on them.

The only other fault I have come across is one of the 6178 SRAM chips on the cache board is bad and I have to run it without the cache installed, so it has been collecting dust as other projects have taken over my work areas.

I don't remember if I mentioned it previously, but I got this machine from a retired engineer that worked at Heath.

IDT6178 is available on ebay. Both types are compatible, but is your SOJ or DIP package, take a picture of yours?

Cheers,

Here is the service manual for the Zenith Z-386/20/25 and 33 as well as compatible/tested parts list from Zenith on their models.

It should have information on memory expansion cards as well as pinout for the powersupply and lots of other neat information

This was scanned back in 2018, not entirely happy with the results, so that is why I havent made it public on Archive.org

https://www.dropbox.com/s/l4kv059x6alwdmh/201 … 659788.pdf?dl=0
https://www.dropbox.com/s/wh7t319kjq6wt01/201 … 859810.pdf?dl=0

vetz wrote on 2023-11-13, 00:57:

Here is the service manual for the Zenith Z-386/20/25 and 33E as well as compatible/tested parts list from Zenith on their model […]
Show full quote

Here is the service manual for the Zenith Z-386/20/25 and 33E as well as compatible/tested parts list from Zenith on their models.

It should have information on memory expansion cards as well as pinout for the powersupply and lots of other neat information

This was scanned back in 2018, not entirely happy with the results, so that is why I havent made it public on Archive.org

https://www.dropbox.com/s/l4kv059x6alwdmh/201 … 659788.pdf?dl=0
https://www.dropbox.com/s/wh7t319kjq6wt01/201 … 859810.pdf?dl=0

Thank you SO much, that is a huge help for me!

pentiumspeed wrote on 2023-11-13, 00:46:

IDT6178 is available on ebay. Both types are compatible, but is your SOJ or DIP package, take a picture of yours?

Cheers,

I don't really have a space to take the system apart to get a picture at the moment, but page 5-6 (PDF page 84) of the service manual that vetz posted references it.

Its a DIP chip, socketed at that. POST flags the chip as bad and calls it out by socket number. I swapped it with another one at a different location and the error followed the chip to the other socket.

Yes, I'm aware there's one person in the UK selling them on ebay, but they're about $30 USD each when you factor in shipping and taxes...

Factor in this rarity of this computer, you should just pay the lot of money for a cache chip to fix your rare computer and please modify the DS1260.

I need to tell you, compared to Compaq and IBM, and other high end 386 boards. I have easier time getting 486DX and 386DX parts for Compaq.

Yours is a truly rarity because was purchased rarely at very large price, say 6,000 CDN or more. Even back in the day, 386SX and DX was current computers (around 1990 to 1992) where I worked full time at Queens University, despite large Uni, I can count on at least 20 Zenith 386DX with cache, ISA or EISA computers.

Even the ebay and other auctions, Zenith 386DX computers in general are very, rare even in parts.

Cheers,

My DS1260 is luckily still working. Bought a new in stock part 10 years ago when I acquired the computer which still saves the settings 😀

There is a mention of using external battery source in the manual. Maybe something for you to check out.

I found the price list for this machine here in Scandinavia from 1992, and they were certainly on the expensive side compared to other brands.

My machine is the same board as yours that support 25mhz. Could you check your crystal if its 40 or 50mhz? The is a J102 jumper to change from 20 to 25mhz according to the manual, but my machine just locks up. I was hoping to upgrade to 25mhz or faster without using the soldering iron.

Thanks Vetz ! Those scans are not bad, a few pages could be straightened but very readable !

Horun wrote on 2023-11-13, 02:50:

Thanks Vetz ! Those scans are not bad, a few pages could be straightened but very readable !

Yes, I remember I was doing that at the office after workhours. The feeder I used didn't like the pages that much (they are double-sided) and I had to re-scan alot to tweak the settings. In the end I remember security came on their evening checks at 11pm and wondered what I was doing. I realized I'd spent too many hours on it already and just cut some short. I have many more manuals to Zenith models that were in sale around 1990-1991, so this is not all of it.

OtakuN3rd wrote on 2023-11-12, 22:11:

As for storage, I found that all three ESDI hard drives I have are in working order, so I went with installing two of them in it. The BIOS also auto-detects the drive parameters on them.

The only other fault I have come across is one of the 6178 SRAM chips on the cache board is bad and I have to run it without the cache installed, so it has been collecting dust as other projects have taken over my work areas.

Did you get any BIOS error on the cache?

Also, may you or someone else who owns a Z386 answer these questions?

1. Does your system take about 20 seconds to pass the self-boot tests after power-on before the monitor comes to life? For me the diagnostic LED's on the system-board takes this long to clear.
2. Do you have any issues were sometimes the self-boot tests fail to initiate and the system hangs on boot with none of the diagnostic LEDs turning off?
3. Does the J102 jumper to change CPU speed between 20 and 25mhz do anything on your system? If I change it on my board, I get no boot.
4. What kind of crystal is installed in your system (since you have the 25mhz variant and I only 20mhz)? I'd expect it to be 50mhz, but just want to confirm brand/type. An image of the crystal clock chips close to the CPU socket would be awesome.
5. Would you be able to provide some images of the ESDI controller board? Mine had been replaced with an Adaptec 1540B SCSI controller at some point in the machines life. I'm trying to restore my machine to original condition and need a better image to know what to look for on Ebay.

I have upgraded my CPU from Intel to a Cyrix 486DLC. Its still running at 20mhz, but cache is enabled and working. I also noticed that the BIOS in Adaptec 1540C SCSI controller is incompatible with this machine.