Re: Parity Errors On A 286 Unitron U3911-V2 Mainboard
Posted on 2023-10-02, 14:40
What kind of PLCC sockets did you use? Something like this https://www.mouser.com/ProductDetail/Mill-Max … Cb0gRbYIg%3D%3D ? What PLCC you would suggest?
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-09-10, 17:56
maxtherabbit wrote on 2023-08-31, 16:05: I'm definitely right. I have a board with that exact same chipset. Find some 1MB modules with 9 physical ICs on them, trust me. Thanks for the advice! It helped. Problem solved. It works just perfectly with 9 chips SIMMs. 4 Mb now on the board.
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-09-10, 17:54
I'm not a complete noob in electronics. It’s not that I’ve never heard of impedance and tracks that serve as capacitance on the board. ;) But in my opinion, this is clearly not the case. This track comes out of the capacitor connected with the 9.6 Mhz oscillator which is connected to the WD IDE …
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-09-06, 16:43
BIOS
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-09-04, 21:14
I was looking for any evidence that the memory wait state really works and affects something. And found after being hooked to pin 30(RAS) and pin 66(ENDRAS) on the VL82C101. So it's definitely affecting but without positive results in general. Still having parity issues and waiting for 9 chips SIMMS …
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-09-03, 20:05
Also noticed quite a weird thing on the SBC...
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-09-03, 20:04
Update: with an oscilloscope and VL82C101 datasheet I could find which switch is responsible for the RAM wait-state. SW1.5-on/off = RAM wait state. on=low(0), off=high(1)
Re: Parity Errors On A 286 Unitron U3911-V3 Mainboard
Posted on 2023-09-02, 20:24
I tried it on my 286. Did not work. It looks like the parity check is hardcoded in the BIOS and can't be disabled. But if we trace the BIOS, then we can disable it programmatically and patch the BIOS. Probably this is the only way. But does it make sense at all? I mean disabling parity control. If …
Re: Parity Errors On A 286 Unitron U3911-V3 Mainboard
Posted on 2023-09-02, 20:09
This is quotation from the URL you posed "There are suspicions that parity can be disabled only by interfering with the circuit board, and the manufacturer does not provide the ability to disable parity." from Kir17 (07.04.2023,12:16). Very similar to the truth. It seems to be the same on my 286 SBC …
Re: Parity Errors On A 286 Unitron U3911-V3 Mainboard
Posted on 2023-09-02, 15:41
Can you suggest 1M 18 pins DIP DRAM chips? At least which you are having and used. Presently I could find only those: Siemens HYB511000A-70 DIP-18 (from your picture) Samsung Km41c1000bp-8 18-pin DIP 1 Meg 80ns Dram Samsung KM41C1000AP-8 1M CMOS RAM DRAM 41c1000 80ns DIP-18 NEC UPD421000C-70 …
Re: Parity Errors On A 286 Unitron U3911-V3 Mainboard
Posted on 2023-09-02, 05:28
Did you check the socket itself? Maybe somewhere the contact was not soldered well enough or peeled off?
Re: Parity Errors On A 286 Unitron U3911-V3 Mainboard
Posted on 2023-09-01, 16:42
Given that this VL82C101 installed into the socket may mean that it might be a potentially unreliable part. p.s. I have also a quite similar 286 MB based on VLSI. And now I'm torn by curiosity and want to try to upgrade it to 4 MB, maybe I will run into similar problems.
Re: Parity Errors On A 286 Unitron U3911-V3 Mainboard
Posted on 2023-08-31, 21:59
This is really odd. Memory data line failure at 2A0000-2AFFFF Memory address line failure at 120103, read EDED expected EDED Did I understand correctly that the BIOS during the memory test read what was expected, but perceived it as an error? Because EDED == EDED, isn't?
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-08-31, 15:55
It behaves oddly and unpredictably. Last night I booted that SBC into a plain DOS and everything worked just fine. This morning I can't even boot it without errors. You are probably right - this memory is not physically compatible with this SBC.
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-08-31, 14:20
I´m having a similar issue at the moment: I actually was wrong. We have very different problems. In my case, this seems to be a software problem. In your case, you are experiencing a real physical memory fault. Some of the chip on your board doesn't work as it should. And it should be easy to debug …
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-08-30, 23:49
Are all the contacts of the SIMM slots clean? Are all the solderings of the PLCC 84 chips beyond all doubt? SIMM contacts are fine, in the slot and on the SIMMS itself. But I cleaned them up just in case. Did not help. And also checked this memory on 386 DX40. Works great there. The weirdest thing …
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-08-30, 19:05
I actually could make it work with 4 MB of RAM. But unstable. Don't know why yet.
Re: ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-08-30, 18:48
Thanks! Yeah. It looks like Biostar. Didn't know that they also used VLSI chipsets.
ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V)
Posted on 2023-08-29, 22:55
Found a new artifact and would like to share it with the community. A gentleman from Ireland kindly sold it to me. ISA Intel 80286 Single Board Coputer MBVLSI-168 (UG-286V) Manufacturer most likely TOPTEK. Couldn't find the manual or jumper settings, but could figure it out step by step manually. …
Re: Memory Test tools for DOS ?
Posted on 2023-04-16, 16:29
done
Page 2 of 3