Paul, Worst case you can borrow my copy of that laptop, swap parts until you find the bad component that way. Bill
On Tue, Jun 30, 2020 at 8:55 AM Paul Rickards via cctalk < cctalk@classiccmp.org> wrote: > Hi All, > > I'm restoring a Zenith MinisPort laptop, an 8088 based laptop with a > monochrome screen and 2" floppy drive. > > I have a Twitter thread of the restoration so far with pics: > https://twitter.com/paulrickards/status/1272280795529519105 > > I recapped the internal power supply board which seems to be working well > now. > > The next issue appears to be memory. The unit won't store the BIOS settings > properly, even with new lithium batteries or warm restart. In the BIOS > menu, setting the clock with a "0" changes to "32". Same with the date, if > you set the day or month, it adds 32 to it. > > The internal memory test reported a memory error at B800:0000 bit 5. This > seems to coincide with the BIOS "0" turning into 32 on screen. > > When it eventually boots from the internal MS-DOS 3.3 ROM, it looks fine > until the screen starts to scroll. The character case of all text on the > screen changes from lower to upper case. > > Anyone know how to map a bit 5 error to a component on the motherboard? > Would a memory map help here? > > Longshot: anyone have a service manual for the Zenith MinisPort ZL-1 (or > ZL-2)? > > Thanks, > Paul Rickards > biosrhythm.com >