On Thu, Aug 28, 2025 at 7:46 PM Bill Gunshannon via cctalk <[email protected]> wrote: > > > > On 8/28/2025 1:07 PM, Tony Duell wrote: > > On Thu, Aug 28, 2025 at 5:51 PM Bill Gunshannon via cctalk > > <[email protected]> wrote: > >> > >> > >> I finally got the missing keyboard and now it is time to try > >> and revive it. > > > > I restored one some months back. Mine is 100% IBM boards and options.... > > > > The portablePC has a normal XT motherboard in it. The standard video > > board is the CGA one, with the composite output (on the 4 pin > > connector originally designed for an RF modulator) feeding the > > internal amber moniitor. This is actually a Zenith unit. > > That explains the weird little cable stretching over some of the boards > and getting in the way. :-)
It's normally yellow and black twisted pair. As standard, the CGA card goes in slot 1, closest to the PSU. Floppy controller in slot 3. This leaves slot 2 as an empty full-length slot and slots 4-7 as half-length ones. Slot 8 is not really useable. Being an XT motherboard, the card there has to assert the buffer enable pin on reads. The only IBM card that will do that is the async serial one. And it's about 1/4" too long to fit, it fouls the power connectors on the drives. > > > > > Note that if you want to remove or open up the monitor and PSU you > > need Bristol Spline tools. > > Does it make me a true geek if I say that I actually have a set of them? > > > And tamperprrof Torx for the PSU cover. I > > had to take the latter apart, the mains input filter capaciitors were > > being antisocial and breaking down. I replaced them before they filled > > the worshop with magic smoke > > PSU seems fine. > > > > > > And how does the POST die? What error code, etc. > > Well, lets confuse things even more. Took th3e card out again and > the system tested all 640K and went into BASIC. Which is what you'd expect with no bootable disk in the system. > > What is the make and model of the hard drive itself? > > No idea yet as it is buried in the system below the floppy. But I > plan on pulling it out as soon as I figure out the mounting scheme > for the disks. I seem to remember you need a 5.5mm or 7/32" spanner and nutdriver to do that. You take off the earthing bracket on the right hand side of the drives towards the rear, then loose the other 3 screws on each drive and slide them out backwards. There are some useful manuals on bitsavers. The Technical Reference for the PC/XT and portablePC gives the motherboard schematic and BIOS source. The Options and Adapters volume 1 gives the schemaitcs for the drives and monitor. And volume 2 gives the CGA and floppy controller schematics (and lots of others). Finally there's the Hardware Maintenance and Service manual for the portablePC. This is a 'boardswaper guide' but it tells you what to unplug and what to unscrew to get things out. -tony
