Osborne-1 with prototype-based motherboard

There are definitely some differences. For example, the ROM BIOS on mine is contained on two 2716s instead of a single 2732 as in the later boards. There's a few jumper wires on the board too. I imagine it's largely the same, although if it were completely I'm not sure why they'd do a full redesign and not, like you said, use some of that extra space for more RAM or something. Lee himself didn't really know.. all he said was that that space, in the prototypes, was occupied by linear voltage regulators that were changed/designed out after. Maybe what I'll do is make a complete list of the ICs and see how it lines up with a later production board. And then compare other components. -----Original Message----- From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jules Richardson via cctalk Sent: Saturday, December 29, 2018 4:21 PM To: cctalk at classiccmp.org Subject: Re: Osborne-1 with prototype-based motherboard On 12/29/18 2:53 PM, Brad H via cctalk wrote: Is it just the board layout that's different, or does it appear to be a completely different animal, schematic-wise? (I mean, is there a possibility that the common schematics could still be used for fault diagnosis, despite the different chip locations) I wonder why the board layout changed? I mean sure there was a lot of unused space in yours, but it's not like the production boards were physically smaller. I'm surprised that additional space couldn't have been used for some other potential future purpose - RAM expansion or whatever. cheers Jules