Z80 / Z84C Swap (Doh!)

drlegendre . drlegendre at gmail.com
Mon Aug 17 15:20:57 CDT 2015

>From my inspection, it seems that this machine does have the DD option. The
tech manual mentions that the DD upgrade includes a small daughterboard
mounted on the mainboard, and the v1.4 ROM, which I assume contains the DD
driver code in the BDOS. Both a daughterboard (with a data cable to the
floppy drives) and the ROM are present in the machine.

By all appearances, it's a late version. The unit was sold the day before
Christmas in 1982. Based on their brisk sales at that point, the unit was
probably built within a few weeks of the sale date. It also has the final
two-piece molded plastic case with dark blue bezel.

To answer a couple of earlier questions - yes, I have a logic probe /
pulser set and a 20Mhz analog scope. First order of business is to get some
known-good media, before I start thinking too much about what might be
wrong with it.

On Mon, Aug 17, 2015 at 2:23 PM, Mike Loewen <mloewen at cpumagic.scol.pa.us>

>    The Executive shipped with CP/M Plus 3.0, in SSDD format.  The Osborne
> 1 required a double-density option to read DD disks.  I don't recall that
> the CP/M Plus 3.0 would even run on the Osborne 1, at least not on my
> systems.  Depending on whether the double-density option is installed on
> his machine, it might require someone with a system that will write a
> single-density boot disk for him.
> On Mon, 17 Aug 2015, Sean Caron wrote:
> ...
>> I have a mostly working Executive ... logic is OK but the screen will roll
>> when the environmental conditions are just right (probably some caps are
>> getting dodgy, or a cold solder joint) ... it's usable ... I have all the
>> original media and documentation; plenty of bootable floppies; I've got a
>> sleeve of 5.25" blanks and I could run off a few duplicates for you ...
>> not
>> sure if these will work on the Osborne 1 ... if you're in the USA and you
>> want to give some of the media from the Executive a shot, maybe I could
>> help you out.
>> Best,
>> Sean
>> On Mon, Aug 17, 2015 at 1:48 AM, drlegendre . <drlegendre at gmail.com>
>> wrote:
>> Thanks for the input, gents..
>>> Sigh.. and here I sit, yet again, with neither a logic analyzer nor a
>>> decent digital scope. Unless something comes up, looks like I'll have to
>>> do
>>> it the hard way, as usual - heh.
>>> At least the machine doesn't have a totally scrambled brain, with the
>>> correct CPU - so it will be easier to work through things, as I can at
>>> least partially communicate with the hardware if needed. Well, except for
>>> the lack of bootable media..
>>> Anyone have a spare Z-80? Or some bootable media for the Osborne 1? I
>>> have
>>> a few CP/M machines here, but I don't think any of them can write media
>>> for
>>> the Osborne. Even so, I'd need a way to get the Oz disk images to the
>>> machine of choice.. and that's another huge hurdle.
>>> Help a brother out.. I need some bootstrap media!! ;-)
> Mike Loewen                             mloewen at cpumagic.scol.pa.us
> Old Technology                          http://q7.neurotica.com/Oldtech/

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