Re: Strange CBM710 with 3.5" drive

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Re: Strange CBM710 with 3.5" drive

Steve Gray
Hi Michal,

Did you ever dump the rom or do anything else with this strange floppy drive system inside the CBM-II 710 machine?

Just curious as the topic came up recently in my chat group.

Steve



From: Michał Pleban <[hidden email]>
To: [hidden email]
Sent: Friday, June 14, 2013 12:30 PM
Subject: Re: Strange CBM710 with 3.5" drive

Hello!

Christian Dirks wrote:

> So it was you who bid me out ... ;)

Oops, sorry. I started buying stuff again, so watch out for me! ;-)

> I wanted to see how the internal floppy drive works.

It is labeled "SMD-150". From what I was able to found on the net, it's
a floppy drive made by Epson, single sided, single density, 180kB
capacity. I didn't even know that single sided 3.5" drives existed? And
why someone would put such a low capacity drive on this mighty machine?

There is a 13-wire makeshift ribbon cable connected to the drive. This
might be a subset of a Shugart connector with only required signals. On
the other side it plugs into a small PCB attached to the expansion
connector. On the PCB there is an EPROM, a SAB2793B floppy controller,
two TTL chips and several discrete elements. I'll try to dump the EPROM
later.

A 4-pin connector is also soldered instead of the extra (otherwise
unused) power connector from the power supply and it powers the floppy.

> 'Elektronikladen Detmold' still exists: http://elmicro.com/
> Maybe someone there knows about the 'GDP 64K' ?

Thanks for the pointer, I'll send them email :-)

Regards,
Michal Pleban


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Re: Strange CBM710 with 3.5" drive

Michał Pleban
Steve Gray wrote:

> Did you ever dump the rom or do anything else with this strange floppy
> drive system inside the CBM-II 710 machine?

Unfortunately, no. The computer is sitting at the storage right now :-(

Regards,
Michau.