MFM floppy and HD emulator DREM

Guy Sotomayor Jr ggs at
Mon Oct 17 12:28:21 CDT 2016

> On Oct 17, 2016, at 10:23 AM, Josh Dersch <derschjo at> wrote:
> On Mon, Oct 17, 2016 at 10:21 AM, Guy Sotomayor Jr <ggs at>
> wrote:
>>> On Oct 17, 2016, at 9:58 AM, js at wrote:
>>> On 10/17/2016 11:18 AM, Peter Cetinski wrote:
>>>>> On Oct 17, 2016, at 11:58 AM, emanuel stiebler<emu at>  wrote:
>>>>> Hi all,
>>>>> anybody has any experience with that:
>>>>> ?
>>>> Yes, I'm currently in the process of getting the DREM working with a
>> Tandy 6000 and Xenix.  ...
>>> About $250?   Wish it were half that.  Seems like they could sell more
>> than twice as many at half the price, and more than 4 times as many at
>> 1/4th the price.
>> Really?  Come on guys, this stuff costs $$’s to produce and they may
>> actually want to make some profit.  If you’re doing small volume stuff
>> (10’s-100’s vs 100,000’s - 1,000,000’s) it’s going to be a bit pricey.
>> Frankly, to get the price to drop to half ($125), you’d probably have to
>> get 10x-100x quantity increase.  I know because I face the same thing when
>> trying to produce my boards.  Assembly will typically double the cost of
>> the board + components.
>> I’ll likely be getting at least 3 of them (1 for the IBM 3174 and 2 for my
>> Symbolics 3640 and possible another 2 for my other Symbolics 3640).
> Don't, at least not for the Symbolics gear.  The DREM only works with hard
> drive controllers it knows about, and the Symbolics ain't one of them.  I
> chatted with the developers about what it would take to support them and
> they see it as being possible, but couldn't commit to it without having
> hardware on hand to test with.  And given how hard it is to get a Symbolics
> machine to even format a disk once you have a working machine, it's not
> likely to happen anytime soon.

Sad.  :-(

That probably means it won’t work with the 3174 either.

It sounds like they’re not doing bit level capture/replay but actually trying
to emulate the actual format (ie knowing about how sectors and addressing
are laid out).  It make the end result (ie what’s on the SD card) a bit more
usable but it also makes the emulation dependent upon what controller is
being used.

TTFN - Guy

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