Re: PC as 1541

From: Gábor Lénárt <>
Date: Sat, 30 Apr 2011 11:20:48 +0200
Message-ID: <>

Btw, what came into my mind yesterday: what will happen if someone write an
emulator which emulates the hardware of an 1541 by software, and I use that
to run the content of a real CBM DOS ROM, etc. It would be quite compatible
then, even with fastloaders or whatever I can imagine ... Since the original
CBM DOS can be run on the "emulated" (but seems to be original from the
point of view of DOS) hardware. The only questions:

* Is a regular uC fast enough to do this emulation at the speed of a real
  1541 (CPU emulation, etc)?
* It would need to put disk image to somewhere and as far as I can see, it
  must be in low-level format (GCR, whatever ...). It requires "some"
  memory, which is more than most uC provides (the image itself could be
  read/written through USB for example). I guess it's about 200K of memory,
  and of course you must emulate RAM of the drive, content of ROM, also
  the emulation itself uses memory: it's a bit too much for an "average"
  low-cost uC, I guess ....
* Projects like 1541-III states that one advantage that since no mechanical
  parts, it can be faster than a real 1541-III with still using serial IEC
  bus "old fashioned" (no disk turbo, whatever). With an emulation I talk
  about, it must be emulated too and I am not sure if there is way to
  optinally switch off emulating delayes caused by the mechanical parts
  since I guess CBM DOS won't be too happy (I don't know if waiting for
  events are done with mostly 'hard wired' delay periods or it really
  checks status of various signals all the time to see if something happened
  or not yet)

It would also have the advantage that if emulation is good, it really feels
as an 1541 with all the hw compatibility. Ok, I know projects like 1541
Ultimate can be more superior in this area, and honestly: it's very
expensive (at least for me), and for home building something like that: I
doubt I can learn FPGA programming quick enough :) Using a uC or CPU or
whatever with some kind of emulation feels ugly, but often it's simplier ...

On Tue, Apr 26, 2011 at 10:01:07AM +0200, Gábor Lénárt wrote:
> Hi All,
> I would like to use my PC (running Linux ...) as an 1541 which can be
> accessed by CBM machines (C64 and C64 DTV - my DTV is already modded so it
> has got an IEC serial bus and it's tested: it works with a real 1541) as a
> regular 1541 drive.  I tried to google a bit but what I found was only the
> way to connect an 1541 drive to the PC, but I have different need: I want to
> to connect a CBM machine to my PC which acts like an 1541 (no additional
> software needed on the CBM machine side) then.  Has anyone an idea about
> this?  I have to build some kind of cable to connect for example parallel
> port of the PC to the IEC connector of the CBM machine, but since I could
> not find any project for this, I even don't know which cable should I build
> and what software I can use at the PC side.
> Thanks in advance,
> - Gábor
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Received on 2011-04-30 10:00:12

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