Re: C128D

From: Nicolas Welte (
Date: 1999-03-19 10:29:24

Ruud Baltissen wrote:
> A friend of mine has one. I cannot remember details but the 6522s and 6526 of
> the 1571 have been put in one single VLSI chip. But certain not needed
> registers have been left away. I have no experience but he showed me some copy
> PRGs which worked fine on the C128D, my C128/1571 combination but not on the
> C128DCR.

Actually they integrated parts of the MFM controller WD1772 and the
parts of the CIA 6526A into a new chip, the 5710. I once had a little
look at the memory map of this 1571CR drive and it is somewhat weird. It
looks like all the MFM and CIA registers are there, but some only act as
memory locations. Only the CIA shift register is needed, so I guess they
only implemented one timer and the shift register. The CIA mirror
locations mostly show what they should, but some address patterns don't
show a mirror image like they should. Maybe an internal bug in the 5710.

>From what I've seen from the hardware so far, I'd say that all software
should run and even the old 1571 ROM should work. 64'er magazine said
that this doesn't work, and I never tried it myself. And the software
incompatibilities you saw could be caused by the new ROM as well, and
not by the hardware itself. E.g. there is the Hexer 128 copy program
which exists in special versions for each of the 1571 versions: one for
the 1571 with ROM -03, one for the 1571CR, one for any 1571 with
DolphinDOS and finally there is a patch for the 1571 with ROM -05. The
patch is quite short and must be applied to the 1571CR version! I never
did this, because I mostly use the Dolphin version anyway and then there
is a fixed version on funet that runs on all three versions of the

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