[fuse-emulator-devel] Fwd: About WD1772/WD1770 emulation in Fuse

[Philip K. <ph...@sh...>]

[ Forwarding to the list with Javier's permission ]

---------- Forwarded message ---------
From: Javier Herrera <jav...@ya...>
Date: Thu, Jun 25, 2020 at 12:37 PM
Subject: About WD1772/WD1770 emulation in Fuse
To: phi...@sh... <phi...@sh...>


Hello Phillip.

I'm a Spanish enthusiastic of the ZX Spectrum and I have been looking for
some information about the PlusD interface, in order to modify the firmware
in order to replace the original WD1772 FDC with the WD1770 FDC
successfully, because the different step timmings. Finally I remembered
that your Spectrum emulator Fuse implements such as disk interface and I
thought maybe your fuse sources (wd_fdc.h, wd_fdc.c, plusd.h and plusd.c) could
be useful.

Two things have stood me out in your sources:
- The WD1770 in wd_type_t is always used instead WD1772, when called
wd_fdc_alloc_fdc.
Why?
- Inside this function, rates for the WD1770 are initialized to 6, 12, 20
and 20 ms, whereas rates are 2, 3, 5 and 6 ms for the WD1772. Is this OK?
Because looking for the WD1772 FDC specs, I've found that the rates are 6,
12, 2 and 3 ms (I mean, they are in a different order).

Could you explain something about these two questions? Thank you in advance.


Best regards,
Javier Herrera