Créé par Avery Lee (l’auteur de VirtualDub), il s’agit d’un émulateur d’Atari 8 bits (800/800XL/130XE) disponible en 32 et 64 bits. Il dispose de beaucoup d’options ainsi que d’une bonne compatibilité. Il prend en charge les jeux protégés conformément à l’émulation. Il s’agit d’une version de développement au stade de béta.
– Adds full XF551 emulation. As usual, you need an XF551 firmware for this to work. The version I tested with is revision 7.7, with CRC32 38B97AE3. High-speed, double density, and double-sided disks are supported.
– There are a couple of interesting things about the XF551’s firmware. First, it is unusually strict about the timing of the SIO COMMAND line in that it will not accept a command if /COMMAND is not still asserted through the end of the last byte, which most other drives don’t check. Currently the emulator stretches the command pulse a bit to work around some timing issues in the transmit path.
– The second issue is the way that the XF551 switches densities. As far as I can tell, the XF551’s density switching strategy is kind of FUBAR in that (a) it will only auto-switch to DSDD, never SSDD, and (b) it only switches to DD if it sees a long sector on a sector read other than a boot sector. The latter causes problems because while the drive successfully switches from SD (FM) to ED (MFM), it will fail to switch from ED to DD if the ED track/sector mapping causes a record not found error from trying to read a sector >18 instead of the lost data error. This happens if a picoDOS is booted or SpartaDOS X attempts to read a MyDOS disk. Would be interested if anyone has seen different behavior on a real drive on stock firmware; I’ve gone over the firmware many times and haven’t found a way for the drive to successfully switch to double density when only sectors 1 and 361 are read.
