PCjs Machines

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Improved PC DOS 7.00 Support

PCjs v1.15.6 is a fairly minor update that fixes a few Floppy Drive Controller (FDC) issues and one CPU emulation bug that prevented PC DOS 7.00 from working properly.

There are also some Debugger improvements; for example, if you turn on “fdc” and “int” messages in the Debugger using the “m fdc on” and “m int on” commands, all FDC (INT 0x13) software interrupts will be logged, including descriptions and register values.

PC DOS 7.00 still can’t be setup from its specially-formatted 1.84Mb XDF distribution disk images, “PC DOS 7.00 (Disk 2)” through “PC DOS 7.00 (Disk 5)”, so your best bet is to boot from the 1.44Mb “PC DOS 7.00 (1.44M Boot)”.

Note that you must also use a fairly new 80286 machine configuration, like this 8Mhz IBM PC AT, in order to use 1.44Mb diskette images; previous models did not support 3.5-inch diskette drives, unless they had been retrofitted with a newer BIOS.

Jeff Parsons
Oct 23, 2014