Adds 6850 DCD status latch to M2SIO devices.
Adds vector interrupt support to M2SIO devices.
Removes CTS inactive transmit disable from PMMI device.
Adds IMSAI-style programmed output to CPU/SIO devices.
SET CPU PO will display "PO: AREG" upon an "OUT 0FFH"
instruction.
SET CPU NOPO will disable the function (default).
Corrects problem with Mode 0 interrupts.
When the CPU receives an interrupt, it pushes the current
program counter on the stack. The current implementation
of Mode 0 was performing interrupt processing after fetching
the next opcode from RAM, which also increases the PC by 1.
This caused PC+1 to be pushed on the stack. The interrupt
processing is now done prior to fetching the next opcode,
preserving the correct program counter.
This commit adds a "PMMI" device to the AltairZ80 VM that emulates
the PMMI Communications MM-103 MODEM & Communications Adapter.
This device was added at the request of a Facebook user that is
attempting to preserve and document various relevant communications
programs for CP/M and allow users to experience communicating and
sharing information with other remote computers of the same time
period, all on modern hardware.
This device attempts to emulate the MC6860L digital modem chip in
such a way that communications software written for the PMMI MM-103 can
communicate over a serial port or socket without a phone line or
the ability to MOdulate/DEModulate data over a phone line.
