Mio Register Selection - Yamaha Mio Service Manual

Address
(HEX)
Set address A15-A8 for $D600 RAM
$D1E0 window. (LSB of sector number.)
Set printer data and SCSI/SASI data. True
$D1E1 logic for printer — Inverted for SCSI/SASI
bus.
General purpose outputs.
B[3..0] High RAM address,
sets address A19-A16.
B[4] 1 = Set SEL- true
$D1E2
B[5] 1 = Enable RAM access
B[6] 1 = Set STROBE- true
B[7] 1 = Enable Parallel IRQ
Set ROM enable and bank. Only
1 bit allowed set at a time.
$D1E3 B[2] 1 = Disk Interface ROM
or B[3] 1 = Seg 2 of setup MENU
$D1FF B[4] 1 = R:/P: Handler ROM
B[5] 1 = Seg 1 of setup MENU
All bits 0 disable the ROM.
$D1C0 Write ACIA transmit register.
Perform a programmed RESET on ACIA
(data is "don't care").
$D1C1
Write ACIA command register.
$D1C2
(see table 5-2)
Write ACIA control register.
$D1C3
(see table 5-3)
Write RAM. High address A19-A8 selected
$D6xx
by $D1E0/$D1E2.
MIO Service Manual
Table 5-1. MIO Register Selection
Register Operation
Write Read
Set RST- signal true (low). Resets the
SCSI/SASI bus. (RST- also true during
RESET)
Read data from SCSI/SASI bus. Data is
inverted.
General purpose inputs.
B[0] = SASI C/D-
B[1] = SASI MSG-
B[2] = SASI I/O-
B[4] = Printer FAULT-
B[5] = SASI BUSY-
B[6] = Printer BUSY
B[7] = SASI REQ-
Also clears RST- signal
IRQ sense bits + Misc inputs.
B[0] = RS-232 DCD line
B[1] = RS-232 DSR line
B[2] = RS-232 CTS line
B[3] = Printer BUSY- IRQ
B[4] = MIO IRQ (from 6551 or
Printer BUSY- IRQ)
Read ACIA receive register.
Read Status register (resets IRQ).
B[0] 1 = Parity error
B[1] 1 = Framing error
B[2] 1 = Overrun has occurred
B[3] 1 = Receiver reg. full
B[4] 1 = Transmitter empty
B[7] 1 = IRQ occurred
Read ACIA command register.
(see table 5-2)
Read ACIA control register.
(see table 5-3)
Read RAM. High address A19-A8
selected by $D1E0/D1E2.
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