Drive I/O ports

 

PC Sun Amiga Texas Instruments
PC IDE Sun Floppy Amiga external floppy TI-99/4a Cassette port
PC FDD      
50-Pin High-Density external scsi port      

IDE

Looking at ide bus on drive.

Floppy drive (FDD)

SUN Floppy drive connector

Pin Name
1 GND
2 FD_DENSEL
3 GND
4 33_W_to_VCC
5 GND
6 FD_DRATE0_MSEN0
7 N/C
8 FD_INDEX_L
9 GND
10 MTR0_L
11 GND
12 FD_DRV1_SEL_L
13 N/C
14 FD_DRV0_SEL_L
15 GND
16 FD_MTR1_L
17 MSEN1
18 FD_DIR_L
19 GND
20 FD_STEP_L
21 GND
22 FD_WR_DAT_L
23 GND
24 FD_WR_GATE_L
25 GND
26 FD_TRK0_L
27 MSEN0
28 FD_WR_PROT_L
29 GND
30 FD_RD_DAT_L
31 GND
32 FD_HD_SEL_L
33 GND
34 FD_DSK_CHNG_L

Amiga External Disk drive connector

at computer
Pin Name Description
1 /RDY Disk Ready
2 /DKRD Disk Read Data
3 GND Ground
4 GND Ground
5 GND Ground
6 GND Ground
7 GND Ground
8 /MTRXD Disk Motor Control
9 /SEL2 Select Drive 2
10 /DRES Disk Reset
11 /CHNG Disk Removed From Drive-Latched Low
12 +5V +5 Volts DC (250 mA max)
13 /SIDE Select Disk Side (0=Upper, 1=Lower)
14 /WPRO Disk is Write Protected
15 /TKO Drive Head position over Track 0
16 /DKWE Disk Write Enable
17 /DKWD Disk Write Data
18 /STEP Step the Head-Pulse, First low, then high
19 DIR Select Head Direction (0=Inner, 1=Outer)
20 /SEL3 Select Drive 3
21 /SEL1 Select Drive 1
22 /INDEX Disk Index Pulse
23 +12V +12 Volts DC (160 mA max, 540 mA surge

Cassette TI-99/4a port
At the computer
At cassette cable
Pin Name Dir Comment
1 Cass 1 motor control OUT CRU bit 22
2 Dito OUT neg
3 Output to tape 2 OUT CRU bit 25
4 Audio gate OUT CRU bit 24
5 Output to tape 2 OUT neg
6 Cass 2 motor control OUT CRU bit 23
7 Dito OUT neg
8 Input from tape 1 or 2 IN CRU bit 27
9 Dito IN neg

50-Pin High-Density external scsi port
1 GROUND 26 –DB(0)
2 GROUND 27 –DB(1)
3 GROUND 28 –DB(2)
4 GROUND 29 –DB(3)
5 GROUND 30 –DB(4)
6 GROUND 31 –DB(5)
7 GROUND 32 –DB(6)
8 GROUND 33 –DB(7)
9 GROUND 34 –DB(P)
10 GROUND 35 GROUND
11 GROUND 36 GROUND
12 (Reserved) 37 (Reserved)
13 OPEN 38 TERMPWR
14 (Reserved) 39 (Reserved)
15 GROUND 40 GROUND
16 GROUND 41 –ATN
17 GROUND 42 GROUND
18 GROUND 43 –BSY
19 GROUND 44 –ACK
20 GROUND 45 –RST
21 GROUND 46 –MSG
22 GROUND 47 –SEL
23 GROUND 48 –C/D
24 GROUND 49 –REQ
25 GROUND 50 –I/O

Note: A plus sign (+) preceding a signal name means the signal is active high. A minus sign means the signal is active low.