RQDX1 Controller Module Cable signals. J1 Connector Signals J1 Pin Signal name 1 MFMWRTDT1 (H) (RD51 only signal) 2 MFMWRTDT1 (L) " 3 GROUND 4 HEAD SEL 2 (L) (RDXX ONLY SIGNAL) (reserved for future use) 5 GROUND 6 SEEKCPLT (L) (RD51 ONLY SIGNAL) 7 RD1 RDY (H) (RD51 ONLY SIGNAL) 8 WRT FAULT (L) 9 DRVBUSOE (L) 10 HEAD SEL 1 (L) (RD51 ONLY SIGNAL) 11 RX0WPTLED (L) (RX50 ONLY SIGNAL) 12 RD0 RDY (H) (RD51) 13 RX1WPTLED (L) (RX50) 14 RDVSL0ACK (L) (RD51) 15 MFMRDDAT0 (H) (RD51) 16 MFMRDDAT0 (L) (RD51) 17 MFMWRTDT0 (H) (RD51) 18 MFMWRTDT0 (L) (RD51) 19 MFMRDDAT1 (H) (RD51) 20 MFMRDDAT1 (L) (RD51) 21 GROUND 22 REDUCWRTI (L) 23 RD0WRTPRO (L) (RD51) 24 DRV SEL 4 (L) 25 GROUND 26 INDEX (L) 27 RD1WRTPRO (L) (RD51) 28 DRV SEL 1 (L) 29 DRV SEL 2 (L) 30 DRV SEL 3 (L) 31 RX2WPTLED (L) (RX50) 32 RXMOTORON (L) (RX50) 33 GROUND 34 DIRECTION (L) 35 GROUND 36 STEP (L) 37 GROUND 38 RXWRTDATA (L) (RX50) 39 GROUND 40 WRT GATE (L) 41 GROUND 42 TRACK 00 (L) 43 RX3WPTLED (L) (RX50) 44 DRVSL1ACK (L) (RD51) 45 GROUND 46 READ DATA (L) (RX50) 47 GROUND 48 HEAD SEL 0 (L) 49 GROUND 50 READY (L) RD51 disk drive connector pin assignments GND return pin Signal pin Signal name 1 2 Reserved 3 4 Head Select 2 5 6 Write gate 7 8 Seek complete 9 10 Track 0 11 12 Write Fault 13 14 Head select 0 15 16 Reserved (to J2 pin 7) 17 18 Head select 1 19 20 Index 21 22 Ready 23 24 Step 25 26 Drive select 1 27 28 " 2 29 30 " 3 31 32 " 4 33 34 Direction In RD51 disk drive J2 signal Connector pin assignments GND return pin Signal pin Signal name 2 1 Drive selected 4 3 Reserved 6 5 " 8 7 " (to J1 pin 16) 9,10 Reserved 12 11 GND 13 +MFM write data 14 -MFM write data 16 15 GND 17 +MFM read data 18 -MFM read data 20 19 GND Table C3. RD51 disk drive J3 Power connector pin assignments GND return pin Signal pin Signal name 2 1 +12 V 3 4 +5 V From: Steve Mitchell I can't help a whole lot with the pin-out for the RD interface, except to say that they're standard MFM ST-506 interfaced drives. In fact, the RD51 _IS_ an ST-506 drive. You should be able to get the actual pin-outs from PClone hardware books. The 20 pin cable is the data cable, which runs direct from the controller to the drive (star topology). The 34 pin cable is the control cable, which is usually daisy-chained to all the drives attached to a given controller. In both cases, most designers just use straight ribbon cables. For the RX-50 cable, I may be a little more help. My (limited) understanding is that the RX-50 drive interface is the standard floppy drive interface. If that is the case, referring back to the documentation for my ancient Heathkit H-89 computer (back in the days when when men were men and you got schematics for almost everything) we find: all odd pins ground 2 not connected 4 not connected 6 Drive select 0 (or 4 on some drives) 8 INDEXN 10 Drive select 1 12 Drive select 2 14 Drive select 3 16 MOTOR 18 DIR 20 STEP 22 CWD (Write data) 24 WG (Write gate) 26 TK0N (Track 0) 28 WPN (write protect) 30 RRN (Read data) 32 SIDEN 34 not connected Multiple floppies are daisy-chained on the same 34 pin cable. Like the hard drive cables, almost everyone uses straight ribbon cables between the controller and the drives. The only exception to this is IBM and the PClones, which for the floppy cable (and the hard drive control cable in many cases) use a ribbon with just a few lines of the ribbon twisted at the connector in the middle of the cable. This is used to force the drive selection (end of cable is Drive0, middle connector is Drive1). This of course means you DO NOT use the Drive Select jumpers/switches on the floppies on one of these perverse, twisted cables. sigh.