Tandy 1400FD Pinouts

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Pinouts for the internal and external connectors in the Tandy 1400FD are given here. For PSU pintouts, see Tandy 1400FD PSUs.


RS-232 Serial DB-9

1.  Carrier Detect              6.   Data Set Ready
2.  Received Data               7.   Request To Send
3.  Transmitted Data            8.   Clear To Send
4.  Data Terminal Ready         9.   Ring Indicate
5.  Signal Ground


Printer Interface

Pin #   Description   Contents

  1       OUTPUT       STROBE     STROBE signal
  2       OUTPUT       PDB 0      Print data bit 0
  3       OUTPUT       PDB 1      Print data bit 1
  4       OUTPUT       PDB 2      Print data bit 2
  5       OUTPUT       PDB 3      Print data bit 3
  6       OUTPUT       PDB 4      Print data bit 4
  7       OUTPUT       PDB 5      Print data bit 5
  8       OUTPUT       PDB 6      Print data bit 6
  9       OUTPUT       PDB 7      Print data bit 7
                       ____
 10       INPUT        ACKG       Printer Acknowledge
 11       INPUT        BUSY       Printer Busy
 12       INPUT        PAPER END  Out of paper
 13       INPUT        SELECT     Printer select
                       ___
 14       OUTPUT       ATF        Auto feed
                       _____
 15       INPUT        ERROR      Printer error
                       ______
 16       OUTPUT       INIPRN     Initialize Printer
                       ______
 17       OUTPUT       SELINP     Select input
18-25     GND


External 5-inch FDD

Pin #  Contents:                Pin #    Contents

  1      NC                       15      DSEXT*
  2      NC                      16-23    NC
 3-7     GND                      24      INDEX*      
  8      BSIDESE                  25      TRK0*
  9      CDIR                     26      STEP*      
 10      WRPRT                    27      BMTRON*
 11      RDDATE                  28-32    GND
 12      WRTATA                  33-37    NC         
 13      WEN*                    
 14      NC


Modem I/F Slot 20-Pin Socket

Pin #  Signal Name               Pin #  Signal Name

  1      TXDM                      11      GND
  2      RXDM                      12      +5V
  3      DTRM                      13      GND
  4      DSRM                      14      +5V
  5      CDM                       15      GND
  6      RIM                       16      +12V
  7      MODEM PWC                 17      GND
  8      NC                        18      -12V
  9      AUDIO                     19      NC
 10      DIRECT/ACOUSTIC           20      NC


Expansion Box I/F Slot 60-Pin Socket

Pinout

Pin #  Signal Name               Pin #  Signal Name

  1      NC                        31      A19
  2      +5V                       32      D0
  3      /ENABLE (note)            33      D1
  4      NC                        34      D2
  5      NC                        35      D3
  6      /DACK0                    36      GND
  7      IRQ3                      37      D4
  8      NC                        38      D5
  9      GND                       39      D6
 10      A0                        40      D7
 11      A1                        41      /EMW
 12      A2                        42      /EMR
 13      A3                        43      GND
 14      A4                        44      /EIW
 15      A5                        45      /EIR
 16      A6                        46      /TC (note)
 17      A7                        47      ALE
 18      GND                       48      /BRST
 19      A8                        49      /DACK1
 20      A9                        50      IRQ2
 21      A10                       51      GND
 22      A11                       52      +5V
 23      A12                       53      ECLK
 24      A13                       54      IRQ5
 25      A14                       55      DR3
 26      A15                       56      /DACK3
 27      GND                       57      BEN
 28      A16                       58      DR1
 29      A17                       59      IOREADY (note)
 30      A18                       60      GND (note)

Pinouts listed are from the 1400LT service manual; note that surving 1400FD documentation from radioshack.com has a number of differences:

  • ENABLE and TC are listed as active-high
  • AEN (pin 57, BEN) and IOREADY are listed as active-low
  • Pin 60 is listed as MOTOR-ON

However it should be noted that the information in the 1400LT table is more consistent with the ISA bus standard, and that the 1400FD document lists pin 17 as "47", suggesting data may be inaccurate perhaps due to OCR error(s).

Signal Descriptions

Signal Name I/O Description
ECLK 0 Clock: This is the system clock. It has 2 speed modes. (4.77MHz, 7.16MHz). The clock has a 50% duty cycle
/BRST 0 RESET: This is a the system reset. This signal is synchronized to the falling edge of clock and is active LOW
A0 - A19 0 Address Bits 0-19: These lines are generated by either the CPU (V20) or the DMA controller (82C37). They are active HIGH.
D0 - D7 0 Data Bits 0-7: These lines are active HIGH.
ALE 0 Address Latch Enable: This is provided by the Bus Controller (pPD71088). The CPU addresses are latched with the falling edge of ALE.
IOREDY 0 I/O Channel Ready: This line is pulled low by a memory or 1/0 device to lengthen 1/0 or memory cycle.
IRQ 2,3,5 I Interrupt Requests 2,3,5: These lines are used to signal the processor that an I/O device requires attention.
/EIR 0 I/O Read Strobe: This signal is active LOW.
/EIW 0 1/0 Write Strobe: This signal is active LOW.
/EMR 0 Memory Read Strobe: This signal is active LOW.
/EMW 0 Memory Write Strobe: This signal is active LOW.
DR 1 & 3 I DMA Requests 1 and 3: These lines are asynchronous channel requests used by peripheral devices to gain DMA service. A request is generated by bringing DRl and, 3 lines must be held high until the corresponding DACK line goes active.
/DACK 0, 1 & 3 0 DMA Acknowledge 0, 1 & 3: These lines are used to acknowledge DMA requests and refresh system DRAM (DACKO). They are active LOW.
BEN 0 Address Enable: This line is used to degate the CPU and other devices from the 1/0 channel to allow DMA transfers to take place. This signal is active HIGH. When this line is HIGH, the DMA Controller (82C37) has control of the lines (address bus, data bus read and write strobe: memory and I/O)
/TC 0 Terminal Count: This line provides a pulse when the terminal count for DMA channel is reached. This signal is active LOW.
/ENABLE 0 ENABLE: This line maintains a High level when internal devices are selected (ROM. RAM, VRAM, and I/O)
+5v +5V +1%, -5% Max 200mA available on the bus.
GND Power Return for +5V

Hard Disk Controller I/F Slot 60-Pin Socket

Pin #    Signal Name              Pin #  Signal Name

  1      POWER FALL                31      A19
  2      +5V                       32      D0
  3      NC                        33      D1
  4      +12V                      34      D2
  5      +12V                      35      D3
  6      NC                        36      GND
  7      NC                        37      D4
  8      SHIP READY                38      D5
  9      GND                       39      D6
 10      A0                        40      D7
 11      A1                        41      NC
 12      A2                        42      /EMR
 13      A3                        43      GND
 14      A4                        44      /EIW
 15      A5                        45      /EIR
 16      A6                        46      NC
 17      A7                        47      NC
 18      GND                       48      /BRST
 19      A8                        49      NC
 20      A9                        50      NC
 21      A10                       51      GND
 22      A11                       52      +5V
 23      A12                       53      NC
 24      A13                       54      IRQ5
 25      A14                       55      DR3
 26      A15                       56      /DACK3
 27      GND                       57      AEN
 28      A16                       58      NC
 29      A17                       59      NC
 30      A18                       60      GND


See Also