Sony SMC-70 Microcomputer

Introduced in 1982, the Sony SMC-70 is Sony's first 8-bit personal computer.
It is arguably the first machine to use Sony's 3.5 inch microfloppy drive.
The SMC-70G is the exact same computer, but with an NTSC video genlocker,
while the SMC-70GP has a PAL video genlocker.
The original target market was CAI (computer assisted instruction) and broadcast video.
The computer itself is a solid CP/M system, well-suited for general purpose use.

  • 4 MHz Z80A CPU
  • 64 KB RAM
  • 3.5" microfloppy drive (capacity 268KB each)
  • 3 expansion card slots
  • CP/M 2.2 (with custom color extensions)

    [Photo]
    My Sony SMC-70 and KX-8200CD monitor at the 2005 Trenton Computer Fest. (Photo by B. Degnan)

    Frequently Asked Questions

    Does it have any I/O ports?

    There are ports for:

  • B/W Multi Out (composite video?)
  • Printer (parallel)
  • Auto-start switch: ROM / Disk / Off
  • RGB Multi Out (analog RGB)

  • Key pad
  • Light pen
  • Tape (cassette)
  • RS-232C (serial)

    Notes:

    Many of the DB25 connectors are keyed (one pin is blocked).
    This was done to prevent you from accidentally plugging a cable into the wrong connector.

    To boot from floppy, the Auto Start switch must be in the "Disk" position.

    What kind of monitor do I need?

    You'll need a monitor with analog RGB input and an appropriate cable. These monitors can be difficult to find. The cables, even more so. Monitors I've used are the Sony KX-1211HG, PVM-1270Q and KX-8200CD. I don't have the model number for any of the cables, sorry.

    There maybe a way to rig up a composite video cable using the "B/W Multi Out" connector, assuming you can find the correct plug. Referring to the pinouts, it looks like pin 8 is signal and 7 is GND.

    Can I use it without a monitor?

    You can connect a serial terminal to the RS-232C port. Baud rate is set via DIP switch located under the floppy drives. For example, switch 2 down selects 9600 baud. There's also a handy little blue DCE/DTE plunger switch; push it in to select "TERMINAL". Finally, boot a CP/M floppy, wait until the floppy access LED goes out, press enter a few times and type
    STAT CON:=TTY:

    Where can I get a boot floppy?

    SMC-70 CP/M boot disk (ImageDisk format)
    Includes hardware-specific utilities BACKUP.COM, DIAG.COM and SETUP.COM

    A: SETUP    COM : BACKUP   COM : SUBMIT   COM : XSUB     COM
    A: STAT     COM : DDT      COM : LOAD     COM : PIP      COM
    A: ED       COM : ASM      COM : DUMP     COM : DUMP     ASM
    A: DIAG     COM : SAMPLE   TXT
    
    Collection of utilities (ImageDisk format)
    Includes Sony Disk BASIC and demo, QTERM, VDE editor and Rogue game
    B: BASIC    COM : DEMO     BAS : NS207    COM : NULU15   COM
    B: QT-DGSMC Z   : QTERM    COM : QTERM    DOC : QTERM    PAT
    B: ROGUE    COM : ROGUE    DOC : ROGUE    NOT : SMC70ESC TXT
    B: UNARC    COM : UNCR     COM : UNCRLZH  COM : UNSQ     COM
    B: VDE      COM
    

    What kind of diskettes does it use?

    Sony OM-D3320 or equivalent (SSDD 3.5" microfloppy), either manual shutter or auto shutter.
    In a pinch, you could probably use DSDD 720K media.

    What about peripherals?

    Here's a (possibly incomplete) list of peripherals:

  • SMI-7011 3.5" floppy drive bay (internal with 1 drive)
  • SMI-7012 3.5" floppy drive bay (internal with 2 drives)
  • SMI-7012A 3.5" floppy drive bay (internal with 2 Auto-Shutter drives)
  • SMI-7013 3.5" floppy drive bay (external with 1 drive)
  • SMI-7014 3.5" floppy drive bay (external with 2 drives)
  • SMI-7016 Floppy Disk Control Unit
  • SMI-7020 Dot Matrix Printer
  • SMI-7031 RS232C Serial Interface
  • SMI-7031A RS232C Serial Interface (programmable)
  • SMI-7032 IEEE-488 Interface Unit
  • SMI-7050 Cache Disk Unit
  • SMI-7056 Supercharger (also SMC-7086)
  • SMI-7060 10-Key Numeric Key Pad
  • SMI-7070 Video Signal Converter
  • SMI-7073 RGB Superimposer
  • SMI-7074 NTSC Superimposer
  • SMI-7075 Videotizer
  • SMI-7080 Battery Back-up Unit

    What's a cache disk?

    The SMI-7050 Cache Disk is a 256KB RAM drive. You'd use it, for example, to speed up a compile. It's possible to use more than one card in the computer, as long as each one is assigned a unique unit code, selected via a rotary switch below an access panel at the back of the card. (Default unit code is 0).

    How do I install or remove expansion cards?

    Locate two large silver screws on either side of the floppy drives and loosen them. At the back of the machine, find the two small brass knobs and pull on them to extract a pair of "knitting needles" (for lack of a better term). Slide the power supply away from the rest of the system to expose the card slots. Remove or insert cards. Push the power supply against the cards, re-insert the needles and tighten the silver screws.

    Can I read and write floppies on a different machine?

    I've successfully used an MSDOS computer with a 3.5" drive, a program called 22DISK and this definition:

    BEGIN SON1  Sony SMC-70 - SSDD 3.5"
    DENSITY MFM, LOW
    CYLINDERS 70 SIDES 1 SECTORS 16,256
    SIDE1 0 1,4,7,10,13,16,3,6,9,12,15,2,5,8,11,14
    BSH 4 BLM 15 EXM 1 DSM 135 DRM 127 AL0 0C0H AL1 0 OFS 2
    END
    
    You'll need to add the definition to 22DISK's database. For instructions on how to do this, refer to the 22DISK documentation.

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