Sony SMC-70 Microcomputer
Introduced in 1982, the Sony SMC-70 is Sony's first 8-bit personal computer.Arguably, it is the first machine to use Sony's 3.5 inch microfloppy drive.
The SMC-70G is the exact same computer, but comes 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 usage.
![[image]](sony_smc70_b.jpg)
My Sony SMC-70 with 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 connectors for:
Notes:
- Many of the DB25 connectors are "keyed" (one pin is blocked).
This was done to so that you can't accidentally insert a cable into the wrong connector. - To boot off the A: floppy, the Auto Start switch must be in the "Disk" position.
What kind of monitor do I need?
Typically, you'd need a Sony monitor with a "CMPTR" (analog RGB) input and the appropriate cable (ie. "RGB MULTI" to "CMPTR"). However, these can be hard to find. 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.
I wonder if there's a way to rig up a composite video cable to the "B/W Multi Out" connector, but I don't have the pin-outs. (If you figure out how to do it, tell me how and I'll put the info up here).
Can I use it without a monitor?
Yes. You can connect a serial terminal to the "RS-232C" connector, then tell CP/M use the serial port for console (STAT CON:=TTY:). Baud rate is set via DIP switch located under the floppy drives. Switch 2 down selects 9600 baud. There's also a handy little blue DCE/DTE plunger switch. Push it in to select "TO TERMINAL" and out to select "TO MODEM".
Where can I get a boot floppy?
SMC-70 CP/M disk
(ImageDisk format)
Includes hardware-specific utilities BACKUP.COM, DIAG.COM and SETUP.COM
What kind of diskettes does it use?
Sony OM-D3320 or equivalent (SSDD 3.5" microfloppy), either manual shutter or auto shutter.
What peripherals are there?
Here's a (possibly incomplete) list:
What's a cache disk?
The SMI-7050 Cache Disk is a 256KB RAM drive.
Think of it as a very fast disk drive, for example to speed up a compile.
It's possible to use more than one, as long as each card 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 an expansion card?
On either side of the floppy drives, locate two large silver screws and loosen them. At the back of the machine, you will see two small brass knobs protruding from the power supply; pull them straight back to extract a pair of "knitting needles" for lack of a better name. Slide the power supply back, away from the rest of the machine to expose the card slots. Insert the card into a slot. Push the power supply forward against the card. Re-insert the knitting needles. Tighten the silver screws.
Can I read and write these floppies on a different machine?
Assuming you have a floppy containing data files you wish to recover, I've successfully used 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 ENDYou'll need to add the definition to 22DISK's database. For instructions on how to do this, refer to the 22DISK documentation.