From the Gadgetman's shelves:
The Epson PX-4

So, what's this then? Produced in 1985, it looks superficially like the older HX-20, but when you start looking, then there's a few differences.

But why not start digging...

• Processor: Z80
• RAM: 64KB
• ROM: 32KB
• OS: CP/M V2.2
• Screen: 40x8 Character LCD
• POWER:

  4x1.2V 500mA AA sice Ni-cad cells. A 4.8V 90mA Ni-cad cell for memory retention. (built of 4 1/3AA size cells) If the RAMDISK is mounted, an additional 4x1.2V 500mA AA size Ni-cad pack in that one. PSU: 6V 100mA for mains power and battery recharge.

  Please note the movable plastic piece in this compartment. If you remove the battery, then it can be moved back, exposing normal battery connectors.

• Connectors:
  • 'Mini-Jack': BCR (Bar code Reader)
  • 'Mini-jack': SP (Speaker?)
  • 5pins 'PS/2' connector : Cassette interface.
  • 8pins 'PS/2 lookalike' : Serial.
  • 8pins 'PS/2 lookalike' : RS-232.
  • 20pins (2x10) : Printer.
  • 50Pins (2x25) : Expansion bus.
• Expansion:
  • Upper Right corner: 30pins(2x15) for a small printer or other module. Possibly even a RAM or ROM pack.
  • Lefthand side: A RAM Disk can be connected on the expansion bus. Se separate page.
  • B: and C: drives. these are slots for ROM modules beneath the machine.

The mini printer have a 8049 microcontroller and a 2KB ROM. That is NOT usual in these types. They are usually just 'dumb' interfaces that the computer must control by itself. What made the designers decide on stuffing a dedicated processor in the printer? (Not that I'm complaining. :-)