PCjr Prototype #122

Typical PCjr from above:

[Image: Photo of typical PCjr from above]

Prototype from above:

[Image: Photo of PCjr prototype #122 from above]

This appears to be a rather late prototype, as it's mostly like the final version. The VGA chip (not to be confused with the later VGA graphics standard) is there instead of being a whole other logic board as I heard it was during prototyping.

Here are some of the differences I've noticed:

• The case is smooth plastic instead of textured.

  • It doesn't have an IBM badge on the top.
  • There isn't any metallic spray coating on the inside.
  • The ports on the back don't have letters in the plastic, so the labels have been hand-written in marker.

• The floppy drive is a Qumetrak 142 as in the final version, but it's a revision A and has a couple bodge wires. (The drive in the normal PCjr is revision D.)

  • It doesn't have an IBM logo on the front.
  • The shape of the handle is different.
  • There is a place on the back of the sled for mounting a fan, but no fan is present.

• The power switch is black instead of red (though I've observed black power switches on what I take to be early retail PCjr power supplies).

• The power supply board has a couple bodge wires.

• The layout of the 64 KB memory card is different.

• The modem lacks Novation markings and appears to have an EPROM piggy-backed on one of the other chips.

• The motherboard has a daughter board plugged into the BIOS ROM sockets.

• The character ROM is an EPROM. (The window wasn't covered, so I covered it with tape.)

• There is no IR receiver installed (though it's not required if you're using a keyboard cable).

• There is a sticker on the side that labels it as prototype number #122. Someone also scratched the number into the underside of the lid.

More photos

next page: Chiclet Keyboard with Printed Keycaps

txti