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ps2x2pico


Introduction

Via an OTG adapter, you can plug a USB keyboard into the ps2x2pico, then attach the ps2x2pico to the keyboard DIN connector on your IBM 5150/5160/5162/5170 motherboard.

The ps2x2pico is powered from the +5V pin in the keyboard DIN connector of the IBM 5150/5160/5162/5170 motherboard.

You need to build the ps2x2pico yourself because, at DEC24, I could not find anyone advertising as selling built units.  Basically, you contruct the circuit, then put the applicable firmware into it.

The github web page for the ps2x2pico is at here.


Example construction

One that I constructed is shown at here.


Firmware

Firmware needs to be installed into the ps2x2pico.  Which firmware depends on the target class of computer.

Firmware Target  Comment
ps2pico-XT-alt.uf2 PC and XT  Examples:  IBM 5150 (IBM PC),  IBM 5160 (IBM XT).
ps2x2pico.uf2 AT  Examples:  IBM 5162, IBM 5170  (IBM AT).

To install the firmware

Using Windows on modern computer:

1.  IMPORTANT: Ensure that the ps2x2pico is not connected to the vintage motherboard.  See note 1 below.
2.  Obtain the applicable UF2 file from the ps2x2pico web page.  (ps2pico-XT-alt.uf2 file is for PC and XT, ps2x2pico.uf2 file is for AT.)
3.  Hold down the BOOTSEL button on the ps2x2pico, not releasing it at this time.
4.  With the BOOTSEL button still held down, attach the ps2x2pico's USB port to a USB port on the modern computer.  A new drive will appear in Windows Exporer on the modern computer.
5.  Release the BOOTSEL button.
6.  Copy the applicable UF2 file onto that new drive. Very shortly after that, the new drive will disappear.


LED on Pi Pico

Something that I noticed is that the behaviour of the LED varies according to the firmware.

Firmware  LED behaviour
ps2pico-XT-alt.uf2 The LED is lit when the ps2x2pico receives power.
ps2x2pico.uf2 The LED is lit only when a keyboard is attached to the powered ps2x2pico.


Limitation

You cannot simply move the ps2x2pico between an IBM 5150/5160 and an IBM 5170 (IBM AT), and vice versa.  To move between those two types of systems, you need to put different firmware into the ps2x2pico:
• For IBM 5150 and IBM 5160, use firmware 'ps2pico-XT-alt.uf2'.
• For IBM 5162 and IBM 5170, use firmware 'ps2x2pico.uf2'.




Note 1 If the ps2x2pico is accidentally connected to both the vintage and modern computers at the same time, then there will be two lots of +5V entering the ps2x2pico, one from the vintage computer, and the other from the modern computer.  That may damage the ps2x2pico.