Now I Have Agon Light

So, given my interest in retrocomputing, I have bought myself Agon Light computer, AgonLight2 version.

What is it?

It is actually modern “old” computer, having 512 kilobytes of memory and eZ80 CPU. The CPU has two modes:

  • one is fully compatible with classic Z80 CPU (8-bit, 64 kilobytes of addressable RAM)
  • one is slight extension of it (24-bit, and this is not a typo)

There is also ESP chip which handles keyboard, graphics, and audio.

Connections

The board has the following connections:

  • VGA. It did not work with VGA-HDMI adapters I have, so I connected it to old (20 years) VGA monitor, and ordered the adapter which claims to support AgonLight2 – believe or not it is a VGA-HDMI adapter which requires external power source.
  • USB type A for a keyboard, but it should support PS/2 protocol: I have got this one and it works.
  • USB type C for power. Power requirement is not huge, and my computers (including some laptop) give the required power (but see below).
  • Battery connector. AgonLight2 has built-in charging circuit, so if you connect a battery (I have got this one) it will charge itself from USB-C and then can supply power to the board. Olimex’s web site claims it will have enough juice for about 8 hours, but I did not test it yet. I have found no way to check the battery charge level. There is a led on the board which is lit while battery is charging and goes off when it is charged, but I do not see it because I also bought a case. The battery stays outside of the case.
  • GPIO.
  • UEXT.
  • SD-card slot (see below).

Operating system

The board has its own operating system, called MOS. It uses for storage SD-card (class 10, 32 gigabytes maximum). I use class 10 Kodak’s 32 gigabyte SD-card and it works.

My board had a version 1.04 of official AgonLight2 MOS (but see below).

Firmware

The board’s firmware consists of two parts: MOS (operating system, running on eZ80 itself) and VDP (firmware for ESP chip). Official firmware is called “QUARK” (I have linked to MOS above, here is the link to VDP). My board was running VDP 1.04-RC1.

The first thing I did I have updated the firmware to the Console8 version ( MOS and VDP) following community documentation. As my board had relatively recent versions of QUARK’s MOS and VDP, updating was a simple as putting the needed files on SD-card and typing flash all.

Warning: the documentation says that ESP jumper should be closed; my board did not boot if it was closed (the board has arrived with that jumper open). In open state the board booted and I successfully updated VDP.

The Console8 of firmware is fully compatible with AgonLight2 and is recommended by the documentation.

Software

On board I am using Agon Mite 24.04.01 LTS.

I still did not try, but as a cross-assembler I found spasm-ng. To compile it on FreeBSD I have to use GNU make and pass -lcompat to the linker: LD_FLAGS=-lcompat gmake.

Next steps

I have successfully used graphics from Basic. Now I intend to try and write about my experiences with:

  • new VGA-HDMI adapter
  • ez80asm – an assembler, running natively on the board
  • cross-compiling with spasm-ng
  • using MOS from assembly
  • using graphics from assembly
  • cross-compiling with some C compiler
  • sound
  • Agon emulator
  • creating “moslets” – programs, extending MOS
comments powered by Disqus