---
title: "Mega ST 4 High: The Workstation"
section: "retro"
tags: "retro"
description: "The high-end Mega ST 4 workstation with MonSTerBoard, ET4000, NetUSBee, Eiffel interface, a modern STPSU and patched TOS 2.06, running Geneva."
layout: base.njk
parent: "/retro/"
---
<h1>Mega ST 4 High: The Workstation</h1>
<div class="detail-content">

<p>Received for free in 2026, this Mega ST 4 was fully rebuilt and is today my primary workstation. It's the most capable machine in the fleet, running Geneva as a real multitasking environment.</p>

<h2>Details</h2>
<p>Serial: A1 05 4009044 · Manufactured May 1990</p>

<h2>Work Performed</h2>
<ul>
<li><strong>Blitter patch</strong>, removed an existing patch and carefully bridged the severed trace with wire, verifying it with a continuity test. The installed blitter (marked S9012 / MM9092V, a National variant from week 12/1990) belongs to an unproblematic batch where the classic Mega ST blitter patch is generally no longer needed.</li>
<li><strong>CPU socket</strong>, soldered in a 68000 socket and checked all connections to the board with a multimeter.</li>
<li><strong>TOS</strong>, removed the onboard TOS from its sockets to avoid conflicts with the external flash TOS on the MonSTerBoard.</li>
<li><strong>Power supply</strong>, replaced with a modern <a href="/retro/stpsu/">STPSU</a> for clean, stable power, which matters especially for the ET4000.</li>
<li><strong>Floppy drive</strong>, the original drive was defective and got swapped with a working unit.</li>
</ul>

<h2>MonSTerBoard</h2>
<p>The <a href="/retro/monsterboard/">MonSTerBoard</a> is plugged onto the 68000 socket, with jumpers set so TOS 2.06 is used from its flash. The TOS 2.06 is patched to skip the memory check, which noticeably speeds up the boot process. KAOS TOS is also installed on the flash, though currently I always run Geneva with <strong>NeoDesk 4.06</strong> under TOS 2.06. No TOS switcher is wired up yet, so the machine is fixed to TOS 2.06 for now. The MonSTerBoard provides up to 8 MB of AltRAM (TT-compatible range, activated via <code>m_altram.prg</code>), an IDE interface for CF/IDE storage, and a flash ROM holding multiple TOS images. I boot from a 1 GB CompactFlash card over IDE, which is noticeably faster than an ACSI drive.</p>

<h2>Peripherals in Use</h2>
<ul>
<li><strong><a href="/retro/et4000-experiment/">ET4000 graphics card</a></strong> in the MegaBus, providing higher resolutions and better display quality with Geneva/NVDI, driving a dedicated monitor.</li>
<li><strong><a href="/retro/netusb/">NetUSBee</a></strong> on the ROM port, giving real internet via STinG and a USB port for FAT16 data exchange with Windows.</li>
<li><strong><a href="/retro/eiffel/">Eiffel interface</a></strong> for a PS/2 keyboard and mouse, a much better typing feel than the original hardware.</li>
<li><strong>Self-built <a href="/retro/atari-vga/">VGA adapter</a></strong>, a short cable to a small box with the VGA connector and mono/color switch, since a standard adapter would block the ET4000's VGA output.</li>
</ul>

<h2>Role</h2>
<p>Workstation machine with multitasking (<a href="https://www.atari-wiki.com/index.php/NeoDesk">NeoDesk</a> 4.06 under Geneva), AltRAM, IDE/CF boot, USB and network connectivity, and high-resolution display. My primary system for programming and productive work.</p>

<h2>Gallery</h2>
<img src="high-1.jpg" alt="The Mega ST 4 High machine" width="640" height="640" loading="lazy">
<p class="caption">The NeoDesk desktop showing 4 MB ST RAM and 8 MB AltRAM from the MonSTerBoard.</p>
<img src="high-2.jpg" alt="Mega ST 4 High internal view" width="640" height="640" loading="lazy">
<p class="caption">The workstation running GEMBench, with the original Atari keyboard and mouse.</p>
<img src="high-3.jpg" alt="Mega ST 4 High detail" width="640" height="853" loading="lazy">
<p class="caption">GEMBench 6.31 results comparing the ST reference to the High machine at 1024x768 with 256 colors.</p>
<img src="high-4.jpg" alt="Mega ST 4 High expansion" width="640" height="480" loading="lazy">
<p class="caption">The complete setup in daylight, showing the GEM desktop on the EIZO FlexScan L365.</p>
<img src="high-5.jpg" alt="Mega ST 4 High close-up" width="640" height="640" loading="lazy">
<p class="caption">Geneva multitasking: qed, Sound Player, World Clock, and Memory usage running side by side.</p>
<img src="high-6.jpg" alt="Mega ST 4 High running" width="640" height="480" loading="lazy">
<p class="caption">A side view of the setup, showing the Cherry PS/2 keyboard, Logitech mouse via the Eiffel adapter, and the floppy drive.</p>
<img src="high-7.jpg" alt="Mega ST 4 High setup" width="640" height="480" loading="lazy">
<p class="caption">Geneva running Vision 3.5a and qed in parallel, with green ambient light behind the EIZO.</p>
<img src="high-8.jpg" alt="Mega ST 4 High board" width="640" height="640" loading="lazy">
<p class="caption">The NeoDesk Applications menu with Geneva Manager, JAnE, and Vision 3.5a, alongside the system spec file.</p>
<img src="high-9.jpg" alt="Mega ST 4 High final" width="640" height="480" loading="lazy">
<p class="caption">The full workstation at night, driven by the MonSTerBoard, ET4000, and TOS 2.06.</p>

</div>