Among the many expansion cartridges produced for the Commodore 64 and 128, IEEE-488 (GPIB) interfaces are some of the most rare. Designed to bridge Commodore’s hugely popular home computers with the professional-grade parallel bus used by PET machines and instruments, these cartridges occupied a niche market even in the early 1980s.

One of the more rare examples is the BrainBoxes GPIB cartridge. I found it one one of the websites with a lot of unrecognized stuff as HP computer cartridge 🙂 .Documentation is extremely scarce: most references found online describe a bit different BrainBoxes IEEE-488 product that uses a cartridge-like adapter connected to an external IEEE-488 interface. This board, however, is almost certainly the same design internally—just integrated directly into a single cartridge form factor.

One of the ideas will be a full recreation in KiCad, preserving this rare hardware in an open, reproducible form. Hoping to release everything on Githab soon.

Why IEEE-488 on a C64 or C128?

IEEE-488 (also known as GPIB) was widely used on Commodore PET computers and peripherals such as the 2031 series floppy drives. Later Commodore 8-bit machines switched to the slower IEC serial bus, making IEEE-488 peripherals incompatible without an adapter.

For anyone restoring or using PET-era devices – especially disk drives – the ability to connect them directly to a Commodore 64 or 128 is invaluable. This is exactly the problem solved by cartridges like the BrainBoxes GPIB.

Hardware Overview

The BrainBoxes cartridge is a straightforward but elegant design. What immediately stands out is how closely it mirrors the architecture of later IEEE-488 adapters, such as the IEC64 –with one major difference.

Core Chipset

The chipset is almost the same as on the IEC64, but instead of driving the IEEE-488 bus directly via a PIA, the BrainBoxes cartridge uses classic 75xxx IEEE-488 transceiver ICs:

• SN75160 – IEEE-488 talker/listener bus transceiver
• SN75161 – IEEE-488 controller transceiver
• ROM (EPROM) – Contains the cartridge firmware
• 74-series logic ICs – Address decoding, control logic, and signal conditioning
• Passive components – Pull-ups, termination, and basic signal stability

This approach is much closer to traditional IEEE-488 interface designs and aligns well with how Commodore implemented GPIB in PET machines and drives.

Notice the switch for Commodore 64 and Commodore 128 ! 🙂

Design Philosophy

Using SN7516x series drivers offloads the electrical and timing requirements of the IEEE-488 bus from the CPU, making the cartridge robust and electrically compliant. While this increases chip count compared to a PIA-based solution, it results in a very “correct” GPIB implementation.

Unfortunately, SN7416X are now very rare. 5 years ago I tried to assemble PetSD device

Relationship to the IEC64 / IEC64W

If you’re interested in this topic, there is an excellent and very well-written article worth reading:

https://retrorepairsandrefurbs.com/2022/06/27/iec64w-ieee-488-parallel-interface-adapters-for-the-commodore-64-128/

That article documents the IEC64W, an adapter distributed by several German companies and since reverse-engineered and released as open hardware. While the IEC64W uses a 6821 PIA to drive the bus directly, the BrainBoxes cartridge achieves the same goal using dedicated IEEE-488 transceiver ICs instead.

Functionally, both devices solve the same problem:

• Allowing PET-style IEEE-488 peripherals
• To be used on Commodore 64 and 128 systems
• Via the cartridge port, with minimal user intervention

From an engineering standpoint, the BrainBoxes design feels more “old-school GPIB,” while the IEC64W reflects a later trend toward higher integration.

Why This Cartridge Matters

The BrainBoxes GPIB cartridge is a reminder that the Commodore ecosystem was far broader than most people realize. It bridges the gap between home computing and laboratory-grade instrumentation, and it shows how third-party vendors adapted professional standards for consumer hardware.

By preserving the ROM and recreating the PCB, this cartridge can move from obscurity back into practical use -exactly where it belongs.

If you’re restoring a Commodore 2031-LP, experimenting with IEEE-488 instruments, or simply fascinated by rare expansion hardware, the BrainBoxes GPIB is a small but significant piece of retro-computing history.

Yours,

PHOL-LABS CEO

Thanks to Matze’s Galdurino (https://gitlab.com/MHeinrichs/galdurino) project I was able to dump one of GAL16V8 ICs in Macrosystem Vlab video digitizer

Before that, I connected it to my Amiga 2000 and used it to dump the picture from “composite” from A2000.

It worked OK with PiStorm(see picture)

Here you can check Zorro II id’s of VLab:

I was able to dump Lattice GAL16V8 by applying 17V on pin 2, however STs GAL16V8S were not able to be dumped. There were other boards with the same chips by Lattice. I’ll try to take one.

And here is a dump:

I bought this device on eBay and decided to make a replica of it.

An internal genlock for the Amiga which plugs into the video slot (OCS/ECS style). This genlock appears to have been developed for use with the A2000 clone called the Sneak Prevue, a system for broadcasting programming information. The genlock was used to supply video from the Laser Disc Player. (https://bigbookofamigahardware.com/bboah/Product.aspx?id=440)

I bought this device on eBay and decided to make a replica of it. I did not found any other open source genlocks for Amiga so it would be nice to have something in this niche. 

First of all, WARNINGS:

1) The project is completely untested. I plugged in the original card, but it is not a correct test. This project may not work at all, because there are many copper traces. 

2) UVGEN Genlock works on A2000 NTSC machines only, you need to modify circuit for PAL(and I am not sure it is possible to do that)

3) FPGA onboard has its own ROM and it was dumped. EEPROM dump is provided only for home and non-commercial usage. If you want to sell this – write your own ROM for XC2018. 

4) Of course, I am not responsible for any loss, damage, or other things caused by this project to your expensive Amiga desktop. 

5) If you successfully managed to start up this card – please tell me, if I need to do any changes in the project files. Your help will be much appreciated.

6) Inductor values should be inspired from the datasheet

UVGEN genlock consists of video overlay IC MC1378P. See its datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/download/168761/MOTOROLA/MC1378P.html

This IC is controlled by FPGA with OEM ROM which makes all the necessary signals. There are also 4 switches(and thus 16 modes) of Genlock. I do not know how it works. From what I’ve seen on a screen – it chooses signals from Amiga for gen-locking and overlaying. 

HOW IT WAS USED:

– To add Teletext to videos + some effects

– To add captions and credits list

– To make music videos

Original UVGEN Genlock was used for Sneak Prevue TV broadcasting system.

IDEAS ON HOW TO USE IT:

1) Make retro wave videos using composite Amiga video and other video source

2) Make original and 90s-like video clips for music

3) Output composite video from new Amiga 2000s, Amiga 2000 EATX (from jasonbeer, my respect)

I’ll share the original files within several months but first I want some orders to appear from PCBWay to generate some income from my work. Next, I’ll share original schematics and board files too. Please support my work. 

I also plan to make a small SMD-based board with the same functions.

Source and ROMs: