Got a Hankering for a Little Swedish Education? Gyorgy Szombathelyi Puts an ABC 80 on Your MIST

Vintage computing enthusiast Gyorgy Szombathelyi has brought a piece of Swedish history back to life, with an FPGA core re-implementation of the Luxor Advanced Basic Computer 80 (ABC 80) for a MIST or compatible board - 46 years after the device was first unveiled.

"ABC 80 (Advanced Basic Computer 80) was a Swedish school/industrial control computer," Szombathelyi explains of the device featured in the latest MIST emulation core. "It has a 3MHz Z80 CPU and graphics capabilities similar to the [Tandy-RadioShack] TRS-80. [It is a] cycle perfect re-implementation based on the original service manual."

The Luxor ABC 80 will likely evoke a sense of nostalgia for Swedish readers, and to Ungarian readers who used Budapesti Rádiótechnikai Gyár's licensed clone — but is probably entirely unfamiliar elsewhere in the world. Based on the Zilog Z80 eight-bit processor, the machine featured Luxor's custom BASIC programming language in a 16kB ROM and up to 32kB of RAM plus dedicated video memory, the latter used to drive a 40-column monochrome text mode or 78×72-block graphics mode on the bundled 12" CRT monitor.

While finding a working ABC 80 today is a trifle difficult — particularly outside the device's native Sweden — anyone with a MIST-compatible FPGA board can now emulate one, thanks to Szombathelyi's open-source core. In addition to cycle-perfect emulation, the core includes the original 16kB ROM, the user's choice of 16kB or 32kB of RAM, support for loading programs from BAC files or real tapes, and "mostly working" emulation of the machine's Texas Instruments SN76477N sound chip.

The core is available to download now from the project's GitHub repository, where the source code is published under the reciprocal GNU General Public License 2.

Main article image courtesy of Ellinor Algin, CC BY 4.0.