Setting up the HSGPL for MAME

Introduction

The HSGPL is a peripheral expansion expansion card created by the System 99er User Group (SNUG). It contains Flash ROM circuits and RAM circuits, so parts of its memory is persistent. The HSGPL is able to simulate 16 individual cartridges. They can be switched by the console-internal cartridge selection. The intended use is to dump a plugged-in cartridge on disk, and then to upload the data into one of the 16 banks.

In addition, the HSGPL replaces the GROMs in the console. When the card is plugged in, the console GROMs should be removed, or the card will not offer its complete functionality.

This also means that a completely blank HSGPL will not work. In that case, the TI system will immediately lock up with a black screen when turned on. The minimum contents of an HSGPL is a basic DSR and the console GROM contents. Each real HSGPL card is delivered with this minimum content.

The HSGPL emulation

In the TI part of the MESS emulator, the HSGPL card is emulated with the implementation to be found in machine/ti99/hsgpl.c. The complete circuitry is emulated by following the functional description (instead of utilizing the schematics and printed board layout). Since MESS does not provide ROM contents due to copyright restrictions, you have to get an own copy of the HSGPL DSR and initial memory contents. If you own an HSGPL you can dump the contents with your real TI and transfer them to the MESS TI emulation. Otherwise you should get in contact with the SNUG people and request a copy of the DSR.

You can select the HSGPL in the Driver Configuration menu. Locate the setting HSGPL extension and turn it on or off.

Once more, keep in mind:

If you activate the HSGPL extension without the initial ROM contents, the emulation will lock up. This is not an error - it perfectly mirrors the real happenings.