1,831 games: 1,608 as they are, 212 to fix (209 built and running), 1 not feasible, 10 unsure. 3 fail on the Multidevice
Which of 1,831 Atari ST hard-disk adaptations run from GEMDOS and GEMDRIVE
The 8bitchip.info website lists 1,831 Atari ST games adapted to start from a hard disk. This project started each one from a GEMDOS drive: a folder that the ST sees as drive C:, file by file, with no disk sectors. Two serve it: the Hatari emulator's GEMDOS drive, and the SidecarTridge Multidevice's GEMDRIVE on real machines, where every fix is tried and what fails is reported. Most games run as they are. The others need one of four fixes.
- 1,608as it is: runs from GEMDOS and GEMDRIVE unchanged
- 212fix: runs once one of the four solutions is applied
- 209of them fixed and running
- 1not feasible: would need the game itself rewritten
- 10unsure: the runs did not settle it
Each square is one game. Each row groups the games by how their adaptation reaches its files. Point at a square to see the game; click it to open its row in the catalogue.
Why some do not
Most adaptations open their files through GEMDOS, by name, and both Hatari's GEMDOS drive and the Multidevice's GEMDRIVE serve them. The Gamex launchers with GOS4 or GOS5 work differently. They bring their own GEMDOS, a copy of TOS 1.04's that runs from RAM and reads the disk sector by sector through a hard-disk driver. GEMDOS and GEMDRIVE have neither the driver nor the sectors, so these 204 games, Lemmings among them, stop at the start. They are most of the games to fix. Why Lemmings fails shows it step by step, and Verdicts and solutions gives the counts for every strategy.
Tested twice
Every game ran in Hatari, on an emulated ST and STE. Every fix then runs on real machines, an ST, an STE, a Mega ST and a Mega STE, with the SidecarTridge Multidevice's GEMDRIVE serving the games from a microSD card. Real machines find failures that Hatari does not show: a file that GEMDRIVE locks, memory that GEMDRIVE uses, a floppy drive that a game waits for. Each one is reported in the catalogue and in how the solutions are tested, with its cause once it is known.
The solutions
Four solutions fix the 212 games. Each one changes the Atari side only; the emulator stays as it is. 209 of the 212 games now run from GEMDOS and GEMDRIVE: Hatari's GEMDOS drive and the SidecarTridge Multidevice's GEMDRIVE.
- S1 rebuilds the start program of the GOS games, so that GOS asks GEMDOS or GEMDRIVE for its files by name. 85 of the 87 GOS5 games run (the GOS5 games, built), and 117 of the 117 GOS4 games (the GOS4 games, built).
- S2, S3 and S4 are small fixes for eight games, and 7 of them run (eight games with a small fix).
| solution | games | running | |
|---|---|---|---|
| S1 | GOS reads through GEMDOS and GEMDRIVE | 204 | 202 |
| S2 | a BPB for GEMDOS and GEMDRIVE | 4 | 4 |
| S3 | the fastload bit in the program it starts | 3 | 2 |
| S4 | Rody and Mastico 4's RUNME.TOS in its folder | 1 | 1 |
What each one changes, costs and risks.
The project
It started with one game: the 2011 hard-disk adaptation of Lemmings, which stops at once when it is started from GEMDOS or GEMDRIVE. The first part of the work found out why, rebuilt the launcher from sources that reassemble to the original bytes, and gave every adaptation on the list a verdict. The second part builds the fixes, one group of games at a time, and tests each in Hatari and on the SidecarTridge Multidevice. Still to come: the games whose verdict is unsure, a check with acsi2stm's GemDrive, and a program that applies the fixes to a user's own copies.
The findings, in the order they were made: why Lemmings fails, the launch chain, the disk layer, the file formats, the launcher's signatures, the modes, recognising the modes from the files and the verdicts and solutions.