breemen@rulcvx.LeidenUniv.nl (E. van Breemen) (06/20/91)
Leiden, The Netherlands, Wed Jun 19 20:07:10 1991 Today we finished our home-build 68020/68881 accelerator board for the Amiga 500. It's a 14.3 MHz synchronous system, the successor of our 68000 14.3 MHz hack. It's also possible to switch back to the old 68000. Lot's of fun for just $125! Everything worked fine (thanks Dave for your advice) the first time we plugged it in. All software that should work with a '020 works 100%. However, we encountered two problems: Problem I SetCPU V1.6 locks up the machine completely. Maybe this is caused when SetCPU executes a MMU instruction. Our board only responds to FPU instructions, because it decodes the FCx lines and A13 through A19. The '020 probably never receives a *DSACKx and will wait forever... Has anyone encountered this problem? Are there official guidelines that solve this kind of problems? Problem II The other problem occurs when booting a Promigos harddisk. This hd starts up, but after a few startup-sequence commands, it crashes (guru 4). Since all other software works great, we suspect the hd-device driver software to cause the problem. The Promigos harddisk is build around a 5527 OMTI controller. We like to know if anyone else out there uses a Promigos harddisk or another OMTI controlled harddisk with a '020 accelerator without problems. All hints are very welcome, please e-mail! Thanks in advance. Greetings, Raymond Hoving en Erwin van Breemen.