CompuServe Messages

We did not have too much success when we first tried to combine a 68030 accelerator with the AT bridgeboard. While analyzing our difficulty, it occurred to somebody that the bb used dual-port memory to pass data between the PC and the Amiga sides of the machine. Without intervention, it would be possible for the 68030 to cache internally data that might be changed by the 80286 in a subsequent operation. Since the 68030 would have no way to know that the data had been changed (it thinks only *IT* can change the contents of memory), the next time data is read from the dual-port ram it may well come from the unaltered cache, not from the altered ram. In reality, the cache is updated from various other data areas (from multiple processes) so much that misreads are infrequent. I worried mostly about the values that were used for handshaking, which might be looked at several times in succession. Cachecard solves this problem by disabling 68030 caching when referencing memory belonging to certain cards. By specifying the AT bridge, you can stop the dual-port memory from being cached. We run our bb off of the Amiga-side hard drive using PCDisk. What I meant by "AT harddrive" is that the GVP 030 accelerator card has an "AT" disk interface, not SCSI. Therefore, by buying a hard drive with an "AT" type interface, you could attach it to the accelerator instead of a separate SCSI card, thus saving a slot. Yes, all of our machines are attached to each other through the Ameristar Ethernet interface. We run TCP/IP, and have our own primitive file/data transfer mechanism hooked up as a development net.