rgt@LANL.GOV (Richard Thomsen) (10/28/87)
I sent this before, but did not receive much response. I do not know if it is because no-one is interested, or because no-one saw it. Now that the mailing list has picked up, maybe someone cares. My Rainbow disk drives failed, so instead of replacing them with the normal DEC drives, I bought two Shugart double-sided 96tpi disk drives and wired them into my Rainbow. They worked pretty well, but had some problems when first being turned on (the disk access would fail, but would start the drives spinning. Accessing the disk again while spinning would then work properly. Anyway, I modified the BIOS (Version 2.11) to fix this problem, and then continued to modify it so it would use both sides of the disk. So now I have two normal disk drives, but they do both single and double- sided disks. This involved modifying the BIOS, the Z-80 code, the MS-DOS bootstrap, and the formatter. So I do not have an I-drive, but my two drives will do the same thing, yet are still 100% Rainbow compatible (as well as doing Rainbow double-sided disks at over 800K bytes each). Basically, I just added the double-sided capability to the BIOS, since it would already do Rainbow and IBM 8- and 9-sector single-sided disks. Now mine does all these, as well as the double-sided versions of them. I wrote to DEC and tried to get the BIOS and permission to modify it and to distribute the modifications, since it is DEC copyright code. I never got any response from them at all. If the BIOS is truly in the public domain, then I would be greatly interested in getting permission to distribute changes to the BIOS. Assuming anyone is still interested. On another problem, my color monitor failed. The blue gun seems to have failed, or the drivers for it. I cannot afford to get a new one from DEC, so I have done nothing about it yet. Does anyone have the schematics or any other information that might help me fix the monitor, or at least test it to find out if it is the tube or the drivers? Any help will be greatly appreciated. Richard Thomsen