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Does the card have a known SCSI chip like an NCR5380 or is it pure bit-banging the bus?

So, I puzzled out the interface that I thought might be going on. A buddy and I were talking and he pointed me at http://bitsavers.org/pdf/xebec/104524C_S1410Man_Aug83.pdf which I took a look at on a lark. It's a SASI manual for a SASI to MFM adapter. It has an appendix B which has a sample host interface that very nearly matches (or may actually match.. I need to see if the sample Z80 code lines up to the disassembled driver I have... It's not quite bit bang, but very close at first blush). It's not at all anything like the NCR5380 controller.... Nothing that fancy. There's 3 ports. There's read/write data. Some bits to control data vs control transactions in another register which controls the transactions on the bus. And a register to reset/resync everything. All the details are in that S1410 manual, it seems... The last page has a Z80 bus interface circuit that's plausibly similar to the chips that are on the Univation card. I'll see if I can confirm details and use kicad to draw a schematic.

Very interesting. I wouldn't be surprised at all if it was based on the Xebec sample.

It almost certainly is. I have pics of the end of the card by the SCSI/SASI connector and all the chips are on the Xebec sample card. This looks to be similar to sider on apple2ga. But with some twists since Sider 1 had 256 byte sectors (this has 512) and Sider 2 had 512, but with weird byte interleave that isn't the case here (neither in the image I grabbed from the hard drive nor the driver)... So there may be some code that can be adapted... Looks similar to the lux21056 code on the abcbus that might be adapted. the univation device is a subset and only has sasi_status_r, sasi_data_r, sasi_data_w, sasi_sel_w and sasi_rst_w.... Looks like the status bits are wired up a little differently, though... Still, looks manageable.

The Sider interface card is a relabeled Xebec design, so similarities there aren't surprising at all.

Australia


10 to 14


They do not have a hard drive.


See above

Said Rainbow fancier has equipped themselves to image disks and kindly sent me IMD images for 6 off Lotus 1-2-3 release 2.01 disks
1 off WORDSTAR 3.30 with bootable MS-DOS 2.11
1 off Rainbow 100 Diagnostics Disk, version 1.1
A pair of images (A and B) for Learn Rainbow Bin RX50-A Disk, the B disk needs to be in the other drive.

Apparently these should work on "Rainbow A and B (and B+ for that matter)". Images have been tested by writing back to physical media and tested on actual machine. If these are of interest PM me a real email address and I'll send the .zip

Diagnostic disk boots against the 100A ROMs. The Learn Rainbow pair give a "MEMORY NOT AVAILABLE" error.

Wordstar tries to boot MS-DOS then stalls with a "MAIN BOARD - interrupts off" message in inverse video at the top of the boot screen.

Hi exidyboy, I've sent you a pm with an email address.

Thanks for procuring those images!

So I've imaged all the disks I found. Only 9 differ io.sys versions for 5 known MS-DOS versions: 2.01, 2.05, 2.11, 3.10 and 3.10b... I'll upload once I sort it out. And it looks like exidyboy may have stumbled upon someone with a rare hard disk controller....

Ok. There were 10, but one was 8192 spaces which I eliminated as a legit version...

Here's a scan of the "HARD DISK SUBSYSTEMS for the DEC Rainbow Installation Guide" that Suitable Solutions published. It's a lightly rewritten CHS Dual Disk Controller guide, with advice for what to do with Suitable Solutions IDRIVES if you are installing those as well... I have also found a XDRV.SYS on one of my disks, so we have MS-DOS drivers for the dual card (which happened to be in a Rainbow I bought on spec lately, but it didn't come with a driver). I can't find a DISKPART.EXE that is talked about in the manual, however, so I don't know if I can partition it. Nor do I know if the global 1024 cylinder limit applies to multiple drives, or is really per-drive. Something to play with, I guess. HARD DISK SUBSYSTEM. I'll send it to Al to see if he can include it in Bitsavers. I've also uploaded my Univation manual Univation Install for people that are interested. I'm not yet ready to upload the disassembled driver for the latter, though, since there's a couple of details I want to poke into first.