On 12/08/2011 03:04, Dave Caroline wrote: The last two aren't RQDX1 controllers, they're the RQDX1E extender (M7512), which is a passive card that breaks out signals in order to use drives in a BA23 expansion box. Similar to an RQDXE, but specifically designed for RQDX1. There were three versions of the RQDX1 board. The original, RQDX1 M8369, got a firmware update that made it an M8639-YA, to handle more drive types. The only difference is the firmware, and there were a few versions of that. Then there's an M8639-YB, which is called RQDX2, and which has some ECOs to remove some of the restrictions on bus position (it handles BIAK and BDMG). The RQDX2 firmware versions use slightly different error codes on the LEDs and handle at least one of the drive interface signals differently. Different firmware again (more drive types) but you can mix and match the firmware between boards, including putting RQDX2 firmware in RQDX1 to get more drive support (that was officially supported by DEC). However there are some restrictions. Later firmware changed the structure of the RCT/FCT tables that keep drive config info, and which are written to the drive. If you take a drive formatted on an early version, and put it on a later version, the controller should in most cases cope. Unfortunately going the other way doesn't work in every case, because the later firmwares write slightly larger tables to the drive, and then early firmware doesn't understand it. One of the "RQDX1/2 Survival Tips" on STARS listed the first 6 versions of firmware, and mentions that some firmware will rewrite the tables if you move a drive from old to new. So a drive that used to work on one controller gets moved, still works, but then won't work if moved back. If you have a look at my ROMlist page http://www.dunnington.u-net.com/public/DECROMs/ROMlist you'll find some very brief notes. 23-188E5 23-189E5 M8639-YB RQDX2, issue 2 RD51,RD52,RD53,RX50 support Firmware V10.0E 23-178E5 23-179E5 M8639-YB RQDX2, issue 1 RD51,RD52,RD53,RX50 support Firmware V10.0D 23-172E5 23-173E5 M8639-YA RQDX1, issue 3 RD51,RD52,RX50 support Firmware V9.4E 23-042E5 23-043E5 M8639-YA RQDX1, issue 2 RD51,RD52,RX50 support Firmware V9.0 23-264E4 23-265E4 M8639 RQDX1, issue 1a RD51,RX50 support only Firmware V8.0 23-238E4 23-239E4 M8639 listed as RQDX1 V7.0, but apparently a misprint? those numbers used for KDJ11-BE The different versions of firmware also use different sniffer boots to try to work out what drive is attached. Pain in the proverbial, that was. I have drives that will work and format on one version but not another (later versions are more picky about what they'll recognise as an RD51, for example). I spent quite a while around 1990 playing with firmware and different (non-DEC) drives (HDD and floppy), and I have several versions in my ROM list page. I even exchanged some email with one of the firmware designers, but I can't remember the details -- just that the sniffer boots got more complex as time went on. As an aside, while digging through old notes and archives to check what I wrote, I found Note 93 on EISNER from 1988 that describes how to jumper two RD5x drives in a BA23. Note 526 as well. Two RD31/RD32 was actually a supported config. -- Pete Peter Turnbull Network Manager University of York