p_e@obelix.liu.se (P{r Emanuelsson) (01/12/88)
I have a couple of CDC BR3B5 disks I want to talk SASI to. I'm going to whip up something simple, but I want your advice on which controller chip I should go for. The discs complicate the matter by having 19 heads and a bit rate of 6.5 MHz. They want MFM coded data. Replies by e-mail will be summarized in this group. -- "Be sure brain is in gear before engaging mouth." Dept of Comp and Info Science (uunet!mcvax!enea!liuida!obelix!p_e) Univ of Linkoping, Sweden (p_e@obelix.liu.se, p_e@obelix.UUCP)
p_e@obelix.liu.se (P{r Emanuelsson) (01/19/88)
I wrote: >I have a couple of CDC BR3B5 disks I want to talk SASI to. >[...] >which controller chip I should go for? >The discs complicate the matter by having >19 heads and a bit rate of 6.5 MHz. They want MFM coded data. Maybe I was a bit unspecific since I only got one reply (hi Doug! -- uunet doesn't like ames@uucp so no reply from me). Well, the disks don't have a controller but I have full documentation. They're not SMD, but maybe some predecessor. Anyway, I only have Western Digital's Databook and cannot find a suitable controller. WD1010 or 2010 are out, it would be too much problem interfacing them. (The disks don't want no "stepping pulse" for one. They want the cylinder address on a control bus. And the bit rate is too high.) Maybe the WD1050 SMD-controller would work. Of course, it wants a bit rate of 9.677 Mbits/sec and uses NRZ coded data, not MFM. There may be more differences. I don't know how serious they are. I can't seem to find any reference on the feasibility of converting NRZ <=> MFM right now, would it be easy? At least it's got a control bus for communication with the disk. Then I've got to have a host interface. I have no possibility of writing a new device driver, alas, so I must use what's available. What's available is SASI. :-( I would much rather like SCSI, maybe I can build a dedicated processor to take SASI packets, converting and feeding them to an SCSI bus controller? Seems a bit overkill though... Anyway, please answer the following: 1. Do you know of any disk controller chip meeting the following specs: - MFM coded data. - Able to talk to the disk on a "control bus" or whatever (cyl #, etc). - Handles at least 19 heads. - The usual stuff (formatting, error checking, etc...) Even "I think AMD has one..." may be useful, but please elaborate. 2. Where can I get an SASI bus controller chip? Does it exist? 3. Which SCSI bus controller chip would you recommend? -- "Don't think; let the machine do it for you!" -- E. C. Berkeley Dept of Comp and Info Science (uunet!mcvax!enea!liuida!obelix!p_e) Univ of Linkoping, Sweden (p_e@obelix.liu.se, p_e@obelix.UUCP)
dbraun@cadev4.intel.com (Doug Braun ~) (01/20/88)
In article <1405@obelix.liu.se> p_e@obelix.liu.se (P{r Emanuelsson) writes: >I wrote: >2. Where can I get an SASI bus controller chip? > Does it exist? > >3. Which SCSI bus controller chip would you recommend? > I think SASI and SCSI are virtually identical for most purposes. SCSI basically adds fancy things like syncronous transfer, arbitration, more commands, etc., that you probably will not need. I built a SCSI host interface for a custom Z80 system out of latches and gates; it only took about 10 chips or so. If your stuff is supposed to be connected to a PC, a local surplus place has lots of host adapters for $15. These were made by Ampex for a hard disk add-on system. They have no documentation, but I have disassembled the ROM code on them and written a device driver to control a hard disk on my PC. Halted Specialties in Sunnyvale (Call 408 555-1212 for the phone) has the host adapters. If anyone out there has bought one or could use such a thing, let me know and I will post the code for my device driver. Doug Braun Intel Corp CAD 408 496-5939 / decwrl \ | hplabs | -| oliveb |- !intelca!mipos3!cadev4!dbraun | amd | \ qantel /
phil@amdcad.AMD.COM (Phil Ngai) (01/21/88)
In article <1578@mipos3.intel.com> dbraun@cadev4.UUCP (Doug Braun ~) writes: >In article <1405@obelix.liu.se> p_e@obelix.liu.se (P{r Emanuelsson) writes: >>I wrote: > >>2. Where can I get an SASI bus controller chip? >> Does it exist? >> >>3. Which SCSI bus controller chip would you recommend? I am told that a simplistic SCSI controller is basically a parallel port with 48 mA drive. This would include the NCR 5380. Western Digital has a chip which implements much more of the protocol. I think it's the 33C93. (but don't take my word on these numbers. call a salesman.) I am of course biased because we second source both these chips. But better to get some biased info than none at all, right? -- The VT220 keyboard sucks, but the VT320 is usable. DEC finally got it right! Phil Ngai, {ucbvax,decwrl,allegra}!amdcad!phil or phil@amd.com