Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!aramis.rutgers.edu!paul.rutgers.edu!jac From: jac@paul.rutgers.edu (Jonathan A. Chandross) Newsgroups: comp.sys.m68k Subject: Re: 680X0 dream machine Message-ID: Date: 15 Apr 90 00:25:07 GMT References: <105@motto.UUCP> <19620@boulder.Colorado.EDU> <1990Apr12.233111.3455@csuchico.edu> <19699@boulder.Colorado.EDU> Distribution: usa Organization: Rutgers Univ., New Brunswick, N.J. Lines: 37 rainer@hibachi.colorado.edu (Rainer Malzbender) > Secondly, the S100 is not a 32-bit bus. Both Cromenco and CompuPro sell 68020 based systems that use the S-100 bus. Cromenco used two of the reserved pins to implement special 32 bit memory signals. During phase 0 of a bus cycle you request a 32-bit access with one of the wires. During phase 1 you get back 16 bits and the MUACK if the board can deliver 16 bits in the next cycle. During phase 2 you get the next 16 bits. Thus, you can get 32 bits over a 16 bus using 2 of the 3 bus cycles. (I may have butchered the explanation; this is from memory.) I don't know how Macrotech's 386 board deals with things. > Thirdly, it uses cards with on-board regulators, requiring an 8 volt supply > whereas we can buy PC-style +5,+-12 supplies more cheaply. There is now a standard for using regulated supplies; CompuPro and Cromenco use it. The standard basically says that you have to supply jumpers so the board can be used in an unregulated system and that all boards modified to work in regulated systems have to be labelled as such. > Fourthly, my > experience with S100 goes back to the late seventies, so I don't know what > kinds of boards are still being made, but I doubt you'd find anything > all that useful for this kind of project. You would be surprised -- you can get a SCSI board with a time of day clock, and four 38k serial ports (might be 19.2k) for 300-400 bucks from a number of companies. CompuPro, Cromenco, and Macrotech still sell quality high performance stuff. Both CompuPro & Cromenco sell 68020 systems, Macrotech sells a 386 board, you can get a PC compatable video board (will run flight simulator), SemiDisk sells 2 Megabyte solid state disk emulators, etc. The stuff is definitely not cheap, though. Jonathan A. Chandross Internet: jac@paul.rutgers.edu UUCP: rutgers!paul.rutgers.edu!jac