dave@csis.dit.csiro.au (David Campbell) (06/25/91)
How difficult would it be to build a board with a 68020 and an MMU that would drop into the CPU socket replacing the 68000? Ignore the possibility of 32-bit memory, I just want the MMU capabilities. Can somebody please describe the problems I would face? A friend tells me that its necessary to ensure adequate time for interleaved access to the video ram; can anybody enlarge on this and any other problems.. An 030 would probably be easier but also more expensive. Thanks.. Dave Campbell dave@csis.dit.csiro.au -- dave campbell
breemen@rulcvx.LeidenUniv.nl (E. van Breemen) (06/25/91)
In article <1991Jun24.215409.3740@csis.dit.csiro.au> dave@csis.dit.csiro.au (David Campbell) writes: >How difficult would it be to build a board with a 68020 and an MMU that >would drop into the CPU socket replacing the 68000? Ignore the >possibility of 32-bit memory, I just want the MMU capabilities. > >An 030 would probably be easier but also more expensive. > >Thanks.. >Dave Campbell I think you can better buy an 68030 because the MMU is relativly expensive for an 68020. Making an interface is very simple. Just read the docs of Commodore about expansionboards and follow the guidelines. We have made a synchronous 68020 board in 6 weeks and it worked the first time we plugged it in. An 68030 interface will be more or less the same. Things will get a bit more complicated for an asynchronous board.Then you will have to add a datalatch for the databus. This is not neccesary for a synchronous board. hpoing this will help, Erwin van Breemen
lron@easy.lrcd.com (Dwight Hubbard) (06/26/91)
In article <1991Jun24.215409.3740@csis.dit.csiro.au> dave@csis.dit.csiro.au (David Campbell) writes: >How difficult would it be to build a board with a 68020 and an MMU that >would drop into the CPU socket replacing the 68000? Ignore the >possibility of 32-bit memory, I just want the MMU capabilities. > >Can somebody please describe the problems I would face? A friend tells >me that its necessary to ensure adequate time for interleaved access >to the video ram; can anybody enlarge on this and any other problems.. > >An 030 would probably be easier but also more expensive. Well, if price is the determining factor wouldn't a 68010 be cheaper?
rkushner@sycom.UUCP (Ronald Kushner) (06/27/91)
lron@easy.lrcd.com (Dwight Hubbard) writes: >In article <1991Jun24.215409.3740@csis.dit.csiro.au> dave@csis.dit.csiro.au (D >>How difficult would it be to build a board with a 68020 and an MMU that >>would drop into the CPU socket replacing the 68000? Ignore the >>possibility of 32-bit memory, I just want the MMU capabilities. >> >>Can somebody please describe the problems I would face? A friend tells >>me that its necessary to ensure adequate time for interleaved access >>to the video ram; can anybody enlarge on this and any other problems.. >> >>An 030 would probably be easier but also more expensive. > >Well, if price is the determining factor wouldn't a 68010 be cheaper? A 68010 doesn't have the MMU he wants..... Doesn't the A2000 schematics show the 86 pin connector as a MMU slot?? -- C-UseNet V0.42e Ronald Kushner Life in Hell BBS +1 (313) 939-6666 P.O. Box 353 14400 USR HST V.42 & V.42bis Sterling Heights, MI 48311-0353 Complete Amiga Support UUCP: uunet!umich!vela!sycom!rkushner (We are not satanic, just NUTS!) It works better if you plug it in.
lron@easy.lrcd.com (Dwight Hubbard) (06/27/91)
In article <rkushner.3011@sycom.UUCP> rkushner@sycom.UUCP (Ronald Kushner) writes: >lron@easy.lrcd.com (Dwight Hubbard) writes: >>In article <1991Jun24.215409.3740@csis.dit.csiro.au> dave@csis.dit.csiro.au (D >>>How difficult would it be to build a board with a 68020 and an MMU that >>>would drop into the CPU socket replacing the 68000? Ignore the >>>possibility of 32-bit memory, I just want the MMU capabilities. >>> >>>Can somebody please describe the problems I would face? A friend tells >>>me that its necessary to ensure adequate time for interleaved access >>>to the video ram; can anybody enlarge on this and any other problems.. >>> >>>An 030 would probably be easier but also more expensive. >> >>Well, if price is the determining factor wouldn't a 68010 be cheaper? > >A 68010 doesn't have the MMU he wants..... Neither does the 68020, but the 68010 if I remember right differs from the 68000 in that it can handle an MMU while the 68000 can't. >Doesn't the A2000 schematics show the 86 pin connector as a MMU slot?? Something like that, with like one or two signals missing that are available on the motherboard. Of course all the signals needed are at the CPU socket too :-) -- ---------------------------------------------------------------------- -Dwight Hubbard INTERNET: lron@easy.lrcd.com - -Kaneohe, Hawaii USENET : ...!uunet!easy!lron - - BIX : lron - ----------------------------------------------------------------------