Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!bagate!dsinc!unix.cis.pitt.edu!zaphod.mps.ohio-state.edu!samsung!rex!uflorida!gatech!ncsuvx!news From: kdarling@hobbes.ncsu.edu (Kevin Darling) Newsgroups: comp.os.os9 Subject: Re: TC-70 and MM/1 Message-ID: <1991Jan28.023320.24569@ncsuvx.ncsu.edu> Date: 28 Jan 91 02:33:20 GMT References: <1990Dec28.012907.24001@davidge> <2535@batman.moravian.EDU> <1991Jan27.135517.12380@ncsuvx.ncsu.edu> Sender: news@ncsuvx.ncsu.edu (USENET News System) Distribution: usa Organization: NCSU Computing Center Lines: 37 >halkoD@batman.moravian.EDU (David Halko) writes: >The TC-70 comes with more memory than the MM/1 (from what I last remember...) >Because of the extra memory, the TC-70 is slightly faster than a stock MM/1. Yes. And No. ;-) The VSC chip can handle up to 1.5 meg RAM, of which 1 meg may be video. The TC70 comes with 1.5 meg; the MM/1 with 1 meg. But neither is faster: all RAM accesses goes thru the VSC and are subject to video access sharing. Once you expand the systems (MM/1 on second board, TC70 on K-Bus RAM card), then the cpu can get full-time accesses to that VSC-external RAM, giving about a 50% increase in overall system speed (you jump from being approx equivalent to an 8Mhz 68000, up to about a 12.5Mhz 68000). It might turn out that the MM/1 is faster on expanded systems tho. See, when you add fast external RAM on it, that RAM is set to map in at the lowest 68K addresses _instead_ of the slower VSC RAM (which gets moved elsewhere). This means that all the OS9 kernel code and vectors are loaded into, and run from, fast RAM instead. I dunno what the TC70 does. Anyone? > [...] In general agreement with the rest. The K-Bus provides for a hacker's delight. The MM/1 was designed for plug-and-go inexpensive. I suspect bus adapters for both could become popular. >cocoiii@hobbes.ncsu.edu (John Vestal) writes: >True, but the KBus is a 16-bit bus. The MM/1 has a 32-bit bus. No. The MM/1 has an optional 32-bit bus designed, but the stock commercial version only needs and uses a 16-bit bus. The more important difference is that the MM/1 bus allows multiple bus masters... meaning that assuming a 68030 card becomes available, both it and the 070 could access any peripherals (34010 video, multiple serial port card, etc) on a backplane with more slots. As Jim Omura pointed out tho, what exists now may be more important than conjecture. - kevin