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Started by David Lounsbury
Tue, 23 Jul 1985 19:34
Address bit 24
Author: David Lounsbury
Date: Tue, 23 Jul 1985 19:34
Date: Tue, 23 Jul 1985 19:34
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Has anyone done a design using address bit 24 from the 32082 MMU? National has some vague suggestions about ICEs, but I'm wondering about using this bit as part of the physical address. Any thoughts or suggestions are appreciated. Thanks in advance. -- David M. Lounsbury usenet: harvard!prime!davel ARPA: davel%prime.UUCP@harvard.ARPA phone: (617) 626-1700 x3030 MCI: DLOUNSBURY ELS: 627 87559 Telex: 650 177 1334 "Just dreames, dopes, and day-to-day data dolts."
Re: Address bit 24
Author: Steve Glaser
Date: Mon, 29 Jul 1985 23:04
Date: Mon, 29 Jul 1985 23:04
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In article <128@prime.UUCP> davel@prime.UUCP (David Lounsbury) writes: > Has anyone done a design using address bit 24 from the 32082 MMU? > National has some vague suggestions about ICEs, but I'm wondering > about using this bit as part of the physical address. Any thoughts > or suggestions are appreciated. It works just like another address bit. I understand that Sequent use it exactly that way. They support 28(?) Mbytes of memory (32M less some I/O space). We use it to enable our address expansion hardware (Tektronix 6200 series workstations) - local memory gets "simple" 24 bit addresses, but the main system bus is 32 bit addresses requiring additional hardware to generate. If you want to go out on the system bus, kick A31 on and you can generate a full 32 bit address. We went with a 32 bit main bus so we don't have to redo things down the road. National data books refer to A31 (aka A24) as "AS" (Address Space) and intended to have it used for selecting emulated memory or real memory when doing In Circuit Emulation. To my knowledge nobody uses it for that purpose (including the National ICE products). Steve Glaser Tektronix Inc.
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