rbt@sftig.UUCP (R.Thomas) (10/02/85)
> > > > > Why not drop in 65802's to replace your 6502's? > > The 65802 is the 6502 pin-compatible version of the > 65816, the new 16-bit 6502. The 65816 features 16 > megabyte adressing, user registers that can be expanded > from eight bits to sixteen, a sixteen-bit stack pointer, > a relocatable zero page (now called the direct page), a block > move instruction, and much more. In its emulation mode, > it emulates a 6502 down to the weird invalid addresses > needed to operate the Apple disk II controller; in native > mode, you already know over half the opcodes if you know how to > program a 6502. > > If a 1MHz 6502 can keep up with an 8MHz 68000, what will happen > when somebody builds a machine using a 4 or 5 MHz 65816 -- > which will be exactly four or five times faster, since the > memory access cycle is the same as the clock cycle? (The > standard 65802/65816 part is 4MHz, and it's CMOS). > > For more information, contact the Western Design Center, 2166 > East Brown Road, Mesa, AZ, 602-962-4545 (it is also being > sourced by GTE Microcircuits). > > David Eyes > Mirror Systems, Inc. > > {cca, ihnp4, inmet, mit-eddie, wjh12} ... > ... mirror!prism!david Does anybody know whether you can replace the 65(C)02 in an Apple IIe/+/c with the 65802 without causing serious compatibility problems? If you do, and if it works, what do you get for your efforts? No chance of direct addressability to memory beyond the II's hacked over 64K, of course, but do the 16 bit registers work?, howabout the 'direct' page stuff?, the block move instructions? Does it mess up any of the timing loops (like in the disk driver software, and the paddle reader software)? Or did they preserve the same number of clocks per instruction as the 6502 as a compatibility 'feature'? Interesting, RIck Thomas ihnp4!attunix!rbt
ix469@sdcc6.UUCP (david smith) (10/06/85)
The 65816 is indeed pin-compatible with the 6502 and it may be
possible to "drop" one into an Apple II without major problems,
provided you don't want to address more than 64K. In order to
address the 16 megabytes, Western Design uses the data bus as
address bus for the half CPU cycle that the data bus is not used.
Unfortunately, during the time, the video is busy playing with
things. I believe that the MMU switches the CPU off the data bus
during that time.
==================
David L. Smith
UC Sandy Eggo
{ucbvax, ihnp4}!sdcsvax!sdcc6!ix469
All opinions expressed herein are strictly the products of my
automated posting facility and have no affiliation with myself, my
employers or my cat.ralphw@ius2.cs.cmu.edu.ARPA (Ralph Hyre) (10/17/85)
In article <2230@sdcc6.UUCP> ix469@sdcc6.UUCP (david smith{|ix}) writes: >The 65816 is indeed pin-compatible with the 6502 and it may be >possible to "drop" one into an Apple II without major problems, >provided you don't want to address more than 64K. I thought only the 65802 was pin-compatible. Has anyone actually made this substitution? >In order to address the 16 megabytes, Western Design uses the data >bus as address bus for the half CPU cycle that the data bus is not >used. Unfortunately, during the time, the video is busy playing with >things. Apple // display circuitry should be redone anyway, they should give up on this color in even or odd column stuff. As long as they keep the entry points for text and graphics routines the same, most stuff should run OK. >I believe that the MMU switches the CPU off the data bus during that time. This seems to imply that Apple was thinking about bypassing the MMU at some later point to get at a large bank of memory. Does the recently accounced Apple memory card have a linear-addressing coprocessor port that would allow a 65816 to address more than 64K without bank switching? (The Applied Engineering Ramworks card does, is AE planning to support people putting in 65816's in their machines by putting an extender socket which would connect the data bus to the coprocessor port before it gets to the MMU chip on the //e motherboard?) If all of this is so, will we see 65816-enhanced Apple // come January? (All the sales people tell me is that the next version of the //e will be the same shade of white as the //c and the Unidisk drive.) -- - Ralph Internet: ralphw@c.cs.cmu.edu (cmu-cs-c.arpa) Usenet: ralphw@mit-eddie.uucp Fidonet: Ralph Hyre at Fido #385 Pitt-Bull (or maybe Net 129, node 0) Snail Mail: don't bother -- - Ralph Internet: ralphw@c.cs.cmu.edu (cmu-cs-c.arpa) Usenet: ralphw@mit-eddie.uucp Fidonet: Ralph Hyre at Fido #385 Pitt-Bull (or maybe Net 129, node 0) Snail Mail: don't bother
ix469@sdcc6.UUCP (david smith) (10/22/85)
In article <216@ius2.cs.cmu.edu.ARPA> ralphw@ius2.cs.cmu.edu.ARPA (Ralph Hyre) writes: >In article <2230@sdcc6.UUCP> ix469@sdcc6.UUCP (david smith{|ix}) writes: >>The 65816 is indeed pin-compatible with the 6502 and it may be >>possible to "drop" one into an Apple II without major problems, >>provided you don't want to address more than 64K. > >I thought only the 65802 was pin-compatible. Has anyone >actually made this substitution? > According to my spec sheet, it is indeed pin-compatible. The data bus doubles as the high eight bits of the address bus during the time that a "normal:-)" 6502 wouldn't be using it. >>Unfortunately, during the time, the video is busy playing with >>things. > >Apple // display circuitry should be redone anyway, they should >give up on this color in even or odd column stuff. As long as >they keep the entry points for text and graphics routines the same, >most stuff should run OK. If you redo the video circuitry, you may as well trash your Apple, since all you're using at that point is the keyboard, slots and power supply. I was thinking of putting a 65816 on a board and running it at 4Mhz, or faster if possible and using the 6502 as an i/o processor. I would like to be able to let the 65816 handle the video display, because it's got such neat tricks built in, like move a block of memory, etc, but I can't think of a neat way to do this without slowing it down to 1Mhz. Perhaps a wait state while the 65816 was addressing low memory would do the trick (slowing it to only 2Mhz). The disk drives would have to be handled by the 6502 (it would be preferable, too!). ================== David L. Smith UC Sandy Eggo {ucbvax, ihnp4}!sdcsvax!sdcc6!ix469 All opinions expressed herein are strictly the products of my automated posting facility and have no affiliation with myself, my employers or my cat.
rbt@sftig.UUCP (R.Thomas) (11/04/85)
> I was thinking of putting a 65816 on a board and > running it at 4Mhz, or faster if possible and using the 6502 as an > i/o processor. I would like to be able to let the 65816 handle the > video display, because it's got such neat tricks built in, like move > a block of memory, etc, but I can't think of a neat way to do this without > slowing it down to 1Mhz. Perhaps a wait state while the 65816 was > addressing low memory would do the trick (slowing it to only 2Mhz). > The disk drives would have to be handled by the 6502 (it would be > preferable, too!). > > ================== > David L. Smith How about putting a cache memory on the board too. (about 256K should do the trick, I would think (:-), but seriously, at today's memory prices, why not!?) There are boards available that do just that with a 65C02 running at about 6MHz (They claim a 3 to 1 speedup, anyway) But they use high-speed static ram (about 8K, I think I remember reading) for the cache. And indeed, they do slow down when accessing the video memory and the IO block between C000 and CFFF. Still, why not put a *big* chunk of memory at addresses above (say) 2MB, that can be accessed fast by the 65816 and only make it slow down to access the low order 128K that it shares with the 6502. The logic of putting it above 2Meg is to get it out of the way of things like RAMWorks or Slinkey, if some way can be worked out to allow the 65816 to access that sort of memory directly. (Probably not, probably have to poke soft switches just like everybody else. But it's worth a try! I say.) Does anybody know enough about the IIe MMU chip to say one way or another? I think it has possibilities! Check the latest issue (or maybe the one before) of Call A.P.P.L.E for an article about the speedup card. I'll bet the people who make that card could be talked into bringing out a 65816 version with only a little prodding. (Unfortunately, I forget the name of the people who make the card, and I cant find the article right now. I'll post that info though, when I can find the article.) Rick Thomas ihnp4!attunix!rbt
ix469@sdcc6.UUCP (David L. Smith) (11/06/85)
Just in case anyone's interested...
Latest prices on 65816, single quantity, from Western Design Center:
2Mhz - $95
4Mhz - $104
==================
David L. Smith
UC Sandy Eggo
{ucbvax, ihnp4}!sdcsvax!sdcc6!ix469
"...here was a being to be reckoned with, a being who had hitchhiked
across the galaxy and still knew where his towel was."