if AEC is tied to VCC I wonder if it is possible to "plug" a 6502 and force P0..P3 to access only the main page and test the machine (obvisouly a custom rom would be needed to test the functionalities) it's useless to try to buy expensive stuff if the board is totally broken... Le 21/02/2018 à 16:15, Mia Magnusson a écrit : > Den Wed, 21 Feb 2018 10:52:24 +0100 skrev didier derny > <didier@aida.org>: >> for the 6509 I guess it's not so simple... the data has to be >> inserted at the right time and aec is missing on the 6502 > Fortunitely, according to all the schematics I've looked at (P500, low > profile and high profile B's, at Zimmers mirror of the defunct funet.fi > site) the AEC is not used but tied to VCC using a resistor. > > I don't know of any other 6509 based computers, so maybe the AEC were > never used. > > The coprocessor slot of the B series uses separate muxes. 4-to-1 muxes > is used for the DRAM adress buss whith one input for the refresh > counter, two inputs for row/column in 6509 mode, and the fourth input > comes from the coprocessor connector. It's a bit strange that the > coprossesor only can access dram directly while everything in page 15 > (I/O e.t.c.) is always connected to the 6509 and a hack using two > 6526's connected to each CPU is used to communicate betweeen the 6509 > and 8088. That could probably had been made nicer, but somehow it > works. It's interesting that the B refresh circuits is used also in > 8088 mode even though the ras/cas muxing is done separately on the 8088 > board in 8088 mode. > >> for the 6525 I was thinking to use a GODIL, >> http://www.oho-elektronik.de/index.php?c=1&s=index >> >> I tried to replace a 6530 a few years ago, but the GODIL I was using >> was broken >> >> I was testing on a kim but I had to give back the kim board before >> the working godil arrived >> >> the main problem with the GODIL: it is huge !!! and with all these >> pins a lot of risks for a short circuit >> >> >> there is also a product made by enterpoint, the craignel >> https://www.enterpoint.co.uk/shop/home/48-craignell1.html >> >> it's really expensive... and the options for he vcc/gnd pins are >> really limited > Back in the days there were a version of the Intel 8048 series that > acts like a peripherial. But I think it has too few pins and also it > uses Intel instead of 6800/6502 bus handshake. > > Anyways it seems unnecessary to emulate all of an 6525 as the two first > ports seems similar to the common 6821 or maybe the rather common 6522. > > >> the cbm II is really new for me, I only saw them once at the Cebit >> 1982 > About the same here, might have seen one at some fair back in 1983, but > have been reading about them now and then in recent years. But they are > so rare and seem so expensive that a replica might seem like a good > hardware project. :) > > I know that I'm the kind of person who overthinks things and feature > creeps everything until it's not feasable, but I think some kind of > "universal-ish Commodore 8-bit board" would be nice. > > Here in Sweden a guy who produce small add-ons for vintage computers > (for profit) is doing a thing that can emulate CBM keyboards. Something > similar would probably be necessary as PET, CBM-II/B, VIC20/C64 uses > different electrical keyboard layouts. > >> I have a new world to discover :) > +1 > Message was sent through the cbm-hackers mailing listReceived on 2018-02-22 10:00:14
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