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 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 the cbm II is really new for me, I only saw them once at the Cebit 1982 I have a new world to discover :) Le 20/02/2018 à 23:37, Mia Magnusson a écrit : > Den Tue, 20 Feb 2018 22:17:16 +0100 skrev didier derny > <didier@aida.org>: >> frankly I just bought a cbm 710 board and was thinking to try to make >> adapter >> >> something like 6502 + cpld >> >> in the cpld the code to trap the 2 opcode sta ($addr), y and lda >> ($addr),y using sync >> >> normally one of the registers 0 or 1 I dont remember (execution) is >> always on the bus >> >> the second is inserted temporarily during these instructions... > This seems to be rather straight forward. > >> I'm thinking to a replacement for the 6525... I'm looking for them, >> hard to find :( > Unfortunitely it seems like the CBM-II/B-series uses one of the 6525's > in the mode where it acts as an interrupt controller. Port A and B can > probably be emulated with an 6821 or similar, or even with simple > hardware registers for those signals that's always used as either input > or output. Fortunitely CB isn't used and CA is used as a simple output > used to control something in the video generation hardware. > > I assume that there are no software for theese computers that use every > single feature of the hardware (like demos on C64), so it might be > possible to get away with a partial emulation of a 6525. > > The other 6525, used for keyboard scanning, seems to be used in it's > simple tri port mode, and could probably be emulated by some really > simple hardware. > > A way of cheating would be using some other kind of hardware and patch > the Kernal, but then you could argue that it's not even a Commodore B > series replica at all. > > Btw I had a look at the P500 schematics. Theese parts seems rather > similar. In general I don't understand why it has both 64K DRAM and 1k > SRAM (plus 1K nybble color ram) connected to the VIC-II? It seems like > the 64k DRAM is only available in page 0 while the small SRAM is > available in page 15 too. That would partially make sense if there > were any coprocessors for the P-500, but I've only heard of the 8088 > card for the B series. But it doesn't really make sense even with a > coprocessor as the 64k DRAM for page 0 is hooked up in a different way > than the rest of the dram, making page 0 available to the 6509 (and > VIC-II) even with another processor using ram page 1-3. Maybe they just > had bad luck when they made the design, or they had problems getting > the dram page 0 to be stable and added the 1k sram as a temporary > solution, never fixed? :) > Message was sent through the cbm-hackers mailing listReceived on 2018-02-21 10:01:19
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