Okay, it sounds like you're confirming what I suspected. PLA controls which devices the 6510 can see in the map (RAML/RAMH/ROML/ROMH/IO/CHARGEN). The user/program CANNOT directly manipulate the PLA. A hardware RESET signal applied to the PLA (technically -RESET, IIRC) forces the banking logic of the PLA into the ROML/ROMH/IO configuration. R6510 is a 6-bit bi-directional I/O port on the 6510 chip. Bits 0-2 of R6510 control the banking inputs of the PLA. -RESET forces the port to input mode and clears the port data to $00 (just like the 6526). Then the pull-up resistors bring the port to output mode (referring to all 6 lines) So, if I'm writing my own KERNAL, I can expect the following conditions after every -RESET: PLA configured to ROML/ROMH/IO D6510 = all outputs R6510 = $00 Hmm ... there seems to be a conflict here ... :-/ --- email@example.com wrote: > Hallo PD, > > > Is the hardware configured to ROML/ROMH/IO by the > > RESET signal or does is depend strictly on IOINIT > to > > configure it that way? > > A RESET puts the onboard port in input mode. Some > resistors pull the lines > (H). During IOINIT the 6510 programs pins as (H) and > as output. AFAIK in > that order. > > > The hardware that controls the banking function is > in > > the PLA right? I.E. R6510 is strictly a > bi-directional > > I/O register and the banking logic is external to > the > > 6510, right? > > Banking is setting a register which on the end > enables a different part of > the memory. So IMHO the 6510 and PLA are both a part > of the banking system. > The PLA is nothing more then a bunch of gates, _NO_ > flipflops, and does > nothing more then a kind of translation: a certain > code on the input lines > leads to a certain code on the outputlines. You > could say that the > 81S100-PLA is nothing more then a very fast ROM. > > Groetjes, Ruud > > http://Ruud.C64.org/ > > > > - > This message was sent through the cbm-hackers > mailing list. > To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org. ===== Get a FREE 6Mb webmail box from go6502! - http://www.geocities.com/profdredd __________________________________________________ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices http://auctions.yahoo.com/ - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail email@example.com.
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