Re: 6510 banking question
Date: 2001-05-04 22:59:19

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

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