Subject: [stella] 6532 spec From: Dan Boris <dan.boris@xxxxxxxx> Date: Mon, 11 Aug 1997 12:22:05 -0400 |
Last week someone asked for some more info on the 6532 RIOT chip. This information comes from a book by Rockwell about thier AIM Microprocessor trainer. RAM Addressing --------------------------------- RS=0 RW=1 to read, RW = 0 to write A0-A6 select RAM address I/O Addressing --------------------------------- RS=1, A2=0 RW=1 to read, RW=0 to write A0 A1 0 0 PA data 1 0 PA data direction (1=Output/0=Input) 0 1 PB data 1 1 PB data direction (1=Output/0=Input) Write Edge-Detection Control --------------------------------- RS=1, A2=1, RW=0, A4=0 A1=1: Enable interrupt from PA7 A1=0: Disable interrupt from PA7 A0=1: Positive edge detect A0=0: Negative edge detect Read and Clear Interrupt Flag --------------------------------- RS=1, RW=1, A2=1, A0=1 Bit 7 = Timer IRQ flag Bit 6 = PA7 IRQ flag Write Count to Interval Timer --------------------------------- RS=1,A4=1,A2=1, RW=0 A0 A1 0 0 Divide by 1 1 0 Divide by 8 0 1 Divide by 64 1 1 Divide by 1024 A3=1 Enable timer interrupt A3=0 Disable timer interrupt This table did not saying anything about reading from the timer but the text of the book does mention it. From experience with the Atari 2600 I think the timer can be read at: RS=1,A4=1,A2=1,RW=1 (Timer start registers) and RS=1,A2=1,A0=1 The only thing I saw in here that could be potentiolly useful is the Interrupt flag register. When the timer reaches zero bit 7 of this register is set to 1 and stays that way until it is read. This seems to be an easy way to tell when the timer has expired, surprised no one (to my knowledge) has used it. Dan Boris -- Archives updated once/day at http://www.biglist.com/lists/stella/archives/ Unsubscribing and other info at http://www.biglist.com/lists/stella/stella.html
Current Thread |
---|
|
<- Previous | Index | Next -> |
---|---|---|
R: [stella] Cubis beta 2, Piero Cavina | Thread | [stella] Generating Random Numbers, Dan Boris |
R: [stella] Cubis beta 2, Piero Cavina | Date | [stella] Generating Random Numbers, Dan Boris |
Month |