Subject: Re: [stella] Paddle controller docs? From: "Eric Ball" <ericball@xxxxxxxxxxxx> Date: Tue, 17 May 2005 22:49:03 -0400 |
I recently did some proof-of-concept code for paddles on the 7800 (which uses a normal TIA to interface with the paddles), so it's fairly fresh in my mind. From: "C. Bond" > 1) Is there a schematic of the electrical circuit for the > paddles, including component values? Check the schematics on AtariAge (under 2600 archives). > 2) What is the approximate minimum and maximum delay times > from the start of charge to the activation of INPT0? (or > INPT1, INPT2, etc.) minimum is instant, maximum is more than 1/60th of a second (probably more than 1/50th), but I don't think it's much more. > 3) What is the best way to interrogate the paddles? discarge the cap during VSYNC, clamp it near the start of your kernel, count scan lines in the kernel kernel code kinda like this STA WSYNC ; synchronize to start of line LDA INPT0 BIT INPT1 BMI DLIP1 INC OUTP1 DLIP1 ASL BCS DLIP0 INC OUTP0 DLIP0 LDA DLI_A ; restore A register Although this is from a 7800 where cycle counting isn't necessary since you can't update registers while the screen is being drawn. 2600 code should implement standard equal path tricks. Note: you don't have to sample INPTx every line, that just gives you the greatest resolution. A 2LK could sample every other line and get 120 positions instead of 240. Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://stella.biglist.com
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