A83: Re: fwd: re: TI-83 port 2
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A83: Re: fwd: re: TI-83 port 2
Could you explain this more precisely ? I mean, which bits do what ?
I think these ports works this way :
Port 3 R/W
R : bit 0 : [on] key pressed
R : bit 1 : periodic interrupt occured ( called VBI by Dines )
R : bit 2 : 2nd interrupt occured ( what does it does ? batteries are checked
when it occurs )
R : bit 3 : Status : bit 0 xor bit 1 xor bit 2 ???
W : bit 0 : [on] int mask
W : bit 1 : periodic int mask
W : bit 2 : 2nd interrupt int mask
W : bit 3 : LCD standby when reset.
I think int are enable when mask =1. After a int has occured, you must reset the
mask, and set it again, right ?
Port 4 W ???R???
W : bit 0 : ???? (freezes calc when set, but used...)
W : bit 1 : ????
W : bits 2 & 3 : select interrupt speed ( $11 : normal, $00 fastest )
W : bits 4..7 : select battery check threshold ???
Port 14 : R ???W???
R : bit 0 : battery state (Good/fair). See threshold
Could you tell me if I'm right, or what they're used for ? And what is the other
int used for ?
I've also got some troubles with port 0 : what are bits 0 1 5 6 7(in read) and 2
3 5 6 7(in write) used for ?
And with port 2 : bits 3 4 5 6 7 ?
And, the ports access only uses bits 4 2 1 0, so port $18= port $10, port
$29=port 1 ?
I know, I ask a lot, but it would really help to understand the ti83 hardware
more precisely... for better emulators, and for better games
- Florent
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Original text
From: Pat Milheron <pmilheron@ti.com>, on 6/17/98 11:06 AM:
To: lairfight@softhome.net
Port 3 is the interrupt status port.
Port 4 is the system configuration port, configures the asic.
Port 14h is used for low battery detection.
Later,
Pat
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