acme/ACME_Lib/cbm/c64/cia1.a
marcobaye 9f4817951a clarified CIA info
git-svn-id: https://svn.code.sf.net/p/acme-crossass/code-0/trunk@320 4df02467-bbd4-4a76-a152-e7ce94205b78
2021-08-11 16:55:40 +00:00

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;ACME 0.96.4
!ifdef lib_cbm_c64_cia1_a !eof
lib_cbm_c64_cia1_a = 1
!source <cbm/cia.a> ; chip stuff (same for both cias)
; stuff for cia 1 only:
!addr cia1_base = $dc00
; both port A and port B are connected to the keyboard matrix.
; in addition to that, they are used for:
cia1_pra = cia1_base + cia_port_a
; %7....... writing 0 selects paddles at port 1
; %.6...... writing 0 selects paddles at port 2
; %...4.... reading 0 means JOY2_BUTTON
; %....3... reading 0 means JOY2_RIGHT
; %.....2.. reading 0 means JOY2_LEFT
; %......1. reading 0 means JOY2_DOWN
; %.......0 reading 0 means JOY2_UP
; kernal's keyboard scanner writes values where a single bit is cleared, going from lsb to msb.
; so most of the time, the last value written will be $7f.
cia1_prb = cia1_base + cia_port_b
; %...4.... reading 0 means JOY1_BUTTON
; %....3... reading 0 means JOY1_RIGHT
; %.....2.. reading 0 means JOY1_LEFT
; %......1. reading 0 means JOY1_DOWN
; %.......0 reading 0 means JOY1_UP
cia1_ddra = cia1_base + cia_data_direction_a ; kernal writes $ff to set to output for keyboard scanner
cia1_ddrb = cia1_base + cia_data_direction_b ; kernal writes $00 to set to input for keyboard scanner
cia1_ta_lo = cia1_base + cia_timer_a_low
cia1_ta_hi = cia1_base + cia_timer_a_high
cia1_tb_lo = cia1_base + cia_timer_b_low
cia1_tb_hi = cia1_base + cia_timer_b_high
cia1_tod10ths = cia1_base + cia_timeofday_10ths
cia1_todsec = cia1_base + cia_timeofday_seconds
cia1_todmin = cia1_base + cia_timeofday_minutes
cia1_todhr = cia1_base + cia_timeofday_hours
cia1_sdr = cia1_base + cia_serial_data
cia1_icr = cia1_base + cia_interrupt_control
cia1_cra = cia1_base + cia_control_a
cia1_crb = cia1_base + cia_control_b
; the interrupt output is connected to CPU's /IRQ input
; in the C128, the shift register is used for the fast serial port (burst mode)