wip: keyboard send

main.s65

@@ -42,10 +42,13 @@ irq:
     ; DEBUG_LED_ON 2
 @irq_io1:
     lda IO1 + IO::IFR
+    and IO1 + IO::IER           ; sometimes CB1/2 IFR set even though not enabled in IER
     sta irq_via_ifr
-    bbr7 irq_via_ifr,@irq_io2  ; skip
+    bbr7 irq_via_ifr,@irq_io2   ; skip
-    bbs2 irq_via_ifr,@irq_kb1  ; shit reg -> first 8 bits
+    bbs2 irq_via_ifr,@irq_kb_sr
-    bbs5 irq_via_ifr,@irq_kb2  ; timer -> last 3 bits
+    bbs3 irq_via_ifr,@irq_kb_cb2
+    bbs4 irq_via_ifr,@irq_kb_cb1  
+    bbs5 irq_via_ifr,@irq_kb_t2  
     bra @irq_unknown
 @irq_io2:
     lda IO2 + IO::IFR
@@ -56,7 +59,6 @@ irq:
 
 @irq_unknown:
     ; this SHOULD never be reached
-    jsr lcd::clear
     Print "Unknown IRQ"
     ; force reset interrupt flags
     lda #$ff
@@ -71,14 +73,15 @@ irq:
     bra @irq_return
     ; jmp (spi_p::irq_handler)
     ; JsrIndirect (spi_p::irq_handler), @irq_return
-@irq_kb1:
+@irq_kb_sr:
     ; Print "$3000"
-    jsr $3000
+    JsrIndirect ($3000), @irq_return
-    bra @irq_return
+@irq_kb_cb2:
-@irq_kb2:
+    JsrIndirect ($3020), @irq_return
-    ; Print "$3100"
+@irq_kb_cb1:
-    jsr $3100
+    JsrIndirect ($3040), @irq_return
-    bra @irq_return
+@irq_kb_t2:
+    JsrIndirect ($3060), @irq_return
 ; @irq_dht:
 ;     lda IO1 + IO::T1CL ;T1L2  ; clear interrupt flag
 ;     bra @irq_return

spicode.s65

@@ -5,6 +5,8 @@
 .include "keypad.h65"
 .include "keyboard_handler.h65"
 .include "chars.h65"
+.include "parity.h65"
+.include "sleep.h65"
 .import homeloop:absolute
 .import home:absolute
 
@@ -25,37 +27,30 @@ CODE_START:
     DEBUG_LED_OFF 1
     DEBUG_LED_OFF 2
 
-    StoreDByte kb_irq1, ARG0
+    StoreDByte _process_cmd_answer, $3200
-    StoreDByte $3000, ARG2
-    ; lda #<kb_irq1
-    ; sta ARG0
-    ; lda #>kb_irq1
-    ; sta ARG1
-    ; lda #<$3000
-    ; sta ARG2
-    ; lda #>$3000
-    ; sta ARG3
-    ldy #10
-    jsr memcopy
-
-    StoreDByte kb_irq2, ARG0
-    StoreDByte $3100, ARG2
-    ; lda #<kb_irq2
-    ; sta ARG0
-    ; lda #>kb_irq2
-    ; sta ARG1
-    ; lda #<$3100
-    ; sta ARG2
-    ; lda #>$3100
-    ; sta ARG3
-    ldy #10
-    jsr memcopy
 
 
     jsr ps2kb::init
     stz kb::status
     StoreDByte process_scancode,ps2kb::scancode_handler
-    jsr ps2kb::begin_receive
+    ; jsr ps2kb::begin_receive
+    JsrIndirect @a1, @a2
+    stp
+    stp
+    stp
+    stp
+    stp
+@a1:
+    lda #'1'
+    jsr lcd::print_char
+    rts
+    stp
+    stp
+    stp
+    stp
+@a2:
+    lda #'2'
+    jsr lcd::print_char
 
     lda #'%'
     jsr lcd::print_char
@@ -84,17 +79,17 @@ CODE_START:
 @noscancode:
     bbr5 kb::status, @shift_off
 @shift_on:
-    DEBUG_LED_ON 0
+    ; DEBUG_LED_ON 0
     bra @check_caps
 @shift_off:
-    DEBUG_LED_OFF 0
+    ; DEBUG_LED_OFF 0
 @check_caps:
     bbr4 kb::status, @caps_off
 @caps_on:
-    DEBUG_LED_ON 2
+    ; DEBUG_LED_ON 2
     bra @read_keypad
 @caps_off:
-    DEBUG_LED_OFF 2
+    ; DEBUG_LED_OFF 2
 @read_keypad:
     lda kp::_DEBUG_VAL
     jeq @loop
@@ -113,6 +108,8 @@ CODE_START:
     beq @lB
     cmp #'C'
     beq @lC
+    cmp #'D'
+    beq @lD
     jsr lcd::print_char
     jmp @loop
 @l1:
@@ -133,8 +130,8 @@ CODE_START:
     iny
     jmp @loop
 @lA:
-    lda ps2kb::VIA + IO::SR
+    jsr ps2kb::begin_receive
-    jsr lcd::print_char
+    ; StoreDByte _receive_irq_timer_handler, $3100
     jmp @loop
 @lB:
     ; Printf "kc%x;", out_str, kb::scancode
@@ -149,26 +146,23 @@ CODE_START:
 @lC:
     jsr lcd::clear
     jmp @loop
+@lD:
+    lda ps2kb::STATUS::SEND_CMD
+    sta ps2kb::status
+    ; lda #$ed
+    ; ldx #%00000111
+    ; lda #$f6
+    ; lda #$ff
+    lda #$ee
+    ; ldx #$ee
+    ; ldx #0
+    ldx #ps2kb::NO_DATA
+    sta ps2kb::send_cmd
+    stx ps2kb::send_data
+    jsr _send_byte
+    ; jsr ps2kb::send_command;
+    jmp @loop
 
-
-; key_read: .res 2
-; scancode:  .res 1
-kb_irq1:
-    ; lda #'!'
-    ; jsr lcd::print_char
-    jsr ps2kb::_receive_irq_shift_reg_handler
-    ; lda #':'
-    ; jsr lcd::print_char
-    rts
-.byte '='
-kb_irq2:
-    ; lda #'?'
-    ; jsr lcd::print_char
-    ; jsr kb::on_timer_irq
-    jsr ps2kb::_receive_irq_timer_handler
-    ; lda #';'
-    ; jsr lcd::print_char
-    rts
 .byte '@'
 
 .proc process_scancode
@@ -297,10 +291,199 @@ kb_irq2:
     rts
 .endproc
 
+;;********************************************************************************
+;; @macro Enable the clock signal from the keyboard
+;; @modifies: A
+;; @details
+;;  Stop pulling the keyboards clock low
+;;********************************************************************************
+.macro _EnableClock
+    ; set pin to input
+    lda ps2kb::VIA + ps2kb::PULL_DDR
+    and #<~ps2kb::PULL_MASK_CLK
+    sta ps2kb::VIA + ps2kb::PULL_DDR
+.endmacro
+
+;;********************************************************************************
+;; @macro Disable the clock signal from the keyboard
+;; @modifies: A
+;; @details
+;;  Pulls the keyboards clock low
+;;********************************************************************************
+.macro _DisableClock
+    ; set pin to output
+    lda ps2kb::VIA + ps2kb::PULL_DDR
+    ora #ps2kb::PULL_MASK_CLK
+    sta ps2kb::VIA + ps2kb::PULL_DDR
+    ; set pin low
+    lda ps2kb::VIA + ps2kb::PULL_REG
+    and #<~ps2kb::PULL_MASK_CLK
+    sta ps2kb::VIA + ps2kb::PULL_REG
+.endmacro
+
+
+.proc _send_byte
+    pha
+        IO_DisableIRQ ps2kb::VIA, (IO::IRQ::T2 | IO::IRQ::SR)
+
+        _DisableClock
+
+        lda #'X'
+        jsr lcd::print_char
+
+        ; set shift register to output
+        lda ps2kb::VIA + IO::ACR
+        and #<~IO::ACR_MASK::SR
+        ora #IO::ACR::SR_SOUT_PHIE
+        sta ps2kb::VIA + IO::ACR
+        stz ps2kb::VIA + IO::SR
+        ; shift out the startbit = data low
+        _EnableClock    
+        _DisableClock
+        ; reset shift register to start the count at 0 again
+        lda #IO::ACR::SR_SOUT_PHIE
+        trb ps2kb::VIA + IO::ACR
+        tsb ps2kb::VIA + IO::ACR
+
+        ; setup the low timer byte
+        lda #<ps2kb::TIMER_SEND
+        sta ps2kb::VIA + IO::T2CL
+
+        ; setup interrupt handlers
+        StoreDByte ps2kb::_send_irq_shift_reg_handler, $3000
+        ; StoreDByte _send_irq_cb2_handler, $3020
+        ; StoreDByte _send_irq_cb1_handler, $3040
+        StoreDByte _send_irq_timer_handler, $3060
+    pla
+    Reverse A
+    pha
+        CalculateOddParity
+        ror     ; Parity -> C
+        lda #$ff
+        ror     ; Parity -> bit 7, rest = 1
+        sta ps2kb::send_last_bits  ; loaded into SR by irq handler
+    pla
+    sta ps2kb::VIA + IO::SR
+    IO_EnableIRQ ps2kb::VIA, IO::IRQ::SR
+    _EnableClock    
+    rts
+.endproc
+
+; .proc _send_irq_shift_reg_handler
+;     lda ps2kb::send_last_bits
+;     sta ps2kb::VIA + IO::SR
+
+;     IO_DisableIRQ ps2kb::VIA, IO::IRQ::SR
+;     IO_EnableIRQ ps2kb::VIA, IO::IRQ::T2
+;     ; start timer, low order count already in latch after init
+;     lda #>ps2kb::TIMER_SEND
+;     sta ps2kb::VIA + IO::T2CH
+;     rts
+; .endproc
+
+.proc _send_irq_timer_handler
+    lda ps2kb::VIA + IO::T2CL  ; clear interrupt flag
+    IO_DisableIRQ ps2kb::VIA, IO::IRQ::T2
+
+    ; disable shift register
+    lda ps2kb::VIA + IO::ACR
+    and #<~IO::ACR_MASK::SR
+    sta ps2kb::VIA + IO::ACR
+    bra _send_done
+
+    ; lda ps2kb::VIA + IO::IFR
+    ; jsr str::uint8_to_hex_str
+    ; jsr lcd::print_char
+    ; txa 
+    ; jsr lcd::print_char
+    rts
+.endproc
+
+; @details
+;  Set the SEND_CMD_WAIT status bit the first time
+;  and jump to _send_done the second time it is called
+; .proc _send_irq_cb1_handler
+;     ; clear the flag and disable interrupts
+;     ; DEBUG_LED_ON 1
+;     lda #'i'
+;     jsr lcd::print_char
+;     stp
+
+;     lda #IO::IRQ::CB1
+;     sta ps2kb::VIA + IO::IFR
+;     sta ps2kb::VIA + IO::IER
+;     ; DEBUG_LED_OFF 1
+;     bra _check_done
+; .endproc
+; .proc _send_irq_cb2_handler
+;     ; DEBUG_LED_ON 0
+;     ; lda #'I'
+;     ; jsr lcd::print_char
+
+;     lda #IO::IRQ::CB2
+;     sta ps2kb::VIA + IO::IFR
+;     sta ps2kb::VIA + IO::IER
+;     ; DEBUG_LED_OFF 0
+;     bra _send_done
+;     bra _check_done
+; .endproc
+
+; .proc _check_done
+;     ; check if done, by checking if SEND_CMD_WAIT bit is set
+;     lda #ps2kb::STATUS::SEND_CMD_WAIT
+;     tsb ps2kb::status
+;     bne _send_done     ; SEND_CMD_WAIT was already set
+;     rts
+; .endproc
+
+.proc _send_done
+    _DisableClock           ; disable keyboard while setting up receive
+    lda #'D'
+    jsr lcd::print_char
+    ; Sleep 1
+    lda ps2kb::status
+    and #ps2kb::STATUS::SEND_CMD
+    beq @status_send_data   ; data byte already sent
+@status_send_cmd:
+    lda #ps2kb::STATUS::SEND_DATA
+    lda ps2kb::status
+    ; check if a data byte needs to be sent
+    lda ps2kb::send_data
+    beq @send_data          ; if 0 
+    cmp #ps2kb::NO_DATA
+    beq @receive_answer     ; if not NO_DATA
+@send_data:
+    jmp _send_byte          ; send the data
+@status_send_data:
+@receive_answer:
+    _DisableClock           ; disable keyboard while setting up receive
+    DEBUG_LED_ON 0
+    lda #ps2kb::STATUS::RECEIVE_ANSWER
+    sta ps2kb::status
+    jmp ps2kb::begin_receive
+.endproc
+
+
+.proc _process_cmd_answer 
+    Strf fmt_answer, out_str, ps2kb::send_cmd, ps2kb::send_data, ps2kb::scancode
+    PrintNC out_str
+    DEBUG_LED_ON 1
+    stz ps2kb::scancode
+    lda ps2kb::prev_status
+    sta ps2kb::status
+    ; set pin to input
+    ; lda ps2kb::VIA + ps2kb::CLK_PULL_DDR
+    ; and #<~ps2kb::CLK_PULL_MASK
+    ; sta ps2kb::VIA + ps2kb::CLK_PULL_DDR
+    rts
+.endproc
+
+
 out_idx: .res 1
 out_str: .res 40
 char:           .res 1
 keycode:        .res 1
 keycode_flags:  .res 1
-fmt_codechar: .asciiz "%x %x %c "
+fmt_codechar:   .asciiz "%x %x %c "
-fmt_code: .asciiz "%x %x   "
+fmt_code:       .asciiz "%x %x   "
+fmt_answer:     .asciiz "%x-%x>%x"

system/ps2_keyboard.h65

@@ -30,20 +30,31 @@ INCLUDE_PS2_KEYBOARD = 1
 
 .scope ps2kb
 Import ps2kb,init,begin_receive,send_command,scancode,status,scancode_handler
-Import ps2kb, _receive_irq_shift_reg_handler, _receive_irq_timer_handler
+Import ps2kb, _receive_irq_shift_reg_handler, _receive_irq_timer_handler, _send_byte, _send_irq_shift_reg_handler, _send_irq_timer_handler,
+Import ps2kb, send_last_bits, send_cmd, send_data, key_read, prev_status
 
 VIA = IO1
-TIMER = 230  ; 230 ms (@1MHz)
+; Enough time must pass for 3 bits to be shifted in.
+TIMER_RECV = 230  ; 230 ms (@1MHz)
+; Enough time must pass for one bit must be shifted out (parity),
+; but at most two (parity+stop).
+; After that, the interrupt must have happened because the keyboard will pull data low.
+; At that point, the SR needs to be set to input again
+TIMER_SEND = 230  ; 180 ms (@1MHz)
 ; use RA4 to pull the clock low
-CLK_PULL_MASK= %00001000
+PULL_REG = IO::RANH
-CLK_PULL_R	 = IO::RANH
+PULL_DDR = IO::DDRA
-CLK_PULL_DDR = IO::DDRA
 
+PULL_MASK_CLK = %00010000
+; PULL_MASK_DAT = %00001000
+NO_DATA = $ff   ; indicates that no data byte should be send
 
 .enum STATUS
     RECEIVE_KEYS	= %10000000
     RECEIVE_ANSWER	= %01000000
     SEND_CMD   		= %00100000
+    SEND_DATA   	= %00010000
+    SEND_CMD_WAIT   = %00001000
     NONE			= %00000000
 .endenum
 .endscope

system/ps2_keyboard.s65

@@ -3,10 +3,12 @@
 .include "lcd.h65"
 .include "parity.h65"
 Export ps2kb,init,begin_receive,send_command,scancode,status,scancode_handler
-Export ps2kb, _receive_irq_shift_reg_handler, _receive_irq_timer_handler
+Export ps2kb, _receive_irq_shift_reg_handler, _receive_irq_timer_handler, _send_byte, _send_irq_shift_reg_handler, _send_irq_timer_handler,
+Export ps2kb, send_last_bits, send_cmd, send_data, key_read, prev_status
 
 .bss
 status:                 .res 1
+prev_status:            .res 1
 send_last_bits:         .res 1
 send_data:              .res 1
 send_cmd:               .res 1
@@ -24,16 +26,9 @@ scancode_handler:       .res 2
 ;;********************************************************************************
 .macro _EnableClock
     ; set pin to input
-    lda ps2kb::VIA + ps2kb::CLK_PULL_DDR
+    lda ps2kb::VIA + ps2kb::PULL_DDR
-    and #<~ps2kb::CLK_PULL_MASK
+    and #<~ps2kb::PULL_MASK_CLK
-    sta ps2kb::VIA + ps2kb::CLK_PULL_DDR
+    sta ps2kb::VIA + ps2kb::PULL_DDR
-.endmacro
-
-.macro _DisableTimerIRQ
-    ; set pin to input
-    lda ps2kb::VIA + ps2kb::CLK_PULL_DDR
-    and #<~ps2kb::CLK_PULL_MASK
-    sta ps2kb::VIA + ps2kb::CLK_PULL_DDR
 .endmacro
 
 ;;********************************************************************************
@@ -44,17 +39,45 @@ scancode_handler:       .res 2
 ;;********************************************************************************
 .macro _DisableClock
     ; set pin to output
-    lda ps2kb::VIA + ps2kb::CLK_PULL_DDR
+    lda ps2kb::VIA + ps2kb::PULL_DDR
-    ora #ps2kb::CLK_PULL_MASK
+    ora #ps2kb::PULL_MASK_CLK
-    sta ps2kb::VIA + ps2kb::CLK_PULL_DDR
+    sta ps2kb::VIA + ps2kb::PULL_DDR
     ; set pin low
-    lda ps2kb::VIA + ps2kb::CLK_PULL_R
+    lda ps2kb::VIA + ps2kb::PULL_REG
-    and #<~ps2kb::CLK_PULL_MASK
+    and #<~ps2kb::PULL_MASK_CLK
-    sta ps2kb::VIA + ps2kb::CLK_PULL_R
+    sta ps2kb::VIA + ps2kb::PULL_REG
+.endmacro
+
+
+;;********************************************************************************
+;; @macro Stop pulling the keyboard data pin low
+;; @modifies: A
+;;********************************************************************************
+.macro _StopPullDataLow
+    ; set pin to input
+    lda ps2kb::VIA + ps2kb::PULL_DDR
+    and #<~ps2kb::PULL_MASK_DAT
+    sta ps2kb::VIA + ps2kb::PULL_DDR
+.endmacro
+
+;;********************************************************************************
+;; @macro Pull the keyboard data pin low
+;; @modifies: A
+;;********************************************************************************
+.macro _PullDataLow
+    ; set pin to output
+    lda ps2kb::VIA + ps2kb::PULL_DDR
+    ora #ps2kb::PULL_MASK_DAT
+    sta ps2kb::VIA + ps2kb::PULL_DDR
+    ; set pin low
+    lda ps2kb::VIA + ps2kb::PULL_REG
+    and #<~ps2kb::PULL_MASK_DAT
+    sta ps2kb::VIA + ps2kb::PULL_REG
 .endmacro
 
 
 .proc init
+    _DisableClock
     stz key_read 
     stz key_read+1
     stz scancode
@@ -64,10 +87,6 @@ scancode_handler:       .res 2
     and #<~IO::ACR_MASK::SR
     ora #IO::ACR::T2_IRQ_LOAD
     sta ps2kb::VIA + IO::ACR
-    ; the 3 last bits take about 230us, at @1MHz => wait 230 cycles and then the shift register
-    ; (this could be shorter since the it takes a few cycles after the interrupt)
-    lda #<ps2kb::TIMER
-    sta ps2kb::VIA + IO::T2CL
     ; load this rts as scancode_handler
     StoreDByte @rts, scancode_handler
 @rts:
@@ -85,25 +104,32 @@ scancode_handler:       .res 2
 .proc begin_receive
     ; disable timer interrupts (this might be called while waiting on the last 3 bits)
     IO_DisableIRQ ps2kb::VIA, IO::IRQ::T2
-    ; set shift register to shift in under external clock on CB1
+    ; (re)set shift register to shift in under external clock on CB1
     lda ps2kb::VIA + IO::ACR
     and #<~IO::ACR_MASK::SR
+    sta ps2kb::VIA + IO::ACR    ; important, disabling SR resets the count
     ora #IO::ACR::SR_SIN_PHIE
     sta ps2kb::VIA + IO::ACR
     stz key_read
     stz key_read+1
     stz scancode
     bit status
+
+    ; the 3 last bits take about 230us, at @1MHz => wait 230 cycles and then the shift register
+    ; (this could be shorter since the it takes a few cycles after the interrupt)
+    lda #<ps2kb::TIMER_RECV
+    sta ps2kb::VIA + IO::T2CL
     ; set to RECEIVE_KEYS only if RECEIVE_ANSWER is not set
-    bvs @receive_answer
+    bvs @status_set
     lda #ps2kb::STATUS::RECEIVE_KEYS
     sta status
-@receive_answer:
+@status_set:
+    ; todo setup irq handlers
+    StoreDByte _receive_irq_shift_reg_handler, $3000
+    StoreDByte _receive_irq_timer_handler, $3060
 
     _EnableClock
 
-    ; todo setup irq handlers
-
     IO_EnableIRQ ps2kb::VIA, IO::IRQ::SR
     ; reset and start SR
     stz ps2kb::VIA + IO::SR
@@ -132,7 +158,7 @@ scancode_handler:       .res 2
     IO_DisableIRQ ps2kb::VIA, IO::IRQ::SR
     IO_EnableIRQ ps2kb::VIA, IO::IRQ::T2
     ; start timer, low order count already in latch after init
-    lda #>ps2kb::TIMER
+    lda #>ps2kb::TIMER_RECV
     sta ps2kb::VIA + IO::T2CH
     rts
 .endproc
@@ -150,7 +176,7 @@ scancode_handler:       .res 2
 ;;********************************************************************************
 .proc _receive_irq_timer_handler
     lda ps2kb::VIA + IO::SR
-    sta key_read + 1
+    sta key_read+1
 
     lda ps2kb::VIA + IO::T2CL  ; clear interrupt flag
 
@@ -173,10 +199,13 @@ scancode_handler:       .res 2
     rol             ; C  -> bit 0, startbit -> C
     Reverse A
     sta scancode
-    CalculateOddParity
+
-    eor key_read+1  ; if bit 0 is 1 - parity error
+    ; check parity
-    and #1          ; bit 1 is still D7
+    ; CalculateOddParity
-    bne @parity_error
+    ; eor key_read+1  ; if bit 0 is 1 - parity error
+    ; and #1          ; bit 1 is still D7
+    ; bne @parity_error
+
     ; check what to do with the scancode
     bit status
     bcc @status_not_receive_keys
@@ -198,15 +227,15 @@ scancode_handler:       .res 2
 ;; @function Send a command to the keyboard
 ;; @modifies: A,X,Y
 ;; @param A: The command byte
-;; @param X: The data byte or 0 if only the command byte should be sent
+;; @param X: The data byte or NO_DATA if only the command byte should be sent
 ;;********************************************************************************
 .proc send_command
+    ldy status
+    sty prev_status
+    ldy #ps2kb::STATUS::SEND_CMD
+    sty status
     sta send_cmd        ; store if it needs to be resent
-    cpx #0
-    beq @jmp_send_byte
-@store_data:
     stx send_data
-@jmp_send_byte:
     jmp _send_byte
 .endproc
 
@@ -217,36 +246,51 @@ scancode_handler:       .res 2
 ;; @param A: The byte to send
 ;; @details
 ;;  - pull clock low to stop keyboard transmissions
-;;  - setup shift register to shift out
+;;  - setup SR to shift out
-;;  - put startbit + D0-6 in shift register
+;;  - pull data low (by shifting out a zero)
-;;  - store D7 + parity + stopbit in memory
+;;  - reset SR
-;;  - TODO setup SR and T2 interrupt handlers
+;;  - put (reversed) byte in SR
+;;  - put parity + stopbit(s) in send_last_bits variable
+;;  - setup interrupt handlers
+;;  - enable clock
 ;;********************************************************************************
 .proc _send_byte
     pha
-        IO_DisableIRQ ps2kb::VIA, IO::IRQ::T2
+        IO_DisableIRQ ps2kb::VIA, (IO::IRQ::T2 | IO::IRQ::SR)
+
         _DisableClock
-        ; (re)set shift register to shift out under external clock on CB1
+
+        ; set shift register to output
         lda ps2kb::VIA + IO::ACR
         and #<~IO::ACR_MASK::SR
         ora #IO::ACR::SR_SOUT_PHIE
         sta ps2kb::VIA + IO::ACR
-        IO_EnableIRQ ps2kb::VIA, IO::IRQ::SR
+        stz ps2kb::VIA + IO::SR
+        ; shift out the startbit = data low
+        _EnableClock    
+        _DisableClock
+        ; reset shift register to start the count at 0 again
+        lda #IO::ACR::SR_SOUT_PHIE
+        trb ps2kb::VIA + IO::ACR
+        tsb ps2kb::VIA + IO::ACR
+
+        ; setup the low timer byte
+        lda #<ps2kb::TIMER_SEND
+        sta ps2kb::VIA + IO::T2CL
+
+        StoreDByte _send_irq_shift_reg_handler, $3000
+        StoreDByte _send_irq_timer_handler, $3006
     pla
+    Reverse A
     pha
-        ; split into the 11 bits
         CalculateOddParity
-        tax
+        ror     ; Parity -> C
+        lda #$ff
+        ror     ; Parity -> bit 7, rest = 1
+        sta ps2kb::send_last_bits  ; loaded into SR by irq handler
     pla
-    clc     ; C = 0 (startbi)
-    rol     ; C -> bit 0, D7 -> C
     sta ps2kb::VIA + IO::SR
-    txa
+    IO_EnableIRQ ps2kb::VIA, IO::IRQ::SR
-    ror     ; C -> bit 0 (D7)
-    ora #%00000100  ; set stopbit
-    ; A = 000001P7  where 7 = D7, P = Parity
-    sta send_last_bits  ; loaded into SR by irq handler
-    ; stop pulling clk low, which causes the startbit to be shifted out 
     _EnableClock    
     rts
 .endproc
@@ -262,17 +306,13 @@ scancode_handler:       .res 2
 ;;  - start timer 2
 ;;********************************************************************************
 .proc _send_irq_shift_reg_handler
-    lda send_last_bits
+    lda ps2kb::send_last_bits
     sta ps2kb::VIA + IO::SR
 
-    ; disable SR interrupts
+    IO_DisableIRQ ps2kb::VIA, IO::IRQ::SR
-    lda #IO::IRQ::SR
+    IO_EnableIRQ ps2kb::VIA, IO::IRQ::T2
-    sta ps2kb::VIA + IO::IER
-    ; enable timer interrupts
-    lda #(IO::IRQ::IRQ | IO::IRQ::T2)
-    sta ps2kb::VIA + IO::IER
     ; start timer, low order count already in latch after init
-    lda #>ps2kb::TIMER
+    lda #>ps2kb::TIMER_SEND
     sta ps2kb::VIA + IO::T2CH
     rts
 .endproc
@@ -293,21 +333,20 @@ scancode_handler:       .res 2
 .proc _send_irq_timer_handler
     lda ps2kb::VIA + IO::T2CL  ; clear interrupt flag
     IO_DisableIRQ ps2kb::VIA, IO::IRQ::T2
-    ; no SR reset necessary, will be done in begin_receive or send_byte
 
-    lda send_data
+    lda ps2kb::send_data
     beq @receive
-    stz send_data
+    stz ps2kb::send_data
     jmp _send_byte
     rts
 @receive:
+    _DisableClock   ; disable keyboard while setting up receive
     lda #ps2kb::STATUS::RECEIVE_ANSWER
-    sta status
+    sta ps2kb::status
-    jmp begin_receive
+    jmp ps2kb::begin_receive
 .endproc
 
 
 .proc _process_cmd_answer
-@success:
+    jmp ($3200)
-    rts
 .endproc