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Cleanup & Add more comments

This commit is contained in:
Stefano Furiosi 2017-02-12 18:53:33 -08:00
parent 93be412fd7
commit d2385a9d3f
4 changed files with 301 additions and 269 deletions
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258
ASM/woz_monitor_dasm.asm Normal file
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@ -0,0 +1,258 @@
; dasm woz_monitor_masm.asm -orom.o -lrom.lst -srom.sym
;-------------------------------------------------------------------------
;
; The WOZ Monitor for the Apple 1
; Written by Steve Wozniak 1976
;
;-------------------------------------------------------------------------
processor 6502
org $FF00
;-------------------------------------------------------------------------
; Memory declaration
;-------------------------------------------------------------------------
XAML equ $24 ;Last "opened" location Low
XAMH equ $25 ;Last "opened" location High
STL equ $26 ;Store address Low
STH equ $27 ;Store address High
L equ $28 ;Hex value parsing Low
H equ $29 ;Hex value parsing High
YSAV equ $2A ;Used to see if hex value is given
MODE equ $2B ;$00=XAM, $7F=STOR, $AE=BLOCK XAM
IN equ $0200,$027F ;Input buffer
KBD equ $D010 ;PIA.A keyboard input
KBDCR equ $D011 ;PIA.A keyboard control register
DSP equ $D012 ;PIA.B display output register
DSPCR equ $D013 ;PIA.B display control register
; KBD b7..b0 are inputs, b6..b0 is ASCII input, b7 is constant high
; Programmed to respond to low to high KBD strobe
; DSP b6..b0 are outputs, b7 is input
; CB2 goes low when data is written, returns high when CB1 goes high
; Interrupts are enabled, though not used. KBD can be jumpered to IRQ,
; whereas DSP can be jumpered to NMI.
;-------------------------------------------------------------------------
; Constants
;-------------------------------------------------------------------------
BS equ $DF ;Backspace key, arrow left key
CR equ $8D ;Carriage Return
ESC equ $9B ;ESC key
PROMPT equ $5C ;Prompt character \
;-------------------------------------------------------------------------
; Let's get started
;
; Remark the RESET routine is only to be entered by asserting the RESET
; line of the system. This ensures that the data direction registers
; are selected.
;-------------------------------------------------------------------------
RESET cld ;Clear decimal arithmetic mode
cli
ldy #%01111111 ;Mask for DSP data direction reg
sty DSP ;(DDR mode is assumed after reset)
lda #%10100111 ;KBD and DSP control register mask
sta KBDCR ;Enable interrupts, set CA1, CB1 for
sta DSPCR ;positive edge sense/output mode.
; Program falls through to the GETLINE routine to save some program bytes
; Please note that Y still holds $7F, which will cause an automatic Escape
;-------------------------------------------------------------------------
; The GETLINE process
;-------------------------------------------------------------------------
NOTCR cmp #BS ;Backspace key?
beq BACKSPACE ;Yes
cmp #ESC ;ESC?
beq ESCAPE ;Yes
iny ;Advance text index
bpl NEXTCHAR ;Auto ESC if line longer than 127
ESCAPE lda #PROMPT ;Print prompt character
jsr ECHO ;Output it.
GETLINE lda #CR ;Send CR
jsr ECHO
ldy #0+1 ;Start a new input line
BACKSPACE dey ;Backup text index
bmi GETLINE ;Oops, line's empty, reinitialize
NEXTCHAR lda KBDCR ;Wait for key press
bpl NEXTCHAR ;No key yet!
lda KBD ;Load character. B7 should be '1'
sta IN,Y ;Add to text buffer
jsr ECHO ;Display character
cmp #CR
bne NOTCR ;It's not CR!
; Line received, now let's parse it
ldy #-1 ;Reset text index
lda #0 ;Default mode is XAM
tax ;X=0
SETSTOR asl ;Leaves $7B if setting STOR mode
SETMODE sta MODE ;Set mode flags
BLSKIP iny ;Advance text index
NEXTITEM lda IN,Y ;Get character
cmp #CR
beq GETLINE ;We're done if it's CR!
cmp #"."
bcc BLSKIP ;Ignore everything below "."!
beq SETMODE ;Set BLOCK XAM mode ("." = $AE)
cmp #":"
beq SETSTOR ;Set STOR mode! $BA will become $7B
cmp #"R"
beq RUN ;Run the program! Forget the rest
stx L ;Clear input value (X=0)
stx H
sty YSAV ;Save Y for comparison
; Here we're trying to parse a new hex value
NEXTHEX lda IN,Y ;Get character for hex test
eor #$B0 ;Map digits to 0-9
cmp #9+1 ;Is it a decimal digit?
bcc DIG ;Yes!
adc #$88 ;Map letter "A"-"F" to $FA-FF
cmp #$FA ;Hex letter?
bcc NOTHEX ;No! Character not hex
DIG asl
asl ;Hex digit to MSD of A
asl
asl
ldx #4 ;Shift count
HEXSHIFT asl ;Hex digit left, MSB to carry
rol L ;Rotate into LSD
rol H ;Rotate into MSD's
dex ;Done 4 shifts?
bne HEXSHIFT ;No, loop
iny ;Advance text index
bne NEXTHEX ;Always taken
NOTHEX cpy YSAV ;Was at least 1 hex digit given?
beq ESCAPE ;No! Ignore all, start from scratch
bit MODE ;Test MODE byte
bvc NOTSTOR ;B6=0 is STOR, 1 is XAM or BLOCK XAM
; STOR mode, save LSD of new hex byte
lda L ;LSD's of hex data
sta (STL,X) ;Store current 'store index'(X=0)
inc STL ;Increment store index.
bne NEXTITEM ;No carry!
inc STH ;Add carry to 'store index' high
TONEXTITEM jmp NEXTITEM ;Get next command item.
;-------------------------------------------------------------------------
; RUN user's program from last opened location
;-------------------------------------------------------------------------
RUN jmp (XAML) ;Run user's program
;-------------------------------------------------------------------------
; We're not in Store mode
;-------------------------------------------------------------------------
NOTSTOR bmi XAMNEXT ;B7 = 0 for XAM, 1 for BLOCK XAM
; We're in XAM mode now
ldx #2 ;Copy 2 bytes
SETADR lda L-1,X ;Copy hex data to
sta STL-1,X ; 'store index'
sta XAML-1,X ; and to 'XAM index'
dex ;Next of 2 bytes
bne SETADR ;Loop unless X = 0
; Print address and data from this address, fall through next bne.
NXTPRNT bne PRDATA ;NE means no address to print
lda #CR ;Print CR first
jsr ECHO
lda XAMH ;Output high-order byte of address
jsr PRBYTE
lda XAML ;Output low-order byte of address
jsr PRBYTE
lda #":" ;Print colon
jsr ECHO
PRDATA lda #" " ;Print space
jsr ECHO
lda (XAML,X) ;Get data from address (X=0)
jsr PRBYTE ;Output it in hex format
XAMNEXT stx MODE ;0 -> MODE (XAM mode).
lda XAML ;See if there's more to print
cmp L
lda XAMH
sbc H
bcs TONEXTITEM ;Not less! No more data to output
inc XAML ;Increment 'examine index'
bne MOD8CHK ;No carry!
inc XAMH
MOD8CHK lda XAML ;If address MOD 8 = 0 start new line
and #%00000111
bpl NXTPRNT ;Always taken.
;-------------------------------------------------------------------------
; Subroutine to print a byte in A in hex form (destructive)
;-------------------------------------------------------------------------
PRBYTE pha ;Save A for LSD
lsr
lsr
lsr ;MSD to LSD position
lsr
jsr PRHEX ;Output hex digit
pla ;Restore A
; Fall through to print hex routine
;-------------------------------------------------------------------------
; Subroutine to print a hexadecimal digit
;-------------------------------------------------------------------------
PRHEX and #%00001111 ;Mask LSD for hex print
ora #"0" ;Add "0"
cmp #"9"+1 ;Is it a decimal digit?
bcc ECHO ;Yes! output it
adc #6 ;Add offset for letter A-F
; Fall through to print routine
;-------------------------------------------------------------------------
; Subroutine to print a character to the terminal
;-------------------------------------------------------------------------
ECHO bit DSP ;DA bit (B7) cleared yet?
bmi ECHO ;No! Wait for display ready
sta DSP ;Output character. Sets DA
rts
;-------------------------------------------------------------------------
; Vector area
;-------------------------------------------------------------------------
dc.w $0000 ;Unused, what a pity
NMI_VEC dc.w $0F00 ;NMI vector
RESET_VEC dc.w RESET ;RESET vector
IRQ_VEC dc.w $0000 ;IRQ vector
;-------------------------------------------------------------------------

258
ASM/woz_monitor_masm.asm
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@ -1,258 +0,0 @@
; dasm woz_monitor_masm.asm -orom.o -lrom.lst -srom.sym
;-------------------------------------------------------------------------
;
; The WOZ Monitor for the Apple 1
; Written by Steve Wozniak 1976
;
;-------------------------------------------------------------------------
processor 6502
org $FF00
;-------------------------------------------------------------------------
; Memory declaration
;-------------------------------------------------------------------------
XAML equ $24 ;Last "opened" location Low
XAMH equ $25 ;Last "opened" location High
STL equ $26 ;Store address Low
STH equ $27 ;Store address High
L equ $28 ;Hex value parsing Low
H equ $29 ;Hex value parsing High
YSAV equ $2A ;Used to see if hex value is given
MODE equ $2B ;$00=XAM, $7F=STOR, $AE=BLOCK XAM
IN equ $0200,$027F ;Input buffer
KBD equ $D010 ;PIA.A keyboard input
KBDCR equ $D011 ;PIA.A keyboard control register
DSP equ $D012 ;PIA.B display output register
DSPCR equ $D013 ;PIA.B display control register
; KBD b7..b0 are inputs, b6..b0 is ASCII input, b7 is constant high
; Programmed to respond to low to high KBD strobe
; DSP b6..b0 are outputs, b7 is input
; CB2 goes low when data is written, returns high when CB1 goes high
; Interrupts are enabled, though not used. KBD can be jumpered to IRQ,
; whereas DSP can be jumpered to NMI.
;-------------------------------------------------------------------------
; Constants
;-------------------------------------------------------------------------
BS equ $DF ;Backspace key, arrow left key
CR equ $8D ;Carriage Return
ESC equ $9B ;ESC key
PROMPT equ "\" ;Prompt character
;-------------------------------------------------------------------------
; Let's get started
;
; Remark the RESET routine is only to be entered by asserting the RESET
; line of the system. This ensures that the data direction registers
; are selected.
;-------------------------------------------------------------------------
RESET CLD ;Clear decimal arithmetic mode
CLI
LDY #%01111111 ;Mask for DSP data direction reg
STY DSP ;(DDR mode is assumed after reset)
LDA #%10100111 ;KBD and DSP control register mask
STA KBDCR ;Enable interrupts, set CA1, CB1 for
STA DSPCR ;positive edge sense/output mode.
; Program falls through to the GETLINE routine to save some program bytes
; Please note that Y still holds $7F, which will cause an automatic Escape
;-------------------------------------------------------------------------
; The GETLINE process
;-------------------------------------------------------------------------
NOTCR CMP #BS ;Backspace key?
BEQ BACKSPACE ;Yes
CMP #ESC ;ESC?
BEQ ESCAPE ;Yes
INY ;Advance text index
BPL NEXTCHAR ;Auto ESC if line longer than 127
ESCAPE LDA #PROMPT ;Print prompt character
JSR ECHO ;Output it.
GETLINE LDA #CR ;Send CR
JSR ECHO
LDY #0+1 ;Start a new input line
BACKSPACE DEY ;Backup text index
BMI GETLINE ;Oops, line's empty, reinitialize
NEXTCHAR LDA KBDCR ;Wait for key press
BPL NEXTCHAR ;No key yet!
LDA KBD ;Load character. B7 should be '1'
STA IN,Y ;Add to text buffer
JSR ECHO ;Display character
CMP #CR
BNE NOTCR ;It's not CR!
; Line received, now let's parse it
LDY #-1 ;Reset text index
LDA #0 ;Default mode is XAM
TAX ;X=0
SETSTOR ASL ;Leaves $7B if setting STOR mode
SETMODE STA MODE ;Set mode flags
BLSKIP INY ;Advance text index
NEXTITEM LDA IN,Y ;Get character
CMP #CR
BEQ GETLINE ;We're done if it's CR!
CMP #"."
BCC BLSKIP ;Ignore everything below "."!
BEQ SETMODE ;Set BLOCK XAM mode ("." = $AE)
CMP #":"
BEQ SETSTOR ;Set STOR mode! $BA will become $7B
CMP #"R"
BEQ RUN ;Run the program! Forget the rest
STX L ;Clear input value (X=0)
STX H
STY YSAV ;Save Y for comparison
; Here we're trying to parse a new hex value
NEXTHEX LDA IN,Y ;Get character for hex test
EOR #$B0 ;Map digits to 0-9
CMP #9+1 ;Is it a decimal digit?
BCC DIG ;Yes!
ADC #$88 ;Map letter "A"-"F" to $FA-FF
CMP #$FA ;Hex letter?
BCC NOTHEX ;No! Character not hex
DIG ASL
ASL ;Hex digit to MSD of A
ASL
ASL
LDX #4 ;Shift count
HEXSHIFT ASL ;Hex digit left, MSB to carry
ROL L ;Rotate into LSD
ROL H ;Rotate into MSD's
DEX ;Done 4 shifts?
BNE HEXSHIFT ;No, loop
INY ;Advance text index
BNE NEXTHEX ;Always taken
NOTHEX CPY YSAV ;Was at least 1 hex digit given?
BEQ ESCAPE ;No! Ignore all, start from scratch
BIT MODE ;Test MODE byte
BVC NOTSTOR ;B6=0 is STOR, 1 is XAM or BLOCK XAM
; STOR mode, save LSD of new hex byte
LDA L ;LSD's of hex data
STA (STL,X) ;Store current 'store index'(X=0)
INC STL ;Increment store index.
BNE NEXTITEM ;No carry!
INC STH ;Add carry to 'store index' high
TONEXTITEM JMP NEXTITEM ;Get next command item.
;-------------------------------------------------------------------------
; RUN user's program from last opened location
;-------------------------------------------------------------------------
RUN JMP (XAML) ;Run user's program
;-------------------------------------------------------------------------
; We're not in Store mode
;-------------------------------------------------------------------------
NOTSTOR BMI XAMNEXT ;B7 = 0 for XAM, 1 for BLOCK XAM
; We're in XAM mode now
LDX #2 ;Copy 2 bytes
SETADR LDA L-1,X ;Copy hex data to
STA STL-1,X ; 'store index'
STA XAML-1,X ; and to 'XAM index'
DEX ;Next of 2 bytes
BNE SETADR ;Loop unless X = 0
; Print address and data from this address, fall through next BNE.
NXTPRNT BNE PRDATA ;NE means no address to print
LDA #CR ;Print CR first
JSR ECHO
LDA XAMH ;Output high-order byte of address
JSR PRBYTE
LDA XAML ;Output low-order byte of address
JSR PRBYTE
LDA #":" ;Print colon
JSR ECHO
PRDATA LDA #" " ;Print space
JSR ECHO
LDA (XAML,X) ;Get data from address (X=0)
JSR PRBYTE ;Output it in hex format
XAMNEXT STX MODE ;0 -> MODE (XAM mode).
LDA XAML ;See if there's more to print
CMP L
LDA XAMH
SBC H
BCS TONEXTITEM ;Not less! No more data to output
INC XAML ;Increment 'examine index'
BNE MOD8CHK ;No carry!
INC XAMH
MOD8CHK LDA XAML ;If address MOD 8 = 0 start new line
AND #%00000111
BPL NXTPRNT ;Always taken.
;-------------------------------------------------------------------------
; Subroutine to print a byte in A in hex form (destructive)
;-------------------------------------------------------------------------
PRBYTE PHA ;Save A for LSD
LSR
LSR
LSR ;MSD to LSD position
LSR
JSR PRHEX ;Output hex digit
PLA ;Restore A
; Fall through to print hex routine
;-------------------------------------------------------------------------
; Subroutine to print a hexadecimal digit
;-------------------------------------------------------------------------
PRHEX AND #%00001111 ;Mask LSD for hex print
ORA #"0" ;Add "0"
CMP #"9"+1 ;Is it a decimal digit?
BCC ECHO ;Yes! output it
ADC #6 ;Add offset for letter A-F
; Fall through to print routine
;-------------------------------------------------------------------------
; Subroutine to print a character to the terminal
;-------------------------------------------------------------------------
ECHO BIT DSP ;DA bit (B7) cleared yet?
BMI ECHO ;No! Wait for display ready
STA DSP ;Output character. Sets DA
RTS
;-------------------------------------------------------------------------
; Vector area
;-------------------------------------------------------------------------
dc.w $0000 ;Unused, what a pity
NMI_VEC dc.w $0F00 ;NMI vector
RESET_VEC dc.w RESET ;RESET vector
IRQ_VEC dc.w $0000 ;IRQ vector
;-------------------------------------------------------------------------

7
README.md
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@ -10,13 +10,13 @@ The project is build over Platformio (http://platformio.org/frameworks) but you
## How it works ## How it works
A 65C02S (modern version of the original 6502) is wired on a breadboard. The 6502 is a very simple kind of CPU in terms of I/O and the modern version allow us to suspend the clock at any time in LOW / HIGH state. A 65C02S (modern version of the original 6502) is wired on a breadboard. The 6502 is a very simple kind of CPU in terms of I/O and the modern version allow us to suspend the clock at any time in LOW / HIGH state.
There are 16 Address Pins (A0-A15) each mapping a bit (HIGH/LOW) of an address word. This is how 6502 tell us what address he want to read or write to (RAM/ROM, IO dedicated address spaces). The state of this pins may change at every clock cycle. There are 16 Address Pins (A0-A15) each mapping a bit (HIGH/LOW) of an address word. This is how 6502 tell us which address he want to read or write to (RAM/ROM, IO dedicated address spaces). The state of this pins may change at every clock cycle.
Other 8 pins will carry or expect the 1 Byte data to be stored or read to / from the address above. Other 8 pins will carry or expect the 1 Byte data to be stored or read to / from the address above.
The CPU tell the external world if the data is in read or write state via R/W pin (HIGH=Expect data IN, LOW=Send data OUT). The CPU tell the external world if the data is in read or write state via R/W pin (HIGH=Expect data IN, LOW=Send data OUT).
This is it. This is all you need to interact with a 6502. The CPU expect a clock signal (HIGH/LOW) on pin 37 (PHI2). The modern version of 6502 is able to suspend any activity for an unlimited period of time during a clock cycle, both in LOW or HIGH state (was a little bit more hard with the original CPU). This make a perfect fit to let us drive the CPU via something different from a crystal, in our case, an Arduino, debug any single clock cycle and keep things in sync. That's it. This is all you need to interact with a 6502. The CPU expect a clock signal (HIGH/LOW) on pin 37 (PHI2). The modern version of 6502 is able to suspend any activity for an unlimited period of time during a clock cycle, both in LOW or HIGH state (was a little bit more hard with the original CPU). This make a perfect fit to let us drive the CPU via something different from a crystal, in our case, an Arduino, debug any single clock cycle and keep things in sync.
Knowing the address space where the Apple 1 was mapping the different IO (Ram / ROM / KEYB / DSP), we can simulate the external interfaces (in fact a PIA 6821) and send back & forth as needed the related data via 6502 data bus. That's it. Knowing the address space where the Apple 1 was mapping the different IO (Ram / ROM / KEYB / DSP), we can simulate the external interfaces (in fact a PIA 6821) and send back & forth as needed the related data via 6502 data bus. That's it.
@ -53,8 +53,11 @@ The WOZ monitor asm source and the original apple 1 operation manual are two ver
+--------------+ | +--------------+ |
GND GND
CLOCK_DELAY: A0 - you should connect a potentiometer to A0, this will let you manually sed the clock delay of the 6502.
Note: You may want to put a 100Uf capacitor near the 3.3v & GND lines too. Note: You may want to put a 100Uf capacitor near the 3.3v & GND lines too.
## Serial client recommended settings: ## Serial client recommended settings:
You should be able to use the standard Serial Monitor in the Arduino IDE or or Platformio (Atom) or any other basic serial client. You should be able to use the standard Serial Monitor in the Arduino IDE or or Platformio (Atom) or any other basic serial client.

47
src/main.cpp
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@ -4,14 +4,16 @@
#define CHECK_BIT(var,pos) ((var) & (1<<(pos))) #define CHECK_BIT(var,pos) ((var) & (1<<(pos)))
// General Control settings
const int SERIAL_SPEED = 115200; // Arduino Serial Speed const int SERIAL_SPEED = 115200; // Arduino Serial Speed
const int CLOCK_DELAY_PIN = A0; // Clock delay PIN (potentiometer)
const int CLOCK_PIN = 52; // TO 6502 CLOCK int CLOCK_DELAY = 5; // HIGH / LOW CLOCK STATE DELAY (You can slow down it as much as you want)
const int RW_PIN = 53; // TO 6502 R/W
const int CLOCK_DELAY = 3; // HIGH / LOW CLOCK STATE DELAY (You can slow down it as much as you want)
const char SERIAL_BS = 0x08; const char SERIAL_BS = 0x08;
// 6502 to Arduino Pin Mapping
const int CLOCK_PIN = 52; // TO 6502 CLOCK
const int RW_PIN = 53; // TO 6502 R/W
const int ADDRESS_PINS[] = {44,45,2,3,4,5,6,7,8,9,10,11,12,13,46,47}; // TO ADDRESS PIN 1-15 6502 const int ADDRESS_PINS[] = {44,45,2,3,4,5,6,7,8,9,10,11,12,13,46,47}; // TO ADDRESS PIN 1-15 6502
const int DATA_PINS[] = {33, 34, 35, 36, 37,38, 39, 40}; // TO DATA BUS PIN 0-7 6502 const int DATA_PINS[] = {33, 34, 35, 36, 37,38, 39, 40}; // TO DATA BUS PIN 0-7 6502
@ -49,26 +51,33 @@ const unsigned char BS = 0xDF; // Backspace key, arrow left key (B7 High)
const unsigned char CR = 0x8D; // Carriage Return (B7 High) const unsigned char CR = 0x8D; // Carriage Return (B7 High)
const unsigned char ESC = 0x9B; // ESC key (B7 High) const unsigned char ESC = 0x9B; // ESC key (B7 High)
// 6502 States buffer
unsigned int address; // Current address (from 6502) unsigned int address; // Current address (from 6502)
unsigned char bus_data; // Data Bus value (from 6502) unsigned char bus_data; // Data Bus value (from 6502)
int rw_state; // Current R/W state (from 6502) int rw_state; // Current R/W state (from 6502)
unsigned int pre_address; // Current address (from 6502) // 6502 previous States buffer
unsigned char pre_bus_data; // Data Bus value (from 6502) // We use them to optimize the performance a bit
int pre_rw_state; // Current R/W state (from 6502) unsigned int pre_address; // Previous address (from 6502)
unsigned char pre_bus_data; // Previous Bus value (from 6502)
int pre_rw_state; // Previous R/W state (from 6502)
// Set Arduino Address connected PINS as INPUT
void setupAddressPins() { void setupAddressPins() {
for (int i = 0; i < 16; ++i) { for (int i = 0; i < 16; ++i) {
pinMode(ADDRESS_PINS[i], INPUT); pinMode(ADDRESS_PINS[i], INPUT);
} }
} }
// Set Arduino Bus conneced pins mode as IN or OUT
void setBusMode(int mode) { void setBusMode(int mode) {
for (int i = 0; i < 8; ++i) { for (int i = 0; i < 8; ++i) {
pinMode(DATA_PINS[i], mode); pinMode(DATA_PINS[i], mode);
} }
} }
// Read 6502 Address PINS and store the WORD in our address var
void readAddress() { void readAddress() {
address = 0; address = 0;
for (int i = 0; i < 16; ++i) for (int i = 0; i < 16; ++i)
@ -78,6 +87,7 @@ void readAddress() {
} }
} }
// Read 6502 Data PINS and store the BYTE in our bus_data var
void readData() { void readData() {
bus_data = 0; bus_data = 0;
for (int i = 0; i < 8; ++i) for (int i = 0; i < 8; ++i)
@ -87,6 +97,7 @@ void readData() {
} }
} }
// Read RW_PIN state and set the busMode (aruduino related PINS) to OUTPUT or INPUT
void handleRWState() { void handleRWState() {
int tmp_rw_state=digitalRead(RW_PIN); int tmp_rw_state=digitalRead(RW_PIN);
@ -255,6 +266,14 @@ void loadPROG() {
void setup() { void setup() {
pinMode(CLOCK_PIN, OUTPUT); pinMode(CLOCK_PIN, OUTPUT);
pinMode(RW_PIN, INPUT); pinMode(RW_PIN, INPUT);
pinMode(RW_PIN, INPUT);
// You can remove the PIN input here and just set CLOCK_DELAY as const
// Remove also the analogRead on CLOCK_DELAY_PIN in step() below.
pinMode(CLOCK_DELAY_PIN, INPUT);
CLOCK_DELAY=analogRead(CLOCK_DELAY_PIN);
// End of remove
setupAddressPins(); setupAddressPins();
setBusMode(OUTPUT); setBusMode(OUTPUT);
@ -273,6 +292,8 @@ void setup() {
Serial.print("ERAM: "); Serial.print("ERAM: ");
Serial.print(sizeof(RAM_BANK_2)); Serial.print(sizeof(RAM_BANK_2));
Serial.println(" BYTE"); Serial.println(" BYTE");
Serial.print("CLOCK DELAY: ");
Serial.println(CLOCK_DELAY);
loadBASIC(); loadBASIC();
loadPROG(); loadPROG();
@ -294,17 +315,25 @@ void handleClock() {
} }
void handleBusRW() { void handleBusRW() {
// READ OR WRITE TO BUS?
// If nothing changed from the last cycle, we don't need to upadte anything
if (pre_address != address || pre_rw_state != rw_state) { if (pre_address != address || pre_rw_state != rw_state) {
// READ OR WRITE TO BUS?
rw_state ? writeToDataBus() : readFromDataBus(); rw_state ? writeToDataBus() : readFromDataBus();
pre_address = address; pre_address = address;
pre_rw_state = rw_state; pre_rw_state = rw_state;
} }
} }
void loop () { void step() {
CLOCK_DELAY=analogRead(CLOCK_DELAY_PIN); // Can be removed, see setup()
handleClock(); handleClock();
readAddress(); readAddress();
handleBusRW(); handleBusRW();
handleKeyboard(); handleKeyboard();
} }
void loop () {
step();
}