; time synchronisation
wait movf TMR0,W ; get timer 4MHz/4cy/32 = 32us
xorlw .125 ; compare with 125 x 32us = 4ms
btfss STATUS,Z ; if not equal
goto wait ; then continue waiting
; If TMR0 register is written, the increment is inhibited for the
; following two cycles. The user can work around this by writing
; an adjusted value to the TMR0 register.
; increment 4ms counter
movlw 8 ; advance 8x32us to allow for TMR0 reset
movwf TMR0 ; reset TMR0 with adjusted value
incf CNT1 ; increment 4ms timer
; check for clock set
clkset btfss CNT1,5 ; check every time bit 5 goes hi
goto incsec ; if not set goto incsec
movf PORTB,W ; Get input from PORTB
andlw b'001000' ; Line high?
btfss STATUS,Z ; If not -- active low
goto incsec ; got incsec
incf MINUTE ; increment minute
clrf SECOND ; reset seconds to zero
clrf CNT1 ; clear 4ms counter
goto lomin ; go check the minutes
; increment seconds
incsec movf CNT1,W ; get 4ms counter
xorlw .250 ; compare with 250
btfss STATUS,Z ; if not equal
goto check ; goto check
incf SECOND ; else increment second
clrf CNT1 ; reset 8ms timer
; check time
check movf SECOND,W ; get seconds.
xorlw .60 ; compare with 60.
btfss STATUS,Z ; if not
goto lomin ; goto lomin,
incf MINUTE ; else increment minutes.
clrf SECOND ; clear seconds.
;work out new time
lomin
include "p16f505.inc" ;
__config _IntRC_OSC_CLKOUTEN
org 000
loop nop
goto loop
end
; include file with config bit definitions include "p16f505.inc" ; ; config - enable internal OSC and allow use of RB4 ; - disable MCLRE and allow use of RB3 (input only) ; - disable Watchdog Timer, we don't use it. __config _IntRC_OSC_RB4EN & _MCLRE_OFF & _WDT_OFF ; local regsiters INB equ 0x08 INC equ 0x09
INPUT equ 0x0A
OUTB equ 0x0B OUTC equ 0x0C PWRSTS equ 0x0D
SEGDATA equ 0x10 SEG0 equ 0x10 SEG1 equ 0x11 SEG2 equ 0x12 SEG3 equ 0x13 SEG4 equ 0x14 SEG5 equ 0x15 SEG6 equ 0x16 SEG7 equ 0x17 SEG8 equ 0x18 SEG9 equ 0x19 SEGA equ 0x1A SEGB equ 0x1B SEGC equ 0x1C SEGD equ 0x1D SEGE equ 0x1E SEGF equ 0x1F ; start here org 000 movf STATUS,PWRSTS ; Save Power on status ; Port configuration ; a ; +-----+ --- ; VCC [| |] GND f| g |b ; D3 --> RB5 [| |] RB0 --> a --- ; D2 --> RB4 [| PIC |] RB1 --> b e| |c ; D1 --> RB3 [| 16F |] RB2 --> c --- ; D0 --> RC5 [| 505 |] RC0 --> d d ; NC RC4 [| |] RC1 --> e ; g <-- RC3 [| |] RC2 --> f ; +-----+ ; ; RRRRRR ; BBBBBB ; 543210 init movlw b'111000' ; Set PORTB Pins tris PORTB ; RRRRRR ; CCCCCC ; 543210 movlw b'100000' ; Set PORTC Pins tris PORTC ; Load Segment values into memory. ;Digit gfedcba abcdefg a b c d e f g ;0 0x3F 0x7E on on on on on on off ;1 0x06 0x30 off on on off off off off ;2 0x5B 0x6D on on off on on off on ;3 0x4F 0x79 on on on on off off on ;4 0x66 0x33 off on on off off on on ;5 0x6D 0x5B on off on on off on on ;6 0x7D 0x5F on off on on on on on ;7 0x07 0x70 on on on off off off off ;8 0x7F 0x7F on on on on on on on ;9 0x6F 0x7B on on on on off on on ;A 0x77 0x77 on on on off on on on ;b 0x7C 0x1F off off on on on on on ;C 0x39 0x4E on off off on on on off ;d 0x5E 0x3D off on on on on off on ;E 0x79 0x4F on off off on on on on ;F 0x71 0x47 on off off off on on on movlw 0x3F movwf SEG0 movlw 0x06 movwf SEG1 movlw 0x5B movwf SEG2 movlw 0x4F movwf SEG3 movlw 0x66 movwf SEG4 movlw 0x6D movwf SEG5 movlw 0x7D movwf SEG6 movlw 0x07 movwf SEG7 movlw 0x7F movwf SEG8 movlw 0x6F movwf SEG9 movlw 0x77 movwf SEGA movlw 0x7C movwf SEGB movlw 0x39 movwf SEGC movlw 0x5E movwf SEGD movlw 0x79 movwf SEGE movlw 0x71 movwf SEGF ; End of initialisation ; To here 37 Instructions @ 4MHz = 37uS ; Main Program Starts here. poweron clrf OUTB ; Clear output Register B clrf OUTC ; Clear output Register C btfss PWRSTS,RBWUF; Check Power-On Status goto display ; blank if power on ; Reset output values and indexes loop clrf OUTB ; Clear output Register B clrf OUTC ; Clear output Register C movlw SEGDATA ; Load W with SEG DATA base movwf FSR ; Save to FSR ; read value from PORTs movf PORTB,W ; Read PORTB
movwf INB ; Save PORTB
movf PORTC,W ; Read PORTC movwf INC ; Save PORTC ; combine port reads into a nibble in W register clrf INPUT ; Clear INPUT register btfsc INB,RB5 ; Test RB5 (D3) bsf INPUT,3 ; Set D0
btfsc INB,RB4 ; Test RB4 (D2) bsf INPUT,2 ; Set D1 btfsc INB,RB3 ; Test RB3 (D1) bsf INPUT,1 ; Set D2 btfsc INC,RC5 ; Test RC5 (D0) bsf INPUT,0 ; Set D3 movf INPUT,W ; Move value to W ; add value to index register and fetch segment value addwf FSR,F ; Add index to FSR pointer ; prepare register output bits btfsc INDF,0 ; Test for 'a' segment bsf OUTB,RB0 ; Set 'a' segment btfsc INDF,1 ; Test for 'b' segment bsf OUTB,RB1 ; Set 'b' segment btfsc INDF,2 ; Test for 'c' segment bsf OUTB,RB2 ; Set 'c' segment btfsc INDF,3 ; Test for 'd' segment bsf OUTC,RC0 ; Set 'd' segment btfsc INDF,4 ; Test for 'e' segment bsf OUTC,RB1 ; Set 'e' segment btfsc INDF,5 ; Test for 'f' segment bsf OUTC,RB2 ; Set 'f' segment btfsc INDF,6 ; Test for 'g' segment bsf OUTC,RB3 ; Set 'g' segment ; move output to ports display movf OUTB,W ; Get values to send to PORTB movwf PORTB ; Send to PORTB movf OUTC,W ; Get values to send to PORTC movwf PORTC ; Send to PORTC ; around again goto loop ; go back to loop - 50uS loop end
od -Ax -t x1 zx81.rom
#includemain() { int c,sum; sum=0; while ((c=getchar()) != EOF) { sum=sum+c; } printf("Checksum: %d\n",sum); }
#!/bin/bash
split -C 64 ${1} ${1}.part.
for part in `ls ${1}.part.*`
do
cat ${part} >> ${2}
sleep 1
done
rm -f ${1}.part.*
./eeprom_send.sh zx81.rom /dev/ttyACM0
/*
EEPROM Programmer
*/
#define memsize 8192
int STS = 13; // Status Indicator
int AP[16] = {22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52};
int AD[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
int DP[8] = {23,25,27,29,31,33,35,37};
int DD[8] = {0,0,0,0,0,0,0,0};
int CE = 4;
int OE = 3;
int WE = 2;
int i;
int A;
int D;
int wait;
void setup() {
Serial.begin(115200);
Serial.flush();
pinMode(STS, OUTPUT);
// Setup Address Pins
for (i=0;i<16;i++) {
pinMode(AP[i],OUTPUT);
}
// Setup Data Pins
for (i=0;i<8;i++) {
pinMode(DP[i],OUTPUT);
}
// Setup Control Pins
pinMode(CE, OUTPUT);
pinMode(WE, OUTPUT);
pinMode(OE, OUTPUT);
// Setup Chip
digitalWrite(CE, LOW);
digitalWrite(WE, LOW);
digitalWrite(OE, HIGH);
Serial.println("Waiting for Data...");
while(Serial.available()==0) {
digitalWrite(STS,LOW);
delay(100);
digitalWrite(STS,HIGH);
delay(100);
}
for (A=0;A<memsize;A++) {
D=Serial.read();
digitalWrite(STS,HIGH); //Signal that we're writing.
// Setup Address Pins
for (i=0;i<16;i++) {
if((A&bit(i))>0) {
AD[i]=HIGH;
} else {
AD[i]=LOW;
}
digitalWrite(AP[i],AD[i]);
}
delay(1);
digitalWrite(OE,LOW); // Reads Disabled
delay(1);
digitalWrite(CE,HIGH); // Chip Enable
delay(1);
digitalWrite(WE,HIGH); // Write Enabled
delay(1);
// Setup Data Pins
for (i=0;i<8;i++) {
if((D&bit(i))>0) {
DD[i]=HIGH;
} else {
DD[i]=LOW;
}
digitalWrite(DP[i],DD[i]);
}
delay(1);
digitalWrite(WE,LOW); // Write Disabled
delay(1);
digitalWrite(CE,LOW); // Chip Disabled
delay(1);
digitalWrite(OE,HIGH); // Reads Enabled
delay(1);
digitalWrite(STS,LOW); // Signal that we're waiting
wait=0;
while(Serial.available()==0) {
delay(1);
if (wait>2000) {
A=memsize;
break;
}
wait++;
}
}
}
void loop() {
digitalWrite(STS, HIGH); // set the LED on
delay(1000); // wait for a second
digitalWrite(STS, LOW); // set the LED off
delay(1000); // wait for a second
}
Please note that I have disabled comments on this post purely due to a persistent spammer - Dave 23/04/2021.
Its all very well having an EEPROM chip to store our program for the Z80, but somehow we need to get the code onto it. Enter, the EEPROM programmer. So far I have wired up the EEPROM to the Arduino Mega and I can read from it successfully. Writing to it is easy enough, but just now I can't bulk load a file to it. When I do, go find Part 2 :)
/*
EEPROM Chip Reader
*/
#define memsize 8192
int STS = 13; // Status Indicator
int AP[16] = {22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52};
int AD[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
int DP[8] = {23,25,27,29,31,33,35,37};
int DD[8] = {0,0,0,0,0,0,0,0};
int CE = 4;
int OE = 3;
int WE = 2;
int i;
int j;
int D;
int A;
void setup() {
// Setup Control Pins
pinMode(CE, OUTPUT);
pinMode(WE, OUTPUT);
pinMode(OE, OUTPUT);
// Disable Chip, and disable read and write.
digitalWrite(CE, LOW);
digitalWrite(WE, LOW);
digitalWrite(OE, LOW);
Serial.begin(115200);
Serial.println("Reading EEPROM...");
pinMode(STS, OUTPUT);
digitalWrite(STS,HIGH);
// Setup Address Pins
for (i=0;i<16;i++) {
pinMode(AP[i],OUTPUT);
}
// Setup Data Pins
for (i=0;i<8;i++) {
pinMode(DP[i],INPUT);
}
delay(1000);
for (A=0;A<memsize;) {
if (A<4096) Serial.print("0");
if (A<256) Serial.print("0");
if (A<16) Serial.print("0");
Serial.print(A,HEX);
Serial.print(" ");
for (j=0;j<16;j++) {
// Setup Address Pins
for (i=0;i<16;i++) {
if((A&bit(i))>0) {
AD[i]=HIGH;
} else {
AD[i]=LOW;
}
digitalWrite(AP[i],AD[i]);
}
digitalWrite(CE,HIGH); // Chip Enabled
digitalWrite(OE,HIGH); // Read Enabled
// Read Data Pins
D=0;
for (i=0;i<8;i++) {
DD[i]=digitalRead(DP[i]);
D=D+bit(i)*DD[i];
}
digitalWrite(OE,LOW); // Read Disabled
digitalWrite(CE,LOW); // Chip Disabled
if (D<16) Serial.print("0");
Serial.print(D,HEX);
Serial.print(" ");
A++;
}
Serial.println();
}
}
void loop() {
digitalWrite(STS, HIGH); // set the LED on
delay(500); // wait for a second
digitalWrite(STS, LOW); // set the LED off
delay(500); // wait for a second
}
sudo apt-get install -y lrzsz
convert -negate a.bmp b.bmpand hey presto:
LD A,1 ; Load A with 1 LD B,2 ; Load B with 2 ADD A,B ; Add B to A HALT ; Stop
3E 01 ; Load A with 1 06 02 ; Load B with 2 80 ; Add B to A 76 ; StopNow as you can see the program was easier to understand than the 6 bytes that the Z80 needs to receive to make it happen. What we need is something that will assemble the bytes from the written commands. As it happens there is a Z80 Assembler program called z80asm which will do it for you. So this is what I am going to use to create the bytes that I will store in the EEPROM to instruct the Z80 what to do.
/*
Zilog Z80 Controller
*/
const int CPU = 0;
const int PIN = 1;
const int DIR = 2;
const int STS = 3;
/* low states = true */
int CLK[4] = {06,13,OUTPUT,LOW}; // in
int INT[4] = {16,0,OUTPUT,LOW}; // in
int NMI[4] = {17,0,OUTPUT,LOW}; // in
int HALT[4] = {18,12,INPUT,LOW}; // out
int MREQ[4] = {19,11,INPUT,LOW}; // out
int IORQ[4] = {20,10,INPUT,LOW}; // out
int RD[4] = {21,9,INPUT,LOW}; // out
int WR[4] = {22,8,INPUT,LOW}; // out
int BUSACK[4] = {23,7,INPUT,LOW}; // out
int WAIT[4] = {24,0,OUTPUT,LOW}; // in
int BUSRQ[4] = {25,0,OUTPUT,LOW}; // in
int RESET[4] = {26,6,OUTPUT,LOW}; // in
int M1[4] = {27,5,INPUT,LOW}; // out
int RFSH[4] = {28,4,INPUT,LOW}; // out
int OLDM1[4] = {27,5,INPUT,LOW};
int T = 0;
void setup() {
// Define Pins
pinMode(CLK[PIN], CLK[DIR]);
pinMode(M1[PIN], M1[DIR]);
pinMode(RESET[PIN], RESET[DIR]);
pinMode(HALT[PIN], HALT[DIR]);
pinMode(MREQ[PIN], MREQ[DIR]);
pinMode(IORQ[PIN], IORQ[DIR]);
pinMode(RD[PIN], RD[DIR]);
pinMode(WR[PIN], WR[DIR]);
pinMode(BUSACK[PIN], BUSACK[DIR]);
pinMode(RFSH[PIN], RFSH[DIR]);
// Setup Serial Port
Serial.begin(9600);
// Reset CPU
Serial.println("CPU Reset");
delay(500);
RESET[STS]=HIGH;
digitalWrite(RESET[PIN],RESET[STS]);
delay(2000);
RESET[STS]=LOW;
digitalWrite(RESET[PIN],RESET[STS]);
}
void loop() {
//Start Clock Period T
digitalWrite(CLK[PIN],CLK[STS]);
delay(500);
// Read Machine Cycle Status M Clock High
M1[STS]=digitalRead(M1[PIN]);
HALT[STS]=digitalRead(HALT[PIN]);
MREQ[STS]=digitalRead(MREQ[PIN]);
IORQ[STS]=digitalRead(IORQ[PIN]);
RD[STS]=digitalRead(RD[PIN]);
WR[STS]=digitalRead(WR[PIN]);
BUSACK[STS]=digitalRead(BUSACK[PIN]);
RFSH[STS]=digitalRead(RFSH[PIN]);
Serial.print(T);
Serial.print("=");
Serial.print(CLK[STS]);
Serial.print(" M1=");
Serial.print(M1[STS]);
Serial.print(" HALT=");
Serial.print(HALT[STS]);
Serial.print(" MREQ=");
Serial.print(MREQ[STS]);
Serial.print(" IORQ=");
Serial.print(IORQ[STS]);
Serial.print(" RD=");
Serial.print(RD[STS]);
Serial.print(" WR=");
Serial.print(WR[STS]);
Serial.print(" RFSH=");
Serial.print(RFSH[STS]);
Serial.print(" BUSACK=");
Serial.print(BUSACK[STS]);
Serial.println();
if(M1[STS]==HIGH && OLDM1[STS]==LOW) {
Serial.println("----M1 Starts----");
}
OLDM1[STS]=M1[STS];
CLK[STS]=!CLK[STS];
T=T+CLK[STS];
}
Basically on each chip you can stick in a high voltage and get a low voltage out and visa versa. One pin goes in, one comes out and there are 6 pairs (hence the Hex). Now the Z80 has 13 control pins and so I opted to get 2 Hex Inverters. Ok so that lets me control 12 pins on the Z80, so I will just hook up any pins I don't really need to use at this stage to the +5V supply (remember high voltage means OFF).