read buffer & last operation

address_decoder.jed

@@ -2,7 +2,7 @@
 GAL20V8
 EQN2JED - Boolean Equations to JEDEC file assembler (Version V101)
 Copyright (c) National Semiconductor Corporation 1990-1993
-Assembled from "e:/APPLE1~1/ADDRES~1.EQN". Date: 5-24-120
+Assembled from "c:/APPLE1~1/ADDRES~1.EQN". Date: 6-7-120
 *
 NOTE PINS RW:2 A0:3 A1:4 A2:5 A3:6 A4:7 A5:8 A6:9 A7:10 A8:11*
 NOTE PINS GND:12 A9:14 A10:15 A11:16 SR:17 RD:18 WD:19 ROM:20*
@@ -19,7 +19,7 @@ L0640
 L0960
 1011011010011011101110111010101001101011*
 L1280
-0111101010011011101110111010101001101011*
+0111101010111011101110111010101001101011*
 L1600
 0111101010111011101110111010101010101011*
 L2560
@@ -30,5 +30,5 @@ L2640
 0000000010000000111100001000000010000000100000000000000000000000*
 L2704
 10*
-C1FC0*
+C1FC4*
 0000

addressdecoder.eqn

@@ -7,7 +7,7 @@ R=23 VCC=24
 equations
 
 SR = /A0 * /A1 * /A2 * /A3 * /A4 * /A5 * /A6 * /A7 * /A8 * /A9 * /A10 * /A11 * /R * RW
-RD = /A0 * /A1 * /A2 * /A3 * /A4 * /A5 * /A6 * A7 * /A8 * /A9 * /A10 * /A11 * /R * RW * PHI
+RD = /A0 * /A1 * /A2 * /A3 * /A4 * /A5 * /A6 * A7 * /A8 * /A9 * /A10 * /A11 * /R * RW
 WD = A0 * /A1 * /A2 * /A3 * /A4 * /A5 * /A6 * A7 * /A8 * /A9 * /A10 * /A11 * /R * /RW * PHI
 /ROM = A8 * /R * RW
     + A9 * /R * RW

firmware/main.c

@@ -21,6 +21,8 @@
 #define DATA6 PD3
 #define DATA7 PD4
 
+#define BUFFER_SIZE 8
+
 typedef enum {NONE, READ, WRITE} mode_t;
 mode_t mode = NONE;
 
@@ -31,6 +33,10 @@ uint8_t lower_part = 0x00;
 uint8_t data_write_interrupt_count = 0;
 uint8_t data_read_interrupt_count = 0;
 
+// receive buffer
+uint8_t receive_buffer[BUFFER_SIZE];
+int8_t receive_index = -1;
+
 // Registers: PCMSK0, PCMSK1, PCMSK2 :registers that enable or disable pin-change interrupts
 // on individual pins
 
@@ -46,6 +52,14 @@ inline void not_ready() {
     PORTD &= ~(_BV(STATUS));
 }
 
+inline void put_data() {
+    upper_part = (PORTD & 0xe3) | ((0xe0 & receive_buffer[0])>>3);
+    lower_part = (PORTB & 0xc1) | ((0x1f & receive_buffer[0])<<1);
+    
+    PORTD = upper_part;
+    PORTB = lower_part;
+}
+
 void setup() {
 
     // set input on DATA_READ_LINE
@@ -94,9 +108,28 @@ ISR(PCINT0_vect) {
             // set output on data pins
             DDRD |= _BV(DATA5) | _BV(DATA6) | _BV(DATA7);
             DDRB |= _BV(DATA0) | _BV(DATA1) | _BV(DATA2) | _BV(DATA3) | _BV(DATA4);
-        }
+            
+            receive_index = -1;
             not_ready();
             data_read_interrupt_count = 1;
+            return;
+        }
+        
+        if (receive_index > -1) {
+            uint8_t i;
+            for (i = 1; i <= receive_index; i++) {
+                receive_buffer[i - 1] = receive_buffer[i];
+            }
+            receive_index--;
+            
+            if (receive_index == -1) {
+                not_ready();
+            } else {
+                // put next byte from receive buffer
+                put_data();
+            }
+        }
+        data_read_interrupt_count = 1;
     } else {
         data_read_interrupt_count = 0;
     }
@@ -149,11 +182,14 @@ ISR(USART_RX_vect)
     if (mode == READ) {
         data = UDR0;
         
-        upper_part = (PORTD & 0xe3) | ((0xe0 & data)>>3);
-        lower_part = (PORTB & 0xc1) | ((0x1f & data)<<1);
+        if (receive_index >= BUFFER_SIZE - 1) {
+            receive_index = -1;
+        }
         
-        PORTD = upper_part;
-        PORTB = lower_part;
+        receive_buffer[++receive_index] = data;
+        
+        // always put first byte from receive buffer
+        put_data();
         
         ready();
     }
@@ -174,4 +210,3 @@ int main(void) {
     }
     return 0;   /* never reached */
 }
-

src/apple1serial.xa

@@ -1,10 +1,15 @@
  ;End address of dump block
-#define hex1_l $50
-#define hex1_h $51
+#define hex1_l $24
+#define hex1_h $25
 
 ;Begin address of dump block
-#define hex2_l $52
-#define hex2_h $53
+#define hex2_l $26
+#define hex2_h $27
+
+#define last_command $28
+#define last_command_none $00
+#define last_command_read $01
+#define last_command_write $02
 
 ;Input buffer
 #define input $0200
@@ -44,6 +49,8 @@ apple_serial
     jsr echo
     lda #CR             ;And drop the cursor one line
     jsr echo
+    lda #$00            ;Set last command type to NONE
+    sta last_command
     ldy #$FF            ;Reset the input buffer index
 
 next_char
@@ -133,28 +140,16 @@ separator
     sta hex1_h
     jmp next_chr
 
-reset
-    txa
-    pha
-    lda serial_reset
-    ldx #$00
-    ldy #$00
-reset_loop              ; ((2 + 2 + 3) * 255 + 2 + 3) * 255 =
-    nop                 ; 2 cycles
-    iny                 ; 2 cycles
-    bne reset_loop      ; 3 cycles
-    inx                 ; 2 cycles
-    bne reset_loop      ; 3 cycles
-    pla
-    tax
-    rts
-
 ;-------------------------------------------------------------------------
 ; Read procedure
 ;-------------------------------------------------------------------------
 
 read
+    lda last_command
+    cmp #last_command_read
+    beq read_ready
     lda serial_read     ;Enable read mode, this can be done quick, without reset
+read_ready
     ldy #$00
 
 read_byte
@@ -171,6 +166,8 @@ read_byte
     cmp hex1_h          ;Compare upper destination address half with upper end address half
     bne read_next       ;If not equal then proceed to read next byte
 
+    lda last_command_read ;Set last command to READ
+    sta last_command
     jmp next_cmd        ;Read is completed, proceed to next command
 
 read_next
@@ -187,10 +184,14 @@ read_next
 ;-------------------------------------------------------------------------
 
 write
+    lda last_command
+    cmp #last_command_write
+    beq write_ready
     jsr reset           ;Reset serial and give some time to stabilize
                         ;This is required due to inability to guess what is the current device mode
                         ;and prevents from polluting the output while setting the write mode
     sta serial_write    ;Enable write mode
+write_ready
     ldy #$00
 
 write_byte
@@ -207,6 +208,8 @@ write_byte
     cmp hex1_h          ;Compare upper source address half with upper end address half
     bne write_next      ;If not equal then proceed to write next byte
 
+    lda last_command_write ;Set last command to WRITE
+    sta last_command
     jmp next_cmd        ;Write is completed, proceed to next command
 
 write_next
@@ -222,6 +225,30 @@ write_next
 ; tool routines
 ;-------------------------------------------------------------------------
 
+reset
+    txa                 ;Preserve X on stack
+    pha
+
+    tya                 ;Preserve Y on stack
+    pha
+
+    lda serial_reset    ;Reset
+    ldx #$00
+    ldy #$00
+reset_loop              ; ~((2 + 2 + 3) * 255 + 2 + 3) * 255 =
+    nop                 ; 2 cycles
+    iny                 ; 2 cycles
+    bne reset_loop      ; 3 cycles
+    inx                 ; 2 cycles
+    bne reset_loop      ; 3 cycles
+
+    pla                 ;Restore Y from stack
+    tay
+
+    pla                 ;Restore X from stack
+    tax
+    rts
+
 increment_16bit
     inc $00,X
     bne increment_16bit_done

src/tests.xa

@@ -5,12 +5,12 @@
 #define serial_read  $C080
 #define serial_write $C081
 
-* = $C200
+* = $C300
 .dsb (*-end_of_apple1serial), 0
 
 ; teletype on apple-1
-* = $C200
-teletype_apple1 = $C200
+* = $C300
+teletype_apple1 = $C300
   lda serial_read
 wait
   lda serial_ready
@@ -20,16 +20,12 @@ wait
   jmp wait
 end_of_teletype_apple1
 
-; AD 80 C0 AD 00 C0 F0 FB
-; AD 80 C0 20 EF FF 4C 03
-; 00
-
 ; teletype on remote
-* = $C300
+* = $C400
 .dsb (*-end_of_teletype_apple1), 0
 
-* = $C300
-teletype_remote = $C300
+* = $C400
+teletype_remote = $C400
   lda #$FF
   sta serial_write
 get_key
@@ -42,16 +38,12 @@ get_key
   jmp get_key
 end_of_teletype_remote
 
-; A9 FF 8D 81 C0 AD 11 D0
-; 10 FB AD 10 D0 38 E9 A0
-; 8D 81 C0 4C 85 02
-
 ; 0-255 repeating counter over TXD
-* = $C400
+* = $C500
 .dsb (*-end_of_teletype_remote), 0
 
-* = $C400
-counter_remote = $C400
+* = $C500
+counter_remote = $C500
   ldy #$00
   sta serial_write
 check_ready
@@ -62,6 +54,3 @@ check_ready
   iny
   jmp check_ready
   
-; A0 00 8D 81 C0 AD 00 C0
-; F0 FB 98 8D 81 C0 C8 4C
-; 85 02