Automatic recognition of memory capacity of P2000T

ifilot · Jul 15, 2023 · 4f56609 · 4f56609
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -0,0 +1,51 @@
+# Change Log
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+## [0.2.0] - 2023-07-15
+
+### Added
+
+- Reading memory capacity of P2000T in source code and using that to automatically
+  determine the top part of RAM for transfer over RS232.
+
+### Changed
+
+### Fixed
+
+- Fixed error in memory address for the BASIC code for 32kb machines in the 
+  README.md
+
+## [0.1.3] - 2023-07-14
+
+### Added
+
+- Added instruction message on screen when executing `?USR1(0)`
+- Adding software LICENSE
+
+### Changed
+
+### Fixed
+
+## [0.1.2] - 2023-07-14
+
+### Added
+
+- Automatic compilation of ROM binary in release procedure
+
+### Changed
+
+### Fixed
+
+## [0.1.1] - 2023-07-14
+
+### Added
+
+- Expanded upon documentation
+- Adding CI/CD procecure
+
+### Changed
+
+### Fixed
diff --git a/Makefile b/Makefile
@@ -3,7 +3,7 @@ all: src/BASIC-MODIFIED.bin
 src/ollie.bin: src/ollie.asm
 	z80asm src/ollie.asm -o src/ollie.bin
 
-src/BASIC-MODIFIED.bin: src/ollie.bin
+src/BASIC-MODIFIED.bin: src/ollie.bin src/build.py
 	python3 src/build.py
 
 clean:

diff --git a/README.md b/README.md
@@ -21,11 +21,11 @@ After booting the P2000T with the modified BASIC-NL image, run
 
 ```basic
 10 CLEAR 50,&H9DFF
-20 DEF USR1=&H4EC7
+20 DEF USR1=&H4EEE
 ```
 
 > **Note**: Use `&H9DFF` in the above instructions if your P2000T has 16kb of memory. 
-> If your P2000T has 32kb or 48kb of memory, use `&HBDFF` or `&HDDFF`, respectively.
+> If your P2000T has 32kb or 48kb of memory, use `&HDDFF` or `&HFDFF`, respectively.
 > Alternatively, you can also use the following one-liner to let the P2000T
 > figure it out for you: `10 CLEAR 50,&H9DFF+256*32*(PEEK(&H605C)+PEEK(&H605C)=1))`.
 

diff --git a/src/build.py b/src/build.py
@@ -3,11 +3,15 @@
 import numpy as np
 import os
 import subprocess
+import hashlib
 
 # set root path
 ROOT = os.path.dirname(__file__)
+START = 0x3EC7 # start position on ROM
 
 def main():
+    print('Building ROM...\n')
+
     # open standard BASIC rom
     f = open(os.path.join(ROOT, 'BASICROM.BIN'), 'rb')
     rom = bytearray(f.read())
@@ -33,13 +37,25 @@ def main():
     f = open(os.path.join(ROOT, 'ollie.bin'), 'rb')
     ollie = bytearray(f.read())
     f.close()
-    rom[0x3EC7:0x3EC7+len(ollie)] = ollie
+    rom[START:START+len(ollie)] = ollie
     print("Inserting code; using %i / %i bytes of free space" % 
-          (len(ollie),0x4000-0x3EC7))
+          (len(ollie),0x4000-START))
 
-    f = open(os.path.join(ROOT, 'BASIC-MODIFIED.bin'), 'wb')
+    # verify that the byte at 0x3EEE corresponds to the opt code for ld hl
+    print('Checking opt code at 0x3EEE=0x%02X ?= 0x21 (%s)' % 
+        (rom[0x3EEE], 'true' if rom[0x3EEE]==0x21 else 'false'))
+    assert(rom[0x3EEE]==0x21)
+
+    # store file
+    filename = os.path.join(ROOT, 'BASIC-MODIFIED.bin')
+    f = open(filename, 'wb')
     f.write(rom)
     f.close()
+
+    # generate checksum
+    print()
+    print('Done writing modified ROM.')
+    print('Checksum: %s' % hashlib.md5(open(filename, 'rb').read()).hexdigest())
 
 if __name__ == '__main__':
     main()
diff --git a/src/ollie.asm b/src/ollie.asm
@@ -1,44 +1,52 @@
 ;-------------------------------------------------------------------------------
-; This code is largely based on the source code as developed by
+; This code is based on the source code as developed by
 ; dionoid(https://github.com/dionoid) as found via the link below:
 ; https://github.com/p2000t/software/blob/master/utilities/pc2p2000t/pc2p2000t.z80.asm
 ;-------------------------------------------------------------------------------
-BasicProgStart:    EQU    $6547
-ProgramBlocks:     EQU    $9f4f ; byte
-ProgramLength:     EQU    $9f34 ; word
+basic_start_addr:    EQU    $6547
 
     org $4ec7
 
+pageaddr:
+    DB $9f,$df,$ff ; set page address positions (upper byte)
+
+; exactly 27 bytes of data should be placed here such that the starting
+; instruction is at $4eee; this allows for an easy BASIC command of
+; `20 DEF USR1=&H4EEE`
+
+    ; dummy data (36 bytes)
+    DB $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
+    DB $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
+    DB $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
+
 start:
     ld hl,.line1
     ld de,$5000+20*$50
     call printstring
     ld hl,.line2
     ld de,$5000+21*$50
     call printstring
-    ld hl,.line3
-    ld de,$5000+22*$50
-    call printstring
     jp read_program
 
-.line1: DB "P2000T IS IN LISTENING MODE",255
-.line2: DB "COPY FILE OVER RS232",255
-.line3: DB "BAUD=9600, PARITY=N, DATA=8, STOP=1",255
+.line1: DB "P2000T READY TO COPY FILE OVER RS232",255
+.line2: DB "BAUD=9600, PARITY=N, DATA=8, STOP=1",255
 
+;-------------------------------------------------------------------------------
 ; reads a byte from the serial port (9600 baud) and returns in A
+;-------------------------------------------------------------------------------
 read_byte:
-    push bc                 ; C5 [11]
+    push bc
 check_start_bit:
-    in a,($20)              ; DB 20 [11]
-    and $01                 ; E6 01 [7] - check if bit D0 is 0
-    jr nz, check_start_bit  ; 20 FA [7] 
-    ld b, $15               ; 06 15 [7]
+    in a,($20)
+    and $01                 ; check if bit D0 is 0
+    jr nz, check_start_bit
+    ld b, $15
 delay_on_start_bit:
-    djnz delay_on_start_bit ; 10 FE [13/8]
-    ld b, $08               ; 06 08 [7]
+    djnz delay_on_start_bit
+    ld b, $08
 
 read_next_bit:
-    in a,($20)              ; DB 20 [11]
+    in a,($20)
 
     ; 58 clocks without extra delay
     ; 1.2 * 1041.67 = 1250. Need delay in B: 
@@ -50,78 +58,109 @@ read_next_bit:
     ; 9600 baud: 1.2 * 260.42 = 312.5
     ; delay in B: (312.5 - 58) / 13 = 19.6 + 1 = 21 (&h15)
 
-    rra                     ; 1F [4] - bit 0 into carry
-    rr c                    ; CB 19 [8]
-    push bc                 ; C5 [11]
-    ld b, $10               ; 06 10 [7]
+    rra                     ; bit 0 into carry
+    rr c
+    push bc
+    ld b, $10
 delay_bit:
-    djnz delay_bit          ; 10 FE [13/8]
-    pop bc                  ; C1 [10]
-    djnz read_next_bit      ; 10 F3 [13]
+    djnz delay_bit
+    pop bc
+    djnz read_next_bit
 
     ; 72 clocks without extra delay. So delay in B: 
     ; 2400 baud: (1041.67 - 72) / 13 = 74.6 + 1 = 76 (&h4C)
     ; 4800 baud: (520.84 - 72) / 13 = 34.53 + 1 = 35 (&h23)
     ; 9600 baud: (260.42 - 72) / 13 = 14.49 + 1 = 16 (&h10)
 
-    ld a,c                  ; 79 [4]
-    pop bc                  ; C1 [10]
-    ret                     ; C9 [10]
+    ld a,c
+    pop bc
+    ret
 
+;-------------------------------------------------------------------------------
+; read a program over the RS232 port
+;-------------------------------------------------------------------------------
 read_program:               ; start the program
-    di                      ; F3 - disable interrupts
+    di                      ; disable interrupts
 
-read_header:                ; read 256-byte header into $9f00 - $9fff
-    ld b,0                  ; 06 00
-    ld hl, $9f00            ; 21 00 9F
+read_header:                ; read 256-byte header into top of memory
+    call setpage
+    ld l,0
+    ld b,0
 read_header_loop:
-    call read_byte          ; CD 00 9E
-    ld (hl),a               ; 77
-    inc hl                  ; 23
-    djnz read_header_loop   ; 10 F9
+    call read_byte
+    ld (hl),a
+    inc hl
+    djnz read_header_loop
 
     ;read the blocks and put into basic memory
-    ld hl, ProgramBlocks    ; 21 4F 9F
-    ld c, (hl)              ; 4E - load number of blocks into C
-    ld hl, BasicProgStart   ; 21 47 65 - IDEA: read pointer from $625c?
-    jr read_block           ; 18 07 - first header already read, so skip
+    push bc
+    call setpage
+    pop bc
+    ld l,$4f                ; set pointer to address containing number of blocks
+    ld c, (hl)              ; load number of blocks into c
+    ld hl, basic_start_addr   ; ?read pointer from $625c?
+    jr read_block           ; first header already read, so skip
 ignore_header:
-    ld b, $00               ; 06 00 - ignore later 256-byte headers
+    ld b, $00               ; ignore later 256-byte headers
 ignore_header_loop:
-    call read_byte          ; CD 00 9E
-    djnz ignore_header_loop ; 10 FB
+    call read_byte
+    djnz ignore_header_loop
 read_block:
-    ld de, $400             ; 11 00 04
+    ld de, $400
 read_block_loop:
-    call read_byte          ; CD 00 9E
-    ld (hl),a               ; 77
-    inc hl                  ; 23
-    dec de                  ; 1B
-    ld a,d                  ; 7A
-    or e                    ; B3
-    jr nz, read_block_loop  ; 20 F6
-    dec c                   ; 0D
-    jr nz, ignore_header    ; 20 E9
-
-    ld de, BasicProgStart   ; 11 47 65 
-    ld hl, (ProgramLength)  ; 2A 34 9F
-    add hl,de               ; 19
-    ld ($6405), hl          ; 22 05 64 - set basic pointers to var space
-    ld ($6407), hl          ; 22 07 64
-    ld ($6409), hl          ; 22 09 64
+    call read_byte
+    ld (hl),a
+    inc hl
+    dec de
+    ld a,d
+    or e
+    jr nz, read_block_loop
+    dec c
+    jr nz, ignore_header
+
+    ld de, basic_start_addr ; set de to start of basic program
+    call setpage            ; set page in h
+    ld l,$34
+    ld c,(hl)               ; load lower byte program length
+    inc hl                  ; increment pointer
+    ld b,(hl)               ; lower upper byte program length
+    ld a,b                  ; copy b->a->h
+    ld h,a
+    ld a,c                  ; copy c->a->l
+    ld l,a
+    add hl,de
+    ld ($6405), hl          ; set basic pointers to var space
+    ld ($6407), hl
+    ld ($6409), hl
 
     ; reset the pointers to end of memory for BASIC
-    ld a, ($63b9)           ; 3A B9 63
-    add a, 2                ; C6 02
-    ld ($63b9), a           ; 32 B9 63
-    ld ($6259), a           ; 32 59 62
+    ld a, ($63b9)
+    add a, 2
+    ld ($63b9), a
+    ld ($6259), a
 
     ; succes: play beep
-    ld a,$07                ; 3E 07
-    call $104a              ; CD 4A 10
+    ld a,$07
+    call $104a
 
-    ei                      ; FB - enable interrupts
-    ret                     ; C9
+    ei                      ; enable interrupts
+    ret
+
+;-------------------------------------------------------------------------------
+; set the page to which the header data is written in h
+; output: hl - start of buffer area
+;   uses: a,bc
+;-------------------------------------------------------------------------------
+setpage:
+    ld bc,pageaddr         ; set pointer to page addresses
+    ld a,($605c)           ; read RAM value, 1->16kb,2->32kb,3->48kb
+    dec a                  ; decrement such that index starts at 0
+    add a,c                ; add lower byte of page addr to it
+    ld c,a                 ; update lower byte page address pointer
+    ld a,(bc)              ; load page byte into a
+    ld h,a                 ; set upper byte into h
+    ld l,$00               ; set lower byte to 0
+    ret
 
 ;-------------------------------------------------------------------------------
 ; print string to screen