Over christmas thought I would get back into learning ZX81 assembly language and machine code. Am using Linux as my desktop, so am also using http://sz81.sourceforge.net/
Thought I would use the excellent updated version of Mastering Machine Code on the ZX81. Using an example from http://www.users.waitrose.com/~thunor// ... ter07.html
I was able to follow the updated book & using chapter07-hexld2.p I was able to get working a HELLO WORLD example seen below.
Code: Select all
OLD ROM NEW ROM
E1 E1 SPRINT POP HL
7E 7E LD A,(HL)
23 23 INC HL
E5 E5 PUSH HL
FEFF FEFF CP FF
C8 C8 RET Z
F5 PUSH AF <- OLD ROM ONLY
CDE006 CALL PRPOS <- OLD ROM ONLY
F1 POP AF <- OLD ROM ONLY
CD2007 CD0808 CALL PRINT
18EF 18F4 JR SPRINT
CD2B40 CD8240 CALL SPRINT
;OH WHAT A BEAUTIFUL MORNING; DEFM "HELLO WORLD"
FF FF DEFB FF
C9 C9 RET
Using this example from the book, thought it would be cool to try & get it working with pasmo. Here is my go at it using the mctemplate that comes with sz81
Code: Select all
; mctemplate - a Sinclair ZX81 machine code template
; Copyright (C) 2010 Thunor <thunorsif_at_hotmail.com>
;
; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
; =====================================================================
; mctemplate 0.1.3
;
; Tabs are set to 8.
;
; See mctemplate.txt for assembling instructions and information.
; =====================================================================
; Sinclair character codes.
_SPC equ 0x00 ; " "
_DQT equ 0x0b ; "
_PND equ 0x0c ; £
_DLR equ 0x0d ; $
_CLN equ 0x0e ; :
_QMK equ 0x0f ; ?
_OBR equ 0x10 ; (
_CBR equ 0x11 ; )
_GTH equ 0x12 ; >
_LTH equ 0x13 ; <
_EQU equ 0x14 ; =
_PLS equ 0x15 ; +
_MNS equ 0x16 ; -
_ASK equ 0x17 ; *
_SLS equ 0x18 ; /
_SMC equ 0x19 ; ;
_CMA equ 0x1a ; ,
_FST equ 0x1b ; .
_0 equ 0x1c
_1 equ 0x1d
_2 equ 0x1e
_3 equ 0x1f
_4 equ 0x20
_5 equ 0x21
_6 equ 0x22
_7 equ 0x23
_8 equ 0x24
_9 equ 0x25
_A equ 0x26
_B equ 0x27
_C equ 0x28
_D equ 0x29
_E equ 0x2a
_F equ 0x2b
_G equ 0x2c
_H equ 0x2d
_I equ 0x2e
_J equ 0x2f
_K equ 0x30
_L equ 0x31
_M equ 0x32
_N equ 0x33
_O equ 0x34
_P equ 0x35
_Q equ 0x36
_R equ 0x37
_S equ 0x38
_T equ 0x39
_U equ 0x3a
_V equ 0x3b
_W equ 0x3c
_X equ 0x3d
_Y equ 0x3e
_Z equ 0x3f
; Inverse equivalents of the above.
_SPCV equ _SPC+0x80 ; [ ]
_DQTV equ _DQT+0x80 ; ["]
_PNDV equ _PND+0x80 ; [£]
_DLRV equ _DLR+0x80 ; [$]
_CLNV equ _CLN+0x80 ; [:]
_QMKV equ _QMK+0x80 ; [?]
_OBRV equ _OBR+0x80 ; [(]
_CBRV equ _CBR+0x80 ; [)]
_GTHV equ _GTH+0x80 ; [>]
_LTHV equ _LTH+0x80 ; [<]
_EQUV equ _EQU+0x80 ; [=]
_PLSV equ _PLS+0x80 ; [+]
_MNSV equ _MNS+0x80 ; [-]
_ASKV equ _ASK+0x80 ; [*]
_SLSV equ _SLS+0x80 ; [/]
_SMCV equ _SMC+0x80 ; [;]
_CMAV equ _CMA+0x80 ; [,]
_FSTV equ _FST+0x80 ; [.]
_0V equ _0+0x80
_1V equ _1+0x80
_2V equ _2+0x80
_3V equ _3+0x80
_4V equ _4+0x80
_5V equ _5+0x80
_6V equ _6+0x80
_7V equ _7+0x80
_8V equ _8+0x80
_9V equ _9+0x80
_AV equ _A+0x80
_BV equ _B+0x80
_CV equ _C+0x80
_DV equ _D+0x80
_EV equ _E+0x80
_FV equ _F+0x80
_GV equ _G+0x80
_HV equ _H+0x80
_IV equ _I+0x80
_JV equ _J+0x80
_KV equ _K+0x80
_LV equ _L+0x80
_MV equ _M+0x80
_NV equ _N+0x80
_OV equ _O+0x80
_PV equ _P+0x80
_QV equ _Q+0x80
_RV equ _R+0x80
_SV equ _S+0x80
_TV equ _T+0x80
_UV equ _U+0x80
_VV equ _V+0x80
_WV equ _W+0x80
_XV equ _X+0x80
_YV equ _Y+0x80
_ZV equ _Z+0x80
_NL equ 0x76
_VAL equ 0xc5
_INT equ 0xcf
_USR equ 0xd4
_NOT equ 0xd7
_PWR equ 0xd8 ; **
_THEN equ 0xde
_STOP equ 0xe3
_REM equ 0xea
_LET equ 0xf1
_PRINT equ 0xf5
_RUN equ 0xf7
_SAVE equ 0xf8
_RAND equ 0xf9
_IF equ 0xfa
; RST routines (a selection of).
ERROR equ 0x08 ; Follow with a byte error code -1.
PRINT_CHAR equ 0x10 ; regA contains the char.
; ROM routines (a selection of).
KEYB_SCAN equ 0x02bb
KEYB_DECODE equ 0x07bd
; Start of the system variables area.
ERR_NR equ 0x4000
FLAGS equ 0x4001
ERR_SP equ 0x4002
RAMTOP equ 0x4004
MODE equ 0x4006
PPC equ 0x4007
p_start: org 0x4009
VERSN: defb 0
E_PPC: defw 20 ; BASIC line number of line with cursor.
D_FILE: defw display_file
DF_CC: defw display_file+1
VARS: defw variables
DEST: defw 0
E_LINE: defw edit_line
CH_ADD: defw p_end-1
X_PTR: defw 0
STKBOT: defw p_end
STKEND: defw p_end
BERG: defb 0
MEM: defw MEMBOT
SPARE1: defb 0
DF_SZ: defb 2 ; Number of lines in lower part of screen.
S_TOP: defw 10 ; BASIC line number of line at top of screen.
LAST_K: defw 0xffff
DB_ST: defb 0
MARGIN: defb 55 ; Blank lines above/below TV picture: US = 31, UK = 55.
NXTLIN: defw display_file ; Memory address of next program line to be executed.
OLDPPC: defw 0
FLAGX: defb 0
STRLEN: defw 0
T_ADDR: defw 0x0c8d
SEED: defw 0
FRAMES: defw 0 ; Updated once for every TV frame displayed.
COORDS: defw 0
PR_CC: defb 0xbc
S_POSN: defb 0x21,0x18
CDFLAG: defb 0x40
PRBUF: defs 0x20
defb _NL
MEMBOT: defs 0x1e
SPARE2: defw 0
; Start of the BASIC area for user programs.
basic_0001: defb 0,1 ; 1 REM
defw basic_0010-basic_0001-4
defb _REM
; Start of user machine code program
mem_16514:
;START ld a,_ASK
; call PRINT_CHAR
; jr START
SPRINT POP HL
LD A,(HL)
INC HL
PUSH HL
CP $FF
RET Z
CALL PRINT_CHAR
JR SPRINT
CALL SPRINT
; DEFM _O,_H,_SPC,_W,_H,_A,_T,_SPC,_A,_SPC,_B,_E,_A,_U,_T,_I,_F,_U,_L,_SPC,_M,_O,_R,_N,_I,_N,_G
DEFM _H,_E,_L,_L,_O,_SPC,_W,_O,_R,_L,_D
DEFB $FF
RET
; End of user machine code program ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
defb _NL
basic_0010: defb 0,10 ; 10 RAND VAL "USR 16514"
defw basic_0020-basic_0010-4
defb _RAND,_VAL,_DQT,_USR,_1,_6,_5,_1,_4,_DQT
defb _NL
basic_0020: defb 0,20 ; 20 REM ** TYPE RUN **
defw basic_end-basic_0020-4
defb _REM,_PWR,_SPC,_T,_Y,_P,_E,_RUN,_PWR
defb _NL
basic_end:
; Start of the display file (synonymous with video memory).
; Compressed for <= 3k RAM.
;display_file: defb _NL
; defb _NL,_NL,_NL,_NL,_NL,_NL,_NL,_NL
; defb _NL,_NL,_NL,_NL,_NL,_NL,_NL,_NL
; defb _NL,_NL,_NL,_NL,_NL,_NL,_NL,_NL
; Expanded for > 3k RAM.
display_file: defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
defs 32
defb _NL
; Start of the variables area used by BASIC.
variables: defb 0x80
; Start of the edit line used by BASIC.
edit_line:
p_end: end
Code: Select all
pasmo -v helloworld.asm helloworld.pCode: Select all
RAND USR 16526 http://edu.i-lo.tarnow.pl/inf/retro/005 ... o/0005.php
and screenshots of the original manual here:
http://www.zx81stuff.org.uk/zx81/info.p ... .Cover.jpg
I got it working with only minor modifications. Go into EDIT mode & enter thus. Labels are limited to 5 chars. And I call the PRINT subroutine in the ROM directly (CALL 0808).
Code: Select all
SPRNT POP HL
LD A,(HL)
INC HL
PUSH HL
CP FF
RET Z
CALL 0808
JR SPRNT
CALL SPRNT
DEFM "HELLO WORLD"
DEFB FF
I did all this to give me some confidence that what I was reading from one source, I could then transfer knowledge to the various ways of writing ZX81 assembly. Hope others who are struggling through it all (like me) can also learn & apply.
cheers
Daryn
