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ZX Review #3-4
22 июля 1997 |
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reader-reader - I. Roshchin. Display driver for the computer, "Pentagon-128.
The Reader - Reader
(C) Ivan Roshchin, Moscow, 1997.
Screen drivers for your computer
"The Pentagon-128.
Bring to your attention
screen driver - a small procedure in assembly (211 bytes)
caused an interrupt 2-nd
kind. Using this driver,
very easy to write a program
realizing the full screen MULTICOLOR - effect (each row
together with a border drawn his
color). In this case, all the problems
associated with different timing for different types of
computers, are solved by simply replacing driver (the proposed
option designed to "Pentagon-128).
Here is a sample program that uses the driver for the
implementation of simple effect - the screen
move three colored bands. Pay special attention to the fact
as programmed by this effect,
as well as the length of the program -
only 217 bytes (without driver).
140.
ORG # 6000
; MAIN PROGRAM:
N EQU 37; vertical dimension in the familiarity
LD HL, # 5800; INSTALLATION
LD DE, # 5801; ATTRIBUTES
LD BC, # 2FF; (NOT REQUIRED)
LD (HL), L
LDIR
; Draw the grid (necessary for MULTICOLOR'A):
LD HL, # 4000
LP1 XOR A
BIT 0, H
JR NZ, NE_FF
CPL
NE_FF LD (HL), A
INC HL
LD A, H
CP # 58
JR NZ, LP1
; INITIALIZING THE EFFECT:
CALL E_INIT
; TO CAUSE THE DRIVER TO THE INTERRUPTION,
; SHAPING table, for example, C ADDRESSES
; # FEFE:
LD HL, # FE00
LD B, 0
LOOPT LD (HL), # 62
INC HL
DJNZ LOOPT
LD (HL), # 62
LD A, # FE
LD I, A
IM 2
LOOP_M HALT
CALL EFFECT
IN A, (254), something pressed?
CPL
AND% 00011111
JR Z, LOOP_M; IF NO
IM 1
RET; Exit
;--------------------------------------; Obtain the effect of
"Color bars": ; Entry point for initialization:
E_INIT LD HL, DATA +40
LD DE, DATA +41
LD BC, 300
LD (HL), 0
LDIR
LD HL, DATA
LD DE, DATA +1
LD BC, 39
LD (HL), 7
LDIR
RET
; Entry point for CALL EVERY INTERRUPT:
EFFECT LD HL, (A_BEG)
LD B, 1
LD A, (A_WAY)
CALL MOVE
LD (A_WAY), A
LD (A_BEG), HL
LD HL, (B_BEG)
LD B, 2
LD A, (B_WAY)
CALL MOVE
CALL MOVE
LD (B_WAY), A
LD (B_BEG), HL
LD HL, (C_BEG)
LD B, 4
LD A, (C_WAY)
CALL MOVE
CALL MOVE
CALL MOVE
LD (C_WAY), A
LD (C_BEG), HL
RET
; PROCEDURE MOVE Moves the band:
MOVE AND A
JR NZ, MOVE_D
; Upward shift:
LD A, H
OR L
JR Z, MOVE_D
MOVE_UP DEC HL
PUSH HL
LD DE, DATA
ADD HL, DE
LD A, (HL)
OR B
LD (HL), A
LD DE, 40
ADD HL, DE
LD A, (HL)
XOR B
LD (HL), A
POP HL
XOR A
RET
; Shift down:
MOVE_D LD DE ,297-40
AND A
SBC HL, DE
PUSH AF
ADD HL, DE
POP AF
JR Z, MOVE_UP
PUSH HL
LD DE, DATA
ADD HL, DE
LD A, (HL)
XOR B
LD (HL), A
LD DE, 40
ADD HL, DE
LD A, (HL)
OR B
LD (HL), A
POP HL
INC HL
LD A, 1
RET
A_BEG DW 0; COORDINATES
B_BEG DW 0; BANDS
C_BEG DW 0
A_WAY DB 0; DIRECTION
B_WAY DB 0; TRAFFIC
C_WAY DB 0
;--------------------------------------
ORG # 6262
;=======================================
; Display driver:
DI
PUSH AF; Stores the value of
PUSH BC; USED
PUSH DE; REGISTERS
PUSH HL
PUSH IX
PUSH IY
LD (M122 +1), SP
; Delay while the beam did not get to the top line:
LD D, H; WAIT
LD E, L; WAIT
LD BC, 171; WAIT
LDIR; WAIT
LD IX, DATA +1; ADDRESS TABLE
LD HL, # 5720; CURRENT ADDRESS ATTRIBUTES
LD BC, 3; B is always 0, C-COUNTER.
LD A, (DATA); COLOR FIRST STRING
LD YL, A; REMEMBER COLOR
LD DE, # 20
; BEAM AT THE BEGINNING OF NEXT LINE:
M3 LD SP, HL
SBC HL, DE
LD A, YL
OUT (254), A
LD A, (IX +1)
LD YL, A
AND A
RLCA
RLCA
RLCA
OR (IX)
LD D, A
LD A, H
CP # 58
JR C, NO_ATR
CP # 5B
JR NC, NO_ATR2
And half the line already drawn,
, And attributes can be changed.
LD E, D
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
; 16 bytes COMPLETE BEAM IN THE BEGINNING
; Following lines:
LD A, D
AND 7
OUT (254), A
LD A, C
; I still ATTRIBUTES:
LD C, # 20; BC = # 20
ADD HL, BC
LD SP, HL
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
PUSH DE
LD C, A
INC XL
LD A, 0; WAIT
NEXT_L LD DE, # 10
INC IX
DEC C
JR NZ, M10
LD C, 4
ADD HL, DE
JR M3
M10 SBC HL, DE
JP M3
; Get here, if the current line
; Belong entirely to the curb:
NO_ATR LD A, 0; WAIT
LD A, 0; WAIT
; CHECK ON IMPORTANCE HL: Is it time to
; EXIT INTERRUPT?
NO_ATR2 LD DE, # 5720 + ((N-1) * # 20)
AND A
SBC HL, DE
JR NC, M122
ADD HL, DE
LD DE, (0); WAIT
LD DE, (0); WAIT
NOP; WAIT
LD A, (IX)
OUT (254), A
LD A, (IX); WAIT
LD A, (IX); WAIT
LD A, (IX); WAIT
LD A, (IX); WAIT
INC DE; WAIT
LD DE, # 20
ADD HL, DE
INC XL
JR NEXT_L
; OUT OF INTERRUPTION:
M122 LD SP, 0
POP IY; RESTORES
POP IX; register value
POP HL
POP DE
POP BC
XOR A
OUT (254), A
POP AF
EI
RET
;=======================================
ORG # 7001
;--------------------------------------; ARRAY OF DATA FOR
MULTICOLOR'A: DATA DS 320
;-------------------------------------- 2
Some remarks on the
Program:
- You can see nedokumenti
an orthonormal click INC XL. Such
its designation is perceived
assembler ZX ASM 3.0. But in
Other assemblers, as well as
STS debugger is denoted
as INC LX (code DD 2C).
- Lines of code that are marked
commentary "WAIT", need
only for the delay.
- Address of the beginning of the array DATA necessarily
necessarily must be odd.
When working with a driver programmer can assume that the
video memory - an array of data located at DATA and
occupies as many bytes as
MULTICOLOR'a lines he wants to see on the screen. The value of
each bytes in the array - a number between 0
to 7, indicating the color of the corresponding row in the
screen. If array does not change, MULTICOLOR-effect will be
fixed. That he was moving, it is necessary
every 1 / 50 seconds (or less)
modify data in the array.
Vertical size MULTICOLOR'a in familiarity is determined by
the variable N. This value can not be arbitrary, but only
within the boundaries of 1 .. 7 and 31 .. 37 inclusive. The
point that the condition of the end of the driver is only
checked if the current row is entirely true to the curb (or
at the top or the bottom of the
screen).
Even if you "Pentagon128", a driver can not work
very good (band blink, and so
etc.). The fact that even the computers of one type of situation
INT'a regarding staffing
clock may vary.
In this case, you can try
adjust the value of the delay in
driver. To do this, find the commands marked "WAIT", at the
beginning of the driver. You will see a snippet:
147.
LD D, H; WAIT
LD E, L; WAIT
LD BC, 171; WAIT
LDIR; WAIT
2
Achieve the best quality
Images can be loaded by changing the BC number, or adding NOP'y
(or a combination of both). Monitor the result of the changes
it is convenient, if Every time you start the program appears
on the screen a still picture with colored lines. To do this,
remove the line CALL E_INIT and CALL EFFECT, and
instead of a string DATA DS 320 to put the following lines:
DATA DB 7,0,4,0,4,0,4,0
DB 4,0,4,0,4,0,4,0
DB 4,0,4,0,4,0,4,0
DB 4,0,4,0,4,0,4,0
DB 4,0,4,0,4,0,4,0
DB 4,0,4,0,4,0,4,0
DB 4,0,4,0,4,0,4,0
DB 4,0,4,0,4,0,4,7
DB 0,1,2,3,4,5,6,7
DB 4,0,4,0,4,0,4,0
.......................
When using the driver
their programs better synchronize with the interrupt command
HALT. This is due to the fact that at the time of interruption
of the processor is busy executing a long command, the driver
later, will begin its work, and the picture can be displaced.
If you do decide to program MULTICOLOR-effects
without using a driver, you have to carefully calculate, for
how many cycles performed that
a portion of the program. So
as constantly looking in the directory of information about the
duration of the execution of one or the other team may be
uncomfortable, I recommend to use for this purpose program
"HELP_Z80" - an electronic directory of commands Microprocessor
Z80, which You can download any assembler debugger instead of
STS (or along with it) and call at the right moment by pressing
a couple buttons.
P.S. I propose to announce
the best graphic effect
effect created by
driver.
*
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