Page 5 of 8
Posted: Tue Dec 06, 2011 1:33 pm
by ElEctric_EyE
Ed, you're right. The monitor can't just simply spit out characters, although it does at times, if it's going to scroll up and down.
So I've searched HESMON with regard to video matrix pointer ($D018, bits 4-7), the default video matrix area is @$0400. HESMON stores a #$17, which bit 4 does not change the default for using $0400.
My zero page blockRAM covers the bottom 4K. So this is good for compatibility as the C-64 40x25 video matrix will be from $0000_0400-$0000_07E7. That will be 40 characters across at 16bits each and 25 characters down at 16bits each, i.e. 640x400. That will leave 40x5 (640x80) at the bottom of the screen that will be available for some "stuff".
As for HESMON, it originally resided @$0000_C000-$0000_CFFF. I will have to move it to $FFFF_C000-$FFFF_CFFF. Next step is to find all references to $Cxxx (for variables and such) within the program, as I will have to manually change them to $FFFF_Cxxx. As65 (I'll refer to Bitwises' 65Org16 assember as As65 from here on out) will want to convert those addresses to $0000_Cxxx.
Posted: Tue Dec 06, 2011 7:57 pm
by ElEctric_EyE
I found only 1 instance in the original HESMON code where it stores a value within it's own boundary and it's strange. It stores a #$20 and changes an opcode from a JMP to a JSR, and there is no other instance to change it back to a JMP...
When I get closer to tearing apart this code I'll be keeping my eye open for an indirect indexed pointing to $0400.
Now I am off to commenting all JMP's and JSR's to external routines. Most are Kernal, just a few branches to Basic.
EDIT: Looking at the last page of the 1982 Owner's Manual I find some useful info:
Code: Select all
HESMON uses 33 bytes near the bottom of the machine stack ($120-$141) for its variable storage.
Posted: Wed Dec 07, 2011 5:27 am
by teamtempest
I found only 1 instance in the original HESMON code where it stores a value within it's own boundary and it's strange. It stores a #$20 and changes an opcode from a JMP to a JSR, and there is no other instance to change it back to a JMP...
When I get closer to tearing apart this code I'll be keeping my eye open for an indirect indexed pointing to $0400.
Now I am off to commenting all JMP's and JSR's to external routines. Most are Kernal, just a few branches to Basic.
Ah, I remember HESMON. One of my first software purchases for my C64. It came on a ROM cartridge. That would account for its lack of treating itself and nearby memory as RAM.
If in cartridge ROM form HESMON does map itself into where the 4K RAM block normally appears at $C000-$CFFF then essentially there would be no RAM at all visible from $A000-$FFFF. It's all ROMs and I/O.
Dunno exactly why a ROM cartridge would want to replace a JMP with a JSR, but maybe that was a later addition after the ROM was downloaded. Or some kind of self-test, perhaps.
You might check to see whether the code plays around with memory location $1, the memory mapping "register".
Posted: Wed Dec 07, 2011 7:47 am
by BigEd
I found only 1 instance in the original HESMON code where it stores a value within it's own boundary and it's strange. It stores a #$20 and changes an opcode from a JMP to a JSR, and there is no other instance to change it back to a JMP...
This starts to sound like copy protection to me: it won't work very well in RAM but will be fine in the original ROM.
Posted: Wed Dec 07, 2011 8:04 pm
by ElEctric_EyE
I must've had too many windows open when I said HESMON was replacing a $4C (JMP) with a $20 (JSR). After looking at it again, it is storing a $20 where a $20 already is... Still a curiousity but I don't have time for it right now.
...It's all ROMs and I/O...You might check to see whether the code plays around with memory location $1, the memory mapping "register".
It does store a #$37 at location $01, enabling Basic, Kernal ROMs and I/O. Also this is an image that I stored years ago on a C64 5 1/4" floppy right alongside of Micromon. I'm not sure how I got it, although I think I typed it in from Compute! or Compute's Gazette and the image does work in VICE.
...I have only to make a separate table for the text strings and opcodes, and As65 will be able to assemble it and create the .bin for the bin2coe to create the ROM. Then I'll try substituting 2 routines with 2 of mine, namely character in and character out, and maybe will see some sort of life.
__________________________________________________________________________________________________________________________
In the meantime today I spent a greater portion trying to figure out a problem I am having with my ATTBUTE routine. It involves using a LDA COLTABLE,X. COLTABLE=$FFFFC980. The original code does not work. It's plotting all zero values. I've tried replacing the label with the actual address, also tried changing the address to $FFFFE000 (middle of nowhere within 16K blockRAM) with no luck...
Code: Select all
ATTBUTE LDA CHRATTR ;get color from bits 0,1,2,3
AND #$000F
ASL A
ASL A ;multiple by 4 for easy indexing
TAX
LDA COLTABLE,X
STA PXLCOL1
INX
LDA COLTABLE,X
STA PXLCOL2
INX
LDA COLTABLE,X
STA PXLCOL3
Today, I found out what does work: If I replace LDA COLTABLE,X with LDA COLTABLE, LDA COLTABLE+1, LDA COLTABLE+2 it does lookup and plot the correct color, so no problem with blockRAM (there was one with 8Kx16). I'm thinking there's a problem with the 65Org16 core using Absolute Indexed with X. I will double check this against Arlet's original...
BTW, when it comes time to make room for HESMON and original zero page variables, I will be moving my routines from $FFFFC000 to $FFFFD000 and moving all my zero page variables to $00000100. Posting this now makes me realize I need to re-allocate all original stack variables from $0100-$01FF to $00010000-$0001FFFF...
Posted: Wed Dec 07, 2011 9:30 pm
by ElEctric_EyE
...In the meantime today I spent a greater portion trying to figure out a problem I am having with my ATTBUTE routine. It involves using a LDA COLTABLE,X. COLTABLE=$FFFFC980. The original code does not work. It's plotting all zero values. I've tried replacing the label with the actual address, also tried changing the address to $FFFFE000 (middle of nowhere within 16K blockRAM) with no luck...
I've looked at the .bin and it seems the problem lies within As65 if I'm not mistaken.
I am observing an opcode $B5 (LDA ZP,x) when it should be an opcode $BD (LDA a,x). Bitwise, please help!
Posted: Wed Dec 07, 2011 11:59 pm
by BitWise
Is address argument to the LDX ...,X an external symbol or a constant value?
You can insert a '|' or '!' before the address to force the assembler to generate an ABS,X mode rather a ZP,X
For example LDA |$80,X should generate BD 80 00 instead of B5 80. The same should work for the 65Org16 mode.
Posted: Thu Dec 08, 2011 12:29 am
by ElEctric_EyE
Thanks for a quick response
Is address argument to the LDX ...,X an external symbol or a constant value?...
Not an LDX...,X. It is an LDA ...,X.
Last test I used a constant of $FFFFE000,X no labels... Instead of translating the LDA $FFFFE000,X to a 00BD, FFFF, E000; it is translating it to 00B5,E000 according to my hex editor.
Posted: Thu Dec 08, 2011 10:51 am
by ElEctric_EyE
Ok, that worked. Thanks!
Posted: Tue Dec 13, 2011 12:52 am
by ElEctric_EyE
I've done some more digging into the original 8bit C-64 Hashmon code...
Using VICE C-64 emulator on PC and running the Hashmon code is proving invaluable. I instantly found the main loop using the VICE monitor. It starts @ $C24D and is a very short loop with just a few other JSRs JMP's that branch out. I still need to follow these to their ends, but right now I am aiming for a startup screen that jives with the original Hashmon. This will at least prove my output character routine is sufficient. Also, I've found within the main loop, Hashmon reads characters typed in from the keyboard stored at $39.
There are 2 Indirect JMP's within the 4K worth of code which concern me:
a JMP ($00C1), and a JMP ($0120). I will figure them out eventually.
I found the Indirect Indexed screen matrix pointer @$D1, $D2. Directly related is the $F3, $F4 Indirect Indexed pointer to screen color RAM. These are some of the "constant" variables which are very important. Not so much the screen color RAM though.
I am finding there is alot I would like to delete from the original code. Maybe trim it to 1/2 the size it is. No need for tape storage etc... Alot of variables saved for basic and kernal, which are not needed here.
Posted: Tue Dec 13, 2011 6:47 pm
by ElEctric_EyE
...You can insert a '|' or '!' before the address to force the assembler to generate an ABS,X mode rather a ZP,X
For example LDA |$80,X should generate BD 80 00 instead of B5 80. The same should work for the 65Org16 mode.
Your new
update works, so no more need for '|' or '!'. Thanks!
Posted: Fri Dec 16, 2011 1:26 am
by ElEctric_EyE
I've come across
6 instances like the one below. These are the last inconsistencies I have left before fully translating HESMON from 8bit 6502 to 16bit 65Org16. This example below is a pic taken from VICE running the original HESMON image and disassembling itself. This is just abit of some tricky coding here. Check out the BEQ's. Almost like the BIT $3AE6 ($2C, $E6, $3A)is non function
Code: Select all
eC127:
JSR eC13C
BEQ eC137
CMP #$29
BEQ eC139
ORA #$08
CMP #$2C
BNE eC11B
BIT $3AE6
eC139:
LDX $3C
RTS
When the CPU sees a BEQ $C137, it looks like this:
Posted: Fri Dec 16, 2011 6:12 am
by teamtempest
I've come across 6 instances like the one below
An old space-saving trick discussed in more detail in this thread:
viewtopic.php?t=1614
Posted: Fri Dec 16, 2011 9:35 pm
by ElEctric_EyE
Excellent. Thanks for pointing that out, I didn't think to check this site, duh! Using .BYTE $2C made it so I could use the labels that As65 was looking for.
Done creating a workable .bin image...
Posted: Tue Dec 20, 2011 1:31 am
by ElEctric_EyE
Thinking back to the equivalent $FFD2 CHROUT routine on the C-64, I think I've got my routine down pretty close. And thanks to TeamTempest for contributing.
Sorry for the length, but I have now incorporated the PLTPOS and ATTBUTE routines
within the PLTCHR routine. Plot Enable is now a bit value...
Also, all 16bits of the databus are used to define a character for the 8bit video TFT. The bit placements are commented within the assembly. Simply put, the lower 7 bits define the ASCII character, and bits 8thru15 are character plot enable, size, color and font attributes (1,3,4, & 1 bits respectively)...
The PLTCHR routine still needs just abit of final fine tuning to detect when to increment the Y Plot value, after reaching max X with variable character sizes, in order to continue plotting to the second and consecutive lines. Working...
I thought I would post the code now, even though it is incomplete, in order to show how many ASLs and LSR's are needed.
Code: Select all
PLTCHR STA CHR ; Plot Character Subroutine variable (1-7) H and V size
TYA ; save all reg's
PHA
TXA
PHA
ATTBUTE AND #%00000111100000000
LSR A ;get color VALUE from bits 8,9,10,11
LSR A
LSR A
LSR A
LSR A
LSR A ;multiply by 4 for easy indexing
TAX
LDA COLTABLE,X
STA PXLCOL1
INX
LDA COLTABLE,X
STA PXLCOL2
INX
LDA COLTABLE,X
STA PXLCOL3
LDA CHR ;check bits 12,13,14 for size
AND #%0111000000000000
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A ;make size 1x through 7x, no size 0!
STA XWIDTH
STA YWIDTH
LDA CHR ;check font bit 15, 1=C64 , 0=3x5
AND #%1000000000000000
CMP #$8000
BEQ n64
LDA #$08
STA PATROW
STA CHRXLEN
STA CHRYLEN
LDA #$CA00
STA CHRBASE
LDA #$0080
STA SENTINEL
JMP porc
n64 LDA #$04
STA CHRXLEN
LDA #$05
STA PATROW
STA CHRYLEN
LDA #$CD00
STA CHRBASE
LDA #$0800
STA SENTINEL
porc LDA CHR ;test PE bit 7 for plot or clear
AND #%0000000010000000
CMP #$80
BNE plot2
LDA SCRCOL1
STA TMPCOL1
LDA SCRCOL2
STA TMPCOL2
LDA SCRCOL3
STA TMPCOL3
JMP PLTPOS
plot2 LDA PXLCOL1
STA TMPCOL1
LDA PXLCOL2
STA TMPCOL2
LDA PXLCOL3
STA TMPCOL3
PLTPOS LDA #$2A ;set x address
STA DCOM
LDA XPOS
PHA
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
STA DDAT ;X START MSB
PLA
AND #$00FF
STA DDAT ;X START LSB
LDA XPOS
CLC
LDX XWIDTH
AC ADC CHRXLEN
DEX
BNE AC
STA XPOS ;UPDATE X POSITION
INC XPOS ;NEXT CHR WILL GO HERE
SEC
SBC #$01
PHA
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
STA DDAT ;X END MSB
PLA
AND #$00FF
STA DDAT ;X END LSB
LDA #$2B ;set y address
STA DCOM
LDA YPOS
PHA
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
STA DDAT ;Y START MSB
PLA
AND #$00FF
STA DDAT ;Y START LSB
LDA YPOS
CLC
LDX YWIDTH
AD ADC CHRYLEN
DEX
BNE AD
SEC
SBC #$01
PHA
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
LSR A
STA DDAT ;Y END MSB
PLA
AND #$00FF
STA DDAT ;Y END LSB
CACALC LDA #$2C ; Prepare TFT to Plot
STA DCOM
LDA CHR
AND #$7F ; an ascii char ? - ATTRIBUTE INFO
CMP #$0D
BNE nnull
LDX #$00
STX XCHRPOS
INC YCHRPOS
LDA #$00 ; make undefined char's a defined zero (space character)
nnull SEC
SBC #$20
ASL A ; * 2
ASL A ; * 4
ASL A ; * 8
CLC
ADC CHRBASE ; add pointer to base either CA00 (C64) or CD00(3x5) (carry clear)
TAY
loop7 LDA XWIDTH ; plot row repeat count (1-7)
STA PIXROW
loop4 LDA CHARPIX,Y ; $FFFFCA00(c64) or $FFFFCD00(3x5)
ASL A ;
ASL A ;
ASL A ;
ASL A ;
ASL A ;
ASL A ;
ASL A ;
ASL A ; shift out upper 8 bits, don't care for 8-bit byte character font
ORA SENTINEL ; $0080 (C64) or $0800 (3x5)
ASL A ; get a pixel
loop5 PHA ; save remaining pixel row data
LDX YWIDTH ; plot column repeat count (1-7) (same as PLTHGT?)
BCC xwnp ; b: clear ('blank')
xwp LDA TMPCOL1
STA DDAT ; plot RED pixel TFT data
LDA TMPCOL2
STA DDAT ; plot GREEN pixel TFT data
LDA TMPCOL3
STA DDAT ; plot BLUE pixel TFT data
DEX
BNE xwp
BEQ nxtpix ; b: forced
xwnp LDA SCRCOL1
STA DDAT ; plot RED "blank" pixel TFT data
LDA SCRCOL2
STA DDAT ; plot GREEN "blank" pixel TFT data
LDA SCRCOL3
STA DDAT ; plot BLUE "blank" pixel TFT data
DEX
BNE xwnp
nxtpix PLA ; get pixel row data back
ASL A ; another pixel to plot ?
BNE loop5 ; b: yes (sentinel still hasn't shifted out)
DEC PIXROW ; repeat this row ?
BNE loop4 ; b: yes
INY
DEC PATROW ; another pattern row to plot ?
BNE loop7 ; b: yes
PLA
TAX
PLA
TAY ;reload reg's
RTS