- Hard code it – 00010101B would be a control word, followed by a time constant, rising edge. The assembler wants the B suffix for binary. Efficient, but dumb.<\/li>
- Assign each bit it’s decimal or hex value, and then add them up together. To get the same word as above, we’d do (128*0)+(64*0)+(32*0)+(16*1)+(8*0)+(4*1)+(2*0)+(1*1)<\/li>
- Have 8 discrete 1 bit values, and left shift them onto the accumulator – Bit 7 would be shifted 7 times, bit 6 shifted 6 times, etc…<\/li><\/ul>\n\n\n\n
![\"\"](\"https:\/\/paulcarbone.com\/50days\/wp-content\/uploads\/2022\/02\/Z80-Ramblings-Page-1.drawio.png\")
<\/figure>\n\n\n\nLets first experiment with shifting a value. But even before we do that<\/em>, we have to see about prompting the user with what to enter. JFC, you gotta do everything <\/em>yourself in assembly. <\/p>\n\n\n\n
OK, I’ve been trying to write a simple god damn message to the terminal for the last 90 minutes.
<\/p>\n\n\n; HELLO WORLD\n; SETUP SOME THINGS\nBDOS EQU 5<\/span>\nWCONF EQU 2<\/span>\nRCONF EQU 1<\/span>\nRBOOT EQU 0<\/span>\nTPA EQU 100<\/span>H\nCR EQU 0<\/span>DH\nLF EQU 0<\/span>AH\nCTRLZ EQU 1<\/span>AH\n\n ORG TPA\n \nSTART1: LD E,LF ;OUTPUT LINE FEED\n LD C,WCONF \n CALL BDOS\n\nDERP: LD E,'$'<\/span> ;OUTPUT A $\n LD C,WCONF\n CALL BDOS \n\nMESG: DB \"HELLO WORLD!\"<\/span>\n LD HL,MESG\n \nPRNT: LD E,(HL) ;HL POINTS TO CHAR TO LOAD INTO A\n INC HL ;INCREMENT HL\n LD C,WCONF ;SET C W\/ WRITE BYTE\n CALL BDOS\n JP PRNT ;GO BACK TO THE TOP OF THE PRINT<\/span> ROUTINE\n <\/code><\/div>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\nI hate this.<\/p>\n\n\n\n
UPDATE: <\/p>\n\n\n\n
I’m dumb. I rewrote the program after some folks pointed out a few extra-stupid mistakes, and it at least now vomits onto the screen!<\/p>\n\n\n\n
Gotta have the DB block at the end, otherwise it’s just interpreted as code (duh)
Gotta PUSH & POP the HL register, cause it gets trashed by the BDOS Call.
What you see below is what happens when you don’t have a test at the end of the string. The loop is printing everything<\/em> (the contents of the entire memory map).
<\/p>\n\n\n\n