Absolute assembler for i8080/i8085を使ってSC-3000で、TMS9918を表示するプログラムを開発して行きます。
下記ホームページにある"Hello World" program for Z80 and TMS9918をi8080に移植しました。
https://www.msx.org/forum/development/msx-development/nyyrikkis-helloworld-code
; This is a "Hello World" program for i8080 and TMS9918 / TMS9928 / TMS9929 / ; V9938 or V9958 VDP. ; ; This version of Hello World was written by Timo "NYYRIKKI" Soilamaa ; 17.10.2001 ; Modified by TANAM ; 30.05.2018 ;---------------------------------------------------------------------- ; Configure this part: DATAP EQU 0BEH ; SC-3000 VDP Data port CMDP EQU 0BFH ; SC-3000 VDP Command port ;----------------------------------------------------------------------- ; Program starts here: ; ORG 0 ; Z80 starts always from here when power is turned on JP START START: DI ; We don't know, how interrupts works in this system, so we disable them. LXI SP,1FFFH LXI HL,00C0H LHLD 0001H ; Let's set VDP write address to #0000 XRA A OUT CMDP MVI A,40H OUT CMDP ; Now let's clear first 16Kb of VDP memory LXI HL,3FFFH CLEAR: MVI A,0 OUT DATAP DCX H MOV A,H ORA L NOP ; Let's wait 8 clock cycles just in case VDP is not quick enough. NOP JNZ CLEAR ; Now it is time to set up VDP registers: ;---------------------------------------- ; Register 0 to #0 ; ; Set mode selection bit M3 (maybe also M4 & M5) to zero and ; disable external video & horizontal interrupt OUT CMDP MVI A,80H OUT CMDP ;---------------------------------------- ; Register 1 to #50 ; ; Select 40 column mode, enable screen and disable vertical interrupt MVI A,50H OUT CMDP MVI A,81H OUT CMDP ;---------------------------------------- ; Register 2 to #0 ; ; Set pattern name table to #0000 XRA A OUT CMDP MVI A,82H OUT CMDP ;---------------------------------------- ; Register 3 is ignored as 40 column mode does not need color table ; ;---------------------------------------- ; Register 4 to #1 ; Set pattern generator table to #800 MVI A,1H OUT CMDP MVI A,84H OUT CMDP ;---------------------------------------- ; Registers 5 (Sprite attribute) & 6 (Sprite pattern) are ignored ; as 40 column mode does not have sprites ;---------------------------------------- ; Register 7 to #F0 ; Set colors to white on black MVI A,0F0H OUT CMDP MVI A,87H OUT CMDP ;---------------------------------------- ; Let's set VDP write address to #808 so, that we can write ; character set to memory ; (No need to write SPACE it is clear char already) MVI A,8 OUT CMDP MVI A,48H OUT CMDP ; Let's copy character set LXI H, CHARS MVI B, CHARS_END-CHARS COPYCHARS: MOV A,M OUT DATAP INX H NOP ; Let's wait 8 clock cycles just in case VDP is not quick enough. NOP DCR B JNZ COPYCHARS ; Let's set write address to start of name table XRA A OUT CMDP MVI A,40H OUT CMDP ; Let's put characters to screen LXI H,ORDER MVI B,ORDER_END-ORDER COPYORDER: MOV A,M OUT DATAP INX H DCR B JNZ COPYORDER ; The end HLT ; Character set: ; -------------- ORDER: DB 1,2,3,3,4,0,5,4,6,3,7,0 ORDER_END: CHARS: ; H DB 88H,88H,88H,0F8H,88H,88H,88H,00H ; e DB 00H,00H,70H,88H,0F8H,80H,70H,00H ; l DB 60H,20H,20H,20H,20H,20H,70H,00H ; o DB 00H,00H,70H,88H,88H,88H,70H,00H ; W DB 88H,88H,88H,0A8H,0A8H,0D8H,88H,00H ; r DB 00H,00H,0B0H,0C8H,80H,80H,80H,00H ; d DB 08H,08H,68H,98H,88H,98H,68H,00H chars_end: DB 00H END
次は、SG-1000 Loaderを書き直していきます。
