Search found 6 matches

by BigAkuma
Wed Feb 05, 2020 8:33 am
Forum: General Assembly Programming
Topic: Why value not stored into A register?
Replies: 3
Views: 876

Re: Why value not stored into A register?

Hi. Ok I finally understand what was the problem. I thought that when we do "ld a, (&9000)", we assign the address &9000 to A, and any time we change the value of A, it is changed to the address &9000, as if A was a pointer. So, this is already solved. But now, I have one question: is it possible to...
by BigAkuma
Tue Feb 04, 2020 10:43 am
Forum: General Assembly Programming
Topic: Why value not stored into A register?
Replies: 3
Views: 876

Why value not stored into A register?

Hi. Sorry for this next topic, but it is a bit unrelated to the other previous message. Let's consider this piece of code, that appears in Lesson 3: org &8000 ld a, (&9000) ld bc, (&9001) cp 0 jr z, MathAdd cp 1 jr z, MathSub ld a, 0 SaveResult: ld a, (&9003) ret MathSub: ld a, c sub b jr SaveResult...
by BigAkuma
Tue Feb 04, 2020 6:04 am
Forum: Introductions
Topic: Hi from Japan
Replies: 3
Views: 892

Re: Hi from Japan

Welcome to the forum, I'm glad you're finding my tutorials useful! If you're looking to do some MSX assembly programming, can I strongly recommend you take a look at Grauw's website, as it's a wealth of MSX1/2 info http://map.grauw.nl/resources/ Ah, yes, I know that website. But for now, I prefer t...
by BigAkuma
Tue Feb 04, 2020 6:00 am
Forum: General Assembly Programming
Topic: Help about piece of code
Replies: 3
Views: 892

Re: Help about piece of code

Hey there! this is CPC code isn't it... in 8 bit systems when a register is 0 and we subtract 1 it 'rolls around' back to 255 I can't actually remember writing this example - I did it about 3 years ago, and maybe I'd do it differently today. The example is going to repeat while A>=0 ... 255 is effe...
by BigAkuma
Sun Feb 02, 2020 10:26 am
Forum: General Assembly Programming
Topic: Help about piece of code
Replies: 3
Views: 892

Help about piece of code

Hi. This piece of code: ScreenSize equ &4000 org &8200 ld a, %00001111 FillAgain: ld hl, &C000 ld de, &C000+1 ld bc, ScreenSize-1 ld (hl), a ldir dec a cp 255 jp nz, FillAgain ret Just two questions: 1) In this specific example, I don't understand well how "CP" works and why we need it. According to...
by BigAkuma
Sun Feb 02, 2020 10:08 am
Forum: Introductions
Topic: Hi from Japan
Replies: 3
Views: 892

Hi from Japan

Hi. Thanks for your great content. I just found your website on the net. I want to write software for the MSX 1 and your lessons are maybe the best around, for people who are new to assembly language. I know how to code in C/C++, BASIC, LUA and TCL/TK. Now trying to get things done they way they sho...

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