Assembly language runs fast. Assembly language produces small programs. But Assembly language takes nearly forever to write. That’s because you pretty much have to do everything from scratch.
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\nUnlike higher-level programming languages — even the C language — Assembly has no libraries. There are some routines you can access in the computer’s ROM or in the operating system, but beyond that you have to code everything. That includes input, output, math — you name it. It’s a lot of work.<\/p>\n
The payoff, of course, is that the code runs super fast, especially when compared with the typical BASIC program of the era.<\/p>\n
As an example, here is code I wrote in 1988 that displays a message on the screen:<\/p>\n
DOSSEG\r\n .MODEL small\r\n .STACK 100h\r\n .DATA\r\nmessage db \"This is an .EXE file.$\"\r\n\r\n .CODE\r\nstart: mov ax,DGROUP\r\n mov ds,ax\r\n mov ah,9\r\n mov dx,offset message\r\n int 21h\r\n\r\n mov ah,4Ch ;leave\r\n mov al,0 ;zero code\r\n int 21h\r\n\r\n END start<\/code><\/pre>\nThe resulting executable file is only 244 bytes long. That size cannot be equalled by any other programming language. Granted, it’s entirely unreadable. Even if I wrote all the necessary comments, few non-Assembly programmers would understand the code itself. But as you can see from my comments above, I probably felt comfortable enough with what I was doing not to write comments.<\/p>\n
Generally speaking, most programs do more than display a single line of text. And yet, in Assembly, every little bit of the program must be coded.<\/p>\n
Below is a snipped from code I wrote. It takes a string of text stored in memory and converts that text into a value. The value is stored in one of the processor’s registers:<\/p>\n
;---------------------------------------;\r\n; Calculate string si==> into bx ;\r\n;---------------------------------------;\r\nDECBIN proc near\r\n mov bx,0 ;zero out initial value\r\nDget_next:\r\n mov al,byte ptr [si] ;read value\r\n sub al,30h ;make binary\r\n cbw ;make into a word\r\n add bx,bx ;multiply bx by 10\r\n push bx ;save *2\r\n add bx,bx ;*4\r\n add bx,bx ;*8\r\n pop dx ;get back *2\r\n add bx,dx ;*8 + *2 = *10\r\n add bx,ax ;add new value\r\n inc si ;bump pointer\r\n cmp byte ptr [si],'0' ;end of string?\r\n jl Dleave ;go if so\r\n cmp byte ptr [si],'9' ;other possible end\r\n jle Dget_next ;if not, continue\r\nDleave:\r\n ret\r\nDECBIN endp<\/code><\/pre>\nThis code snippet is basically what you would call a function in any higher-level language. In Assembly, it’s a procedure<\/em>. In the C language, you would probably use the atoi()<\/em> function to accomplish the same thing. In Assembly, you have to write your own code, similar to what’s shown above.<\/p>\nThis snippet isn’t the only procedure you’d have to code. For each and every program you wrote in Assembly, you’ve have to write procedures for everything. Eventually you do develop your own procedure library, which you can use over and over. That includes tasks such as converting a string to a value, but also math fucntions, trigonometry, graphics — you name it. That takes time, and it’s a pain.<\/p>\n
And I loved<\/em> it!<\/p>\nAfter a while, however, I realized how awkward it was to write things in Assembly. I’ve kept all my Assembly code that I wrote on my PCs. The dates range from 1984 through about 1988. That was when I began to code in C, primarily because the development time was so much faster. But I still remember Assembly language. Those were the days.<\/p>\n","protected":false},"excerpt":{"rendered":"
Assembly language runs fast. Assembly language produces small programs. But Assembly language takes nearly forever to write. That’s because you pretty much have to do everything from scratch.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[14],"class_list":["post-3448","post","type-post","status-publish","format-standard","hentry","category-main","tag-programming"],"_links":{"self":[{"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3448","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3448"}],"version-history":[{"count":11,"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3448\/revisions"}],"predecessor-version":[{"id":3466,"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3448\/revisions\/3466"}],"wp:attachment":[{"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3448"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3448"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wambooli.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3448"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}