1 ÕÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ͸
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3 ³ To the VGA Trainer Program ³ ³
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5 ³ DENTHOR of ASPHYXIA ³ ³ ³
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6 ÔÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ; ³ ³
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7 ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
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8 ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
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14 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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17 Wow! The trainer has finally reached part 10! This will also be the
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18 first part introduced simultaneously to local BBS's and the INTERNET at
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19 the same time! Yes folks, I put up a copy of previous tutorials onto
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20 various ftp sites, and awaited the flames saying that the net.gurus
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21 already knew this stuff, and why was I wasting disk space! The flames
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22 did not appear (well, except for one), and I got some messages saying
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23 keep it up, so from now on I will upload all future trainers to ftp
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24 sites too (wasp.eng.ufl.edu , cs.uwp.edu etc.). I will also leave a
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25 notice in the USENET groups comp.lang.pascal and comp.sys.ibm.pc.demos
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26 when a new part is finished (Until enough people say stop ;-))
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28 I can also be reached at my new E-Mail address,
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29 smith9@batis.bis.und.ac.za
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31 Well, this tutorial is on Chain-4. When asked to do a trainer on
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32 Chain-4, I felt that I would be walking on much travelled ground (I have
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33 seen numerous trainers on the subject), but the people who asked me said
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34 that they hadn't seen any, so could I do one anyway? Who am I to say no?
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36 The sample program attached isn't that great, but I am sure that all you
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37 people out there can immediately see the potential that Chain-4 holds.
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40 If you would like to contact me, or the team, there are many ways you
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41 can do it : 1) Write a message to Grant Smith/Denthor/Asphyxia in private mail
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42 on the ASPHYXIA BBS.
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43 2) Write to Denthor, EzE or Goth on Connectix.
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44 3) Write to : Grant Smith
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49 4) Call me (Grant Smith) at (031) 73 2129 (leave a message if you
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50 call during varsity). Call +27-31-73-2129 if you call
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51 from outside South Africa. (It's YOUR phone bill ;-))
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52 5) Write to smith9@batis.bis.und.ac.za in E-Mail.
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54 NB : If you are a representative of a company or BBS, and want ASPHYXIA
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55 to do you a demo, leave mail to me; we can discuss it.
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56 NNB : If you have done/attempted a demo, SEND IT TO ME! We are feeling
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57 quite lonely and want to meet/help out/exchange code with other demo
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58 groups. What do you have to lose? Leave a message here and we can work
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59 out how to transfer it. We really want to hear from you!
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63 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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66 You people out there all have at least 256k vga cards. Most of you have
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67 512k vga cards, and some have 1MB vga cards. But what you see on your
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68 screen, as discussed in previous trainers, is 64k of data! What happened
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69 to the other 192k??? Chain-4 is a method of using all 256k at one time.
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71 The way this is done is simple. 1 screen = 64k. 64k * 4 = 256k.
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72 Therefore, chain-4 allows you to write to four screens, while displaying
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73 one of them. You can then move around these four screens to see the data
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74 on them. Think of the Chain-4 screen as a big canvas. The viewport,
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75 the bit you see out of, is a smaller rectangle which can be anywhere
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76 over the bigger canvas.
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78 +----------------------------+ Chain-4 screen
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83 +----------------------------+
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86 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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87 þ The size of the chain-4 screen
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89 The Chain-4 screen, can be any size that adds up to 4 screens.
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91 For example, it can be 4 screens across and one screen down, or one
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92 screen across and 4 screens down, or two screens across and two screens
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93 down, and any size in between.
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95 In the sample program, the size is a constant. The size * 8 is how many
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96 pixels across there are on the chain-4 screen, ie
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97 Size = 40 = 320 pixels across = 1 screen across, 4 screens down
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98 Size = 80 = 640 pixels across = 2 screens across, 2 screens down
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101 We need to know the size of the screen for almost all dealings with the
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102 Chain-4 screen, for obvious reasons.
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105 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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106 þ Layout of the chain-4 screen, and accessing it
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108 If you will remember all the way back to Part 1 of this series, I
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109 explained that the memory layout of the MCGA screen is linear. Ie, the
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110 top left hand pixel was pixel zero, the one to the right of it was
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111 number one, the next one was number two etc. With Chain-4, things are
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114 Chain-4 gets the 4 screens and chains them together (hence the name :)).
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115 Each screen has a different plane value, and must be accessed
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116 differently. The reason for this is that a segment of memory is only 64k
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117 big, so that we could not fit the entire Chain-4 screen into one
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120 All Chain-4 screens are accessed from $a000, just like in MCGA mode.
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121 What we do is, before we write to the screen, find out what plane we are
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122 writing to, set that plane, then plot the pixel. Here is how we find out
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123 how far in to plot the pixel and what plane it is on :
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125 Instead of the linear model of MCGA mode, ie :
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126 ÚÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄ¿
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127 ³00³01³02³03³04³05³06³07³08³09³10³11³ ...
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129 Each plane of the Chain-4 screen accesses the memory in this way :
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132 ÚÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄ¿
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133 ³00³ ³ ³ ³01³ ³ ³ ³02³ ³ ³ ³ ...
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136 ÚÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄ¿
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137 ³ ³00³ ³ ³ ³01³ ³ ³ ³02³ ³ ³ ...
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140 ÚÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄ¿
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141 ³ ³ ³00³ ³ ³ ³01³ ³ ³ ³02³ ³ ...
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144 ÚÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄÂÄÄ¿
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145 ³ ³ ³ ³00³ ³ ³ ³01³ ³ ³ ³02³ ...
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147 In this way, by choosing the right plane to write to, we can access all
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148 of the 256k of memory available to us. The plane that we write to can
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149 easily be found by the simple calculation of x mod 4, and the x
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150 coordinate is also found by x div 4. We work out our y by multiplying
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151 it by the size of our chain-4 screen.
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153 NOTE : It is possible to write to all four planes at once by setting the
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154 correct port values.
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156 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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159 The uses of Chain-4 are many. One could write data to one screen, then
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160 flip to it (the move_to command is almost instantaneous). This means
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161 that 64k of memory does not need to be set aside for a virtual screen,
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162 you are using the vga cards memory instead!
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164 Scrolling is much easier to code for in Chain-4 mode.
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166 It is possible to "tweak" the mode into other resolutions. In our demo,
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167 our vectors were in 320x240 mode, and our dot vectors were in 320x400
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170 The main disadvantage of chain-4 as I see it is the plane swapping,
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171 which can be slow. With a bit of clever coding however, these can be
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172 kept down to a minimum.
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174 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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175 þ The sample programs
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177 The first sample program is GFX.PAS. This is a until in which I have
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178 placed most of our routines from previous tuts. All the procedures and
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179 variables you can see under the INTERFACE section can be used in any
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180 program with GFX in the USES clause. In other words, I could do this :
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190 This program would compile perfectly. What I suggest you do is this :
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191 Rename the file to a name that suites you (eg your group name), change
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192 the first line of the unit to that name, then add all useful procedures
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193 etc. to the unit. Make it grow :-).
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195 The second file is the sample program (note the USES GFX,crt; up near
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196 the top!). The program is easy to understand and is documented. The bit
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197 that I want to draw your attention to is the constant, BIT. Because I
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198 am distributing this file to many places in text form, not binary form,
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199 I could not just add a .CEL file with the program. So what I did was
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200 write some text in one color then saved it as a .CEL . I then wrote a
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201 ten line program that did the following : Moving from left to right, it
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202 counted how many pixels were of color zero, then saved the byte value to
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203 an array. When it came across color one, is counted for how long that
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204 went on then saved the byte value and saved it to an array and so on.
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205 When it was finished, I converted the array into a text file in the
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206 CONST format. Not too cunning, but I thought I had better explain it ;-)
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208 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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211 There are other documents and sample programs available on Chain-4 and
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212 it's like : Try XLIB for one...
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214 Finally! Some BBS's have joined my BBS list! (Okay, only two new ones,
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215 but it's a start ;-)) All you international BBS's! If you will regularly
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216 download the tuts from an FTP site, give me your names!
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218 I own a car. The car's name is Bob. A few days ago, Bob was in an
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219 accident, and now has major damage to his front. Knowing insurance, I
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220 probably won't get much, probably nothing (the other guy wasn't insured,
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221 and I am only 18 :( ). I will probably have to find work in order to pay
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222 for my repairs. The point to this meandering is this : I am upset, so if
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223 you think you are getting a quote, you can just forget it.
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225 Oh, well. Life goes on!
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230 These fine BBS's carry the ASPHYXIA DEMO TRAINER SERIES : (alphabetical)
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232 ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍËÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍËÍÍÍÍÍËÍÍÍËÍÍÍÍËÍÍÍÍ»
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233 ºBBS Name ºTelephone No. ºOpen ºMsgºFileºPastº
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234 ÌÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÎÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÎÍÍÍÍÍÎÍÍÍÎÍÍÍÍÎÍÍÍ͹
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235 ºASPHYXIA BBS #1 º(031) 765-5312 ºALL º * º * º * º
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236 ºASPHYXIA BBS #2 º(031) 765-6293 ºALL º * º * º * º
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237 ºConnectix BBS º(031) 266-9992 ºALL º º * º * º
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238 ºPOP! º(012) 661-1257 ºALL º º * º * º
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239 ºPure Surf BBS º(031) 561-5943 ºA/H º º * º * º
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240 ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÊÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÊÍÍÍÍÍÊÍÍÍÊÍÍÍÍÊÍÍÍͼ
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242 For international users : If you live outside the Republic of South
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243 Africa, do the following : Dial +27, dont dial the first 0, but dial
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244 the rest of the number. Eg, for the ASPHYXIA BBS : +27-31-765-5312
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246 Open = Open at all times or only A/H
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247 Msg = Available in message base
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248 File = Available in file base
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249 Past = Previous Parts available
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252 ÚÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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257 Well folks, here it is - the long awaited for Chain-4 trainer. The
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258 routines are commented so I'm not going to say too much more here,
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259 except a few things.
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261 1: If ya don't understand this (not suprising its bloody cryptic!)
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262 then if ur serious go out and buy - Programming the EGA & VGA Cards
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263 I don't know who the book is by, so don't ask. Perhaps you know Greg?
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265 2: The code is unoptimised. I wrote it specifically for this conf. and
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266 I'm buggered if I'm gonna give out my wholely (sp? ahh stuff it :-))
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267 optimised code. If you want it faster, OPTIMISE IT!!
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268 HINT: Its faster to load ax, with a low byte/high byte combination
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269 and out a word instead of a byte at a time. If u don't know
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270 what I'm talking about, too bad :-)
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272 3: If you use/like/whatever this code, please give Asphyxia a mention.
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273 It wos bloody hard work figuring out how all this cr*p works, we
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274 couldn't have done it with out a little guidence (thanx Gregie Poo).
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276 4: LiveWire got interested in the whole tut/trainer idea and MAY be
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277 putting together a doc on how the whole thing works, including
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278 Pel-Panning which I haven't included here.
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281 5: Good luck with the code, and if you write anything with it, I'd
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282 appreciate having a look at it :-). Feel free to direct any comments
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283 about the code to me in this conf. Or at one of the contact addresses
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292 --------------------------------=[ Cut Here ]=-------------------------
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295 Program Chain4_Tut;
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304 Var Loop : Integer;
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308 Procedure Init_C4; Assembler;
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311 int 10h { set up bios initially for 13h }
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313 mov dx, 03c4h { Sequencer Address Register }
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314 mov al, 4 { Index 4 - Memory mode }
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315 out dx, al { select it. }
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316 inc dx { 03c5h - here we set the mem mode. }
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317 in al, dx { get whats already inside the reg }
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318 and al, 11110111b { un-set 4th bit - chain4 }
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322 mov al, 13h { Offset Register - allocates amt. mem for }
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323 out dx, al { 1 displayable line as - length div 8, so }
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324 inc dx { we use 80 (80*8) = 640 = 2 pages across }
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325 mov al, [Size] { and cause of chain-4 i.e. 256k display }
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326 out dx, al { mem, 2 pages down for four pages }
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328 { NOTE: setting AL above to 40 selects 1 }
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329 { page across and four down (nice for }
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330 { 1942 type scrolling games) and setting }
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331 { AL to 160 selects 4 pages across and 1 }
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332 { down, nice for horizontal scrolling }
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338 Procedure Cls_C4; Assembler;
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340 mov dx, 03c4h { 03c4h }
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341 mov al, 2 { Map Mask Register }
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344 mov al, 00001111b { Select all planes to write to }
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345 out dx, al { Doing this to clear all planes at once }
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349 xor di, di { set es:di = Screen Mem }
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350 mov ax, 0000h { colour to put = black }
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351 mov cx, 32768 { 32768 (words) *2 = 65536 bytes - vga mem }
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353 rep stosw { clear it }
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358 Procedure PutPixel_C4(X, Y : Integer; Col : Byte); Assembler;
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360 mov ax, [Y] { Y val multiplied by... }
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362 mov bl, [Size] { Size.... }
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363 shl bx, 1 { *2 - just 'cause! (I can't remember why!)}
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370 add bx, ax { add X val div 4 (four planes) }
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372 and cx, 00000011b { clever way of finding x mod 4, i.e. }
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373 mov dx, 03c4h { which plane we're in. }
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374 mov al, 2 { then use 03c4h index 2 - write plane sel.}
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375 out dx, al { to set plane to write to. }
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376 mov al, 1 { plane to write to = 1 shl (X mod 4) }
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384 mov es: [bx], al { then write pixel. }
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388 Function GetPixel_C4(X, Y : Integer): Byte; Assembler;
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390 mov ax, [Y] { Y val multiplied by... }
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392 mov bl, [Size] { Size.... }
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393 shl bx, 1 { *2 - just 'cause! (I can't remember why!)}
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400 add bx, ax { add X val div 4 (four planes) }
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402 and cx, 00000011b { clever way of finding x mod 4, i.e. }
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403 mov dx, 03c4h { which plane we're in. }
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404 mov al, 4h { then use 03c4h index 4 - read plane sel. }
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405 out dx, al { to set plane to read from. }
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406 mov al, cl { Plane to read from = X mod 4 }
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412 mov al, es: [bx] { then return pixel read }
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417 Procedure MoveScr_C4(X,Y : Integer); Assembler;
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419 mov ax, [Y] { Y val multiplied by... }
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421 mov bl, [Size] { Size.... }
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422 shl bx, 1 { *2 - just 'cause! (I can't remember why!)}
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426 add bx, [X] { Add X val }
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429 mov al, 0ch { CRTC address reg. }
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430 out dx, al { Start Address High Reg. }
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432 mov al, bh { send high byte of start address. }
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436 mov al, 0dh { Start Address Low Reg. }
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439 mov al, bl { send low byte of start address. }
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445 Procedure SetText; Assembler;
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454 While KeyPressed do ReadKey;
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463 WriteLn('Chain-4 Trainer...');
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464 WriteLn('By EzE of Asphyxia.');
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466 WriteLn('Contact Us on ...');
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469 WriteLn('the Asphyxia BBS (031) - 7655312');
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471 WriteLn('Email : eze@');
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472 WriteLn(' asphyxia@');
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473 WriteLn(' edwards@');
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474 WriteLn(' bailey@');
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475 WriteLn(' mcphail@');
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476 WriteLn(' beastie.cs.und.ac.za');
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478 WriteLn('or peter.edwards@datavert.co.za');
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480 WriteLn('Write me snail-mail at...');
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481 WriteLn('P.O. Box 2313');
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482 WriteLn('Hillcrest');
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501 Putpixel_C4(Random(320),Random(200),Random(256)+1);
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503 For Loop := 0 to 80 do
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505 MoveScr_C4(0,Loop);
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509 Loop := GetPixel_C4(100,100);
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511 WriteLn('Colour at location X:100, Y:100 was: ',Loop);
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514 --------------------------------=[ Cut Here ]=-------------------------
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projects / 16.git / blob