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 Sujet n° 21 |
PC-E500's secrets |
le 19/12/2002 @ 13:28
par Madis K.
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Let us all peek into the amazing worlds of pocket computers.
PC-E500 has a 16-bit timer(as far as I know). In my version it finds no use until PEEKing into memory addresses.
1)The first secret therefor is how to get fast-accurate timing from memory-mapped timer. The solution is PEEK!. Peeked values A, B and C are values from 0 to 255. What we get is a A+B*256+C*65536 formula, but the problem still lies as this number changes 928/15 which is about 62times per second we still need a better formula.
My best one till now is Timer=(a+b*256+c*65536)*15/928. |
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Warning: A non-numeric value encountered in /web5/aldweb/www/aldweb_com/www/thread.php on line 497
Réponse n° 11
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le 09/01/2004 @ 21:18
par Madis K.
visiteur
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Hey there,
I have made some research and try to find answers to my own questions:
1)The clock:You can calculate 15/928 and get a formula like this: (A+B*&100+C*&10000)*.016164 seconds or *16.164 to get ms. This rounding will add 206ns on each second, but the accuracy is even sufficient @16949seconds, where the error is 0.2169 seconds.
2)Sorry, my mistake. Both(CPU & quartz) are t° compensized.
3)Well, LINE is drawn like this:Every pixel's position is calculated. Then, because it can only draw in hex(GPRINT), it remembers the whole 8 pixels in that area and ORs it with pixel value. So LINE(0,0)-(239,31) calls GPRINT 240 times, so eventually, LINE command would draw 960 pixels and waste 0.2seconds taking 460800 clocks. I have a solution in ASM (276480px/sec => 230.4times faster, mail me)
4)In the 80's even ROM was called RAM, because it was accessible randomly.
5)It is SC-62015 and uses HD61202 & HD61203 for LCD drivers. I have the mnomonics and detailed instructions.
http://info.curtin.edu.au:8080/~iwoodsa/pce500/insttabl.html
I have *.pdf for both LCD drivers.
6)Yep, if nothing helps and PC keeps shutting down. I suggest testing if batteries are above 1.2V or if using accus, keep above 1.1V and 1st and 4th must have >500mA even if PC promises not to eat more than 11.67mA. Booting the machine chews about that much(500mA).
7)There are just enough commands:254!
The PRE byte and a MV ((n)),S operations are not supposed to be there. I guess that PRE &20 (bp±n),(bp±n) isn't just possible and there is no need to put the 3-byte value of S-stack to the address refered by the value in address n :( hmm
But these are not illegal, I haven't measured the clocks yet, but it seems that they are NOP's, so it has 3 NOP's: &00;&20;&BF
Whoo!!! That's it, bye 4 now ;)
Madis from Estonia
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Warning: A non-numeric value encountered in /web5/aldweb/www/aldweb_com/www/thread.php on line 497
Réponse n° 12
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le 10/01/2004 @ 21:57
par aldweb
visiteur
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Hi Madis,
Nice to read you back. Do you remember that you started this thread just a little more than one year ago 
I love it, it is a great summary of what needs to be known about the PC-E500 
1) Precision is good enough I guess
3) The LINE management is just the same in the PC-1360! This is not so suprising as the PC-1360 is a move from the PC-1350 to the PC-E500, some kind of wonderful hybrid 
4) ROM = Read Only Memory and RAM = Random Access Memory. There I am not so sure that in the 80's we would talk about RAM when meaning ROM... Distinction was much clearer than now with Flash ROM, NRAND and other new types of memory...
5) Great link to the famous Andrew Woods' PC-E500 pages
Happy New Year to You Madis, let's hope that 2004 will keep being very productive for you with the PC-E500... so that we will succeed to write a book from this forum thread in a few years! 
Greetz (from France),
aldweb
@+
aldweb
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