[TI83p-ASM] Come here to worship 83pa28d!

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What are your toughts about 83pa28d?

Ultimate tutorial for the 83p
2
20%
Only tutorial for the 83p
0
No votes
Very good except the errors
7
70%
I liked the style but the explanations sucked
1
10%
 
Total votes: 10

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Jim e
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Post by Jim e »

No, its 4 tstates. It's not jumping to the address pointed to by HL, its jumping to the address in hl. So only requires a read of 1 byte.
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King Harold
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Post by King Harold »

Jim is right, it's actually a bad mnemonic, but I guess we'll have to live with it.. blame ZiLOG..

On the other hand, it's a jump, which is in fact a load, but it looks like a jump. So one could think 'jump to the instruction pointed at by hl' which would explain the reference brackets.
If jp xxx was defined as 'ld pc,xxx' then it would be completely wrong.


btw, you can't very well load a 16bit reg with a 8bit value.. 'ld pc,(hl)' would be completely impossible.
Andy_J
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Post by Andy_J »

Oh, right, I knew that, I was just mis-thinking it =\


jp hl would probably be best... but then again you could have a label called hl... Gah. It's just a crappy mnemonic :D
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CoBB
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Post by CoBB »

Andy_J wrote:jp hl would probably be best... but then again you could have a label called hl... Gah. It's just a crappy mnemonic :D
But this ambiguity isn't resolved, since it's still present in instructions like ld a,(hl).
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Post by Andy_J »

Let's just change assembly into something basic-ish! Or maybe it'd be more like COBOL...

Load into a from the address stored in hl.
Jump to the address stored in hl.
Add 1 to COBOL giving COBOL.


;)
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King Harold
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Post by King Harold »

my worry was actually that it could have been 6 t-states, like LD SP,HL, which is also a 1-byte instruction and a 16bit load to a special-purpose reg16 from hl (opcode: F9, so it could be the same 'family' as jp (hl) with it's opcode E9)
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Jim e
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Post by Jim e »

No it's 4 tstates.
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King Harold
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Post by King Harold »

Ok well I was just giving my reasons for thinking it could have been 6
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Post by King Harold »

recently found this:
(this is from day 25)

Code: Select all

; A = x coordinate
; E = y coordinate     LOOK HERE
; B = number of rows
; IX = address of sprite
    LD     H, 0
    LD     D, H
    LD     E, L          ;AND LOOK HERE
Either E is not the y coordinate or you aren't supposed to overwrite it with L, but this doesn't make much sense.
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tr1p1ea
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Post by tr1p1ea »

Well its probably a typo in the inputs. Other sprite routines (and the code shows) that A would be X and L would be Y.

You should shoot off an email to sigma telling him about this.
"My world is Black & White. But if I blink fast enough, I see it in Grayscale."
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King Harold
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Post by King Harold »

He does have an account on this forum - does he ever check us?
I don't know whether this is worth mailing him for though.. Just a minor typo - and it keeps you sharp while you're reading :P

edit: this is more serious, if it has been noted already then sorry but I'm too lazy to read everything again:
P/V is reset if BC becomes zero. Reset otherwise.
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