Requiered a BIOS call for INT from timer in MSX1 and MSX2

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By sp4

Master (214)

sp4의 아바타

25-07-2011, 20:23

Hi, i want know what is the BIOS call in MSX1 and MSX2 and the function (or the address) of reply about the INTERRUPT from timer in these two machines.
Nobody can help me to know how is make the INTERRUPT from timer in MSX1 and MSX2 ?
Thanks very muck for the help.

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By Manuel

Ascended (19273)

Manuel의 아바타

25-07-2011, 21:01

What exactly do you mean?

By pitpan

Prophet (3155)

pitpan의 아바타

25-07-2011, 22:35

If you want to make it MSX1 compatible, you should use v-blank interruption (every 50th/60th of a second). To do so, you should acknowledge the interrupt and/or hook HTIMI o similar. Enjoy.

By sp4

Master (214)

sp4의 아바타

26-07-2011, 12:48

What's the v-blank interruption?
Can you explain more exactly the v-bank interruption?

By sp4

Master (214)

sp4의 아바타

26-07-2011, 12:54

I' want know if there is a BIOS call for manage the interrupt from counter, and i want know
what's the function of reply of that INTERRUPT.
Have you understand?

By pitpan

Prophet (3155)

pitpan의 아바타

27-07-2011, 10:10

Not really, I'm sorry. I'm not following your question. In any case:

xor a
ei
LOOP:
halt
inc a
jr LOOP

This code will increase the A register every 50th or 60th of a second. The "HALT" will effectively halt the computer until the vertical retrace interruption (in the best case scenario) is acknowledged. So, if you want a timer, start coding from here.

By ro

Scribe (4902)

ro의 아바타

27-07-2011, 11:58

ServicePack4: it could be the language barrier that's making your question unclear to us poor souls.
bij default: Whenever MSX generated an interrupt (no matter the source) it "jumps" to address #38. If you have ROM enabled on page 0 (000-3fff) you'll find the defautl interrupt handler routine. It does keyboard mapping, counters and a call to the "hook" (fd9a or fd9f, depending on the source of the interrupt) pitpan mentioned.

disassemble #00038 if you like to see whaz-up.

does that answer ye question, hombre?

By ro

Scribe (4902)

ro의 아바타

27-07-2011, 12:00

oh, and 'v-blank' is short for vertical-blank. It's the interrupt generated at the end of the screen (refresh). So every 50th or 60th (depending on your refresh rate) of a second it'll CALL to #38.

By sp4

Master (214)

sp4의 아바타

27-07-2011, 14:00

Thank yuo for your help.
In your reply you tell about ROM enable in page 0. What can I enable this ROM enable?
Are the locations from #00038 address empty or are busy with the default ROM routine?
Can you specify well that detail please?

By sp4

Master (214)

sp4의 아바타

27-07-2011, 14:07

Pitpan: does the timer inside the Video Controller connected with the HALT wire of the Z80?

By ro

Scribe (4902)

ro의 아바타

27-07-2011, 14:14

SP4, what's your assembly knowledge skill?

I'm asking 'cuz you ask about some basic-knowledge for asm programmers and it makes me wonder what the heck you want to achieve. are you gonna do some asm coding ?

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