Difference between revisions of "InstallRAMISR"
From MSX Game Library
(Created page with "This Build tool option allow cartridge program to use page #0 (address 0000h~3FFFh) as RAM. This gives almost 16 KB more memory. If <tt>InstallRAMISR</tt> is set to 1, th...") |
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This [[Build tool]] option allow cartridge program to use page #0 (address 0000h~3FFFh) as RAM. This gives almost 16 KB more memory. | This [[Build tool]] option allow cartridge program to use page #0 (address 0000h~3FFFh) as RAM. This gives almost 16 KB more memory. | ||
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| + | :: Set RAM in slot 0 and install ISR there (0=false, 1=true) | ||
| + | set InstallRAMISR=0 | ||
If <tt>InstallRAMISR</tt> is set to 1, the cartridge boot code will automatically switch page #0 to the same slot as page #3 (where RAM is located), then copy a ISR (Interrupt Service Routine) at address 0038h. This ISR handle VDP's V-Blank interruption (each 50/60 Hz) and call an handler function that program must provide: <tt>void VDP_InterruptHandler();</tt> | If <tt>InstallRAMISR</tt> is set to 1, the cartridge boot code will automatically switch page #0 to the same slot as page #3 (where RAM is located), then copy a ISR (Interrupt Service Routine) at address 0038h. This ISR handle VDP's V-Blank interruption (each 50/60 Hz) and call an handler function that program must provide: <tt>void VDP_InterruptHandler();</tt> | ||
Revision as of 23:54, 8 June 2022
This Build tool option allow cartridge program to use page #0 (address 0000h~3FFFh) as RAM. This gives almost 16 KB more memory.
:: Set RAM in slot 0 and install ISR there (0=false, 1=true) set InstallRAMISR=0
If InstallRAMISR is set to 1, the cartridge boot code will automatically switch page #0 to the same slot as page #3 (where RAM is located), then copy a ISR (Interrupt Service Routine) at address 0038h. This ISR handle VDP's V-Blank interruption (each 50/60 Hz) and call an handler function that program must provide: void VDP_InterruptHandler();
Warnings:
- This option only work on MSX with at least 64 KB of RAM (otherwise, there is no RAM on page #0).
- Obviously, no BIOS function can be used in this program (unless you reswitched the Main-ROM on page #0 first).