Difference between revisions of "83Plus:BCALLs:4F54"
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Registers A and C are destroyed to restore the page located in [[83Plus:Ports:06|bank A]] after this call completes. | Registers A and C are destroyed to restore the page located in [[83Plus:Ports:06|bank A]] after this call completes. | ||
| − | In theory, it works for any ROM or RAM page, but | + | In theory, it works for any ROM or RAM page, but will fail if passed A=0. The OS uses it to quickly read a byte from Flash ROM. |
== Example == | == Example == | ||
Latest revision as of 21:20, 25 December 2006
Synopsis
Unofficial Name: GetBytePaged
BCALL Address: 4F54
Gets a byte from a specific page and address.
Inputs
- HL = offset into page where byte is located (4000h-7FFFh).
- A = page where byte is located.
Outputs
- B = byte.
Destroys
- A, C
Notes
Registers A and C are destroyed to restore the page located in bank A after this call completes.
In theory, it works for any ROM or RAM page, but will fail if passed A=0. The OS uses it to quickly read a byte from Flash ROM.
Example
Get first byte of page 03h:
ld a,03h ld hl,4000h B_CALL GetBytePaged ;B contains byte
