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1 line
3.3 KiB
Plaintext
1 line
3.3 KiB
Plaintext
;********* biosif.8kn for cpm.sys + cpmldr.sys *******
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;* Copyright 1984, Digital Research Inc.
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;*
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;* Assembly language interface for CP/M-8000(tm) BIOS
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;* ----- System-Independent -----
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;*
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;* 821013 S. Savitzky (Zilog) -- split into modules
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;* 820913 S. Savitzky (Zilog) -- created.
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;* 840811 R. Weiser (DRI) -- conditional assembly
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;*
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__text: .sect
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;****************************************************
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;*
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;* NOTE
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;* The C portion of the BIOS is non-segmented.
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;*
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;* This assembly-language module is assembled
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;* non-segmented, and serves as the interface.
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;*
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;* Segmented operations are well-isolated, and
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;* are either the same as their non-segmented
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;* counterparts, or constructed using macros.
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;* The resulting code looks a little odd.
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;*
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;****************************************************
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;****************************************************
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;*
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;* Externals
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;*
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;****************************************************
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.global _biosinit ;C portion init
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.if LOADER ; If LOADER is True then
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.global _ldcpm ; Load the system into memory
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.else ; else its the normal bios
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.global _flush ;Flush buffers
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.global ccp ;Command Processor
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.endif ; end conditional
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.global _trapinit ;trap startup
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.global _psap, _sysseg, _sysstk
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;****************************************************
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;*
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;* Global declarations
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;*
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;****************************************************
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.global bios ; initialization
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.if LOADER ; If Loader stub out _wboot
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.else
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.global _wboot ; warm boot
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.endif
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.global _input ; input a byte
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.global _output ; output a byte
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;****************************************************
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;*
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;* Bios Initialization and Entry Point
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;*
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;* This is where control comes after boot.
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;* If (the label LOADER is true 1)
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;* Control is transferred to -ldcpm
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;* else
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;* Control is transferred to the ccp.
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;*
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;* We get here from bootstrap with:
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;* segmented mode
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;* valid stack pointer
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;* valid PSA in RAM
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;*
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;****************************************************
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bios:
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; enter in segmented mode.
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; Get system (PC) segment into r4
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DI VI,NVI
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calr kludge ; get PC segment on stack
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kludge: popl rr4, @r14
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; get PSAP into rr2.
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ldctl r2, PSAPSEG
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ldctl r3, PSAPOFF
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; go non-segmented. save PSAP, system segment,
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; system stack pointer (in system segment, please)
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NONSEG
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ldl _psap, rr2
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ld _sysseg, r4
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ld r14,_sysseg
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ldl _sysstk, rr14
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.if LOADER
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.else
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; set up system stack so that a return will warm boot
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push @r15,#_wboot
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.endif
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; set up traps, then enable interrupts
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call _trapinit
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EI VI,NVI
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; set up C part of Bios
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call _biosinit
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; Turn control over to command processor
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.if LOADER
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jp _ldcpm ; do Program load
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.else
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jp ccp
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;*****************************************************
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;*
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;* Warm Boot
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;*
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;* flush buffers and initialize Bios
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;* then transfer to CCP
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;*
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;*****************************************************
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_wboot:
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call _flush
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call _biosinit
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ldl rr14,_sysstk
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jp ccp
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.endif
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;****************************************************
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;*
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;* I/O port operations
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;*
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;* int = input(port: int)
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;* output (port, data: int)
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;*
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;****************************************************
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_input:
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ld r2,ARG1(r15)
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subl rr6,rr6
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inb rl7,@r2
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ldb rl6,rl7
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ret
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_output:
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ld r2,ARG1(r15)
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ld r3,ARG2(r15)
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outb @r2,rl3
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ret
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;*****************************************************
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;*****************************************************
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******
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