| /* ibmpcxt.c: IBM PC Processor simulator |
| |
| Copyright (c) 2016, William A. Beech |
| |
| Permission is hereby granted, free of charge, to any person obtaining a |
| copy of this software and associated documentation files (the "Software"), |
| to deal in the Software without restriction, including without limitation |
| the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| and/or sell copies of the Software, and to permit persons to whom the |
| Software is furnished to do so, subject to the following conditions: |
| |
| The above copyright notice and this permission notice shall be included in |
| all copies or substantial portions of the Software. |
| |
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| WILLIAM A. BEECH BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER |
| IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| |
| Except as contained in this notice, the name of William A. Beech shall not be |
| used in advertising or otherwise to promote the sale, use or other dealings |
| in this Software without prior written authorization from William A. Beech. |
| |
| MODIFICATIONS: |
| |
| 11 Jul 16 - Original file. |
| |
| NOTES: |
| |
| This software was written by Bill Beech, Jul 2016, to allow emulation of IBM PC |
| Computer Systems. |
| */ |
| |
| #include "system_defs.h" |
| |
| int32 nmiflg = 0; //mask NMI off |
| uint8 dmapagreg0, dmapagreg1, dmapagreg2, dmapagreg3; |
| extern uint16 port; //port called in dev_table[port] |
| |
| /* function prototypes */ |
| |
| uint8 get_mbyte(uint32 addr); |
| uint16 get_mword(uint32 addr); |
| void put_mbyte(uint32 addr, uint8 val); |
| void put_mword(uint32 addr, uint16 val); |
| t_stat SBC_reset (DEVICE *dptr); |
| uint8 enbnmi(t_bool io, uint8 data); |
| uint8 dmapag(t_bool io, uint8 data); |
| uint8 dmapag0(t_bool io, uint8 data); |
| uint8 dmapag1(t_bool io, uint8 data); |
| uint8 dmapag2(t_bool io, uint8 data); |
| uint8 dmapag3(t_bool io, uint8 data); |
| |
| /* external function prototypes */ |
| |
| extern t_stat i8088_reset (DEVICE *dptr); /* reset the 8088 emulator */ |
| extern uint8 xtbus_get_mbyte(uint32 addr); |
| extern void xtbus_put_mbyte(uint32 addr, uint8 val); |
| extern uint8 EPROM_get_mbyte(uint32 addr); |
| extern uint8 RAM_get_mbyte(uint32 addr); |
| extern void RAM_put_mbyte(uint32 addr, uint8 val); |
| extern UNIT i8255_unit[]; |
| extern UNIT EPROM_unit; |
| extern UNIT RAM_unit; |
| extern t_stat i8237_reset (DEVICE *dptr, uint16 base); |
| extern t_stat i8253_reset (DEVICE *dptr, uint16 base); |
| extern t_stat i8255_reset (DEVICE *dptr, uint16 base); |
| extern t_stat i8259_reset (DEVICE *dptr, uint16 base); |
| extern t_stat EPROM_reset (DEVICE *dptr, uint32 base, uint32 size); |
| extern t_stat RAM_reset (DEVICE *dptr, uint32 base, uint32 size); |
| extern uint16 reg_dev(uint8 (*routine)(t_bool, uint8), uint16); |
| |
| /* SBC reset routine */ |
| |
| t_stat SBC_reset (DEVICE *dptr) |
| { |
| sim_printf("Initializing IBM PC XT:\n"); |
| i8088_reset (NULL); |
| i8237_reset (NULL, I8237_BASE_0); |
| i8253_reset (NULL, I8253_BASE_0); |
| i8255_reset (NULL, I8255_BASE_0); |
| i8259_reset (NULL, I8259_BASE_0); |
| EPROM_reset (NULL, ROM_BASE, ROM_SIZE); |
| RAM_reset (NULL, RAM_BASE, RAM_SIZE); |
| reg_dev(enbnmi, NMI_BASE); |
| reg_dev(dmapag0, DMAPAG_BASE_0); |
| reg_dev(dmapag1, DMAPAG_BASE_1); |
| reg_dev(dmapag2, DMAPAG_BASE_2); |
| reg_dev(dmapag3, DMAPAG_BASE_3); |
| return SCPE_OK; |
| } |
| |
| uint8 dmapag0(t_bool io, uint8 data) |
| { |
| if (io == 0) { /* read data port */ |
| ; |
| } else { /* write data port */ |
| dmapagreg0 = data; |
| //sim_printf("dmapag0: dmapagreg0=%04X\n", data); |
| } |
| } |
| |
| uint8 dmapag1(t_bool io, uint8 data) |
| { |
| if (io == 0) { /* read data port */ |
| ; |
| } else { /* write data port */ |
| dmapagreg1 = data; |
| //sim_printf("dmapag1: dmapagreg1=%04X\n", data); |
| } |
| } |
| |
| uint8 dmapag2(t_bool io, uint8 data) |
| { |
| if (io == 0) { /* read data port */ |
| ; |
| } else { /* write data port */ |
| dmapagreg2 = data; |
| //sim_printf("dmapag2: dmapagreg2=%04X\n", data); |
| } |
| } |
| |
| uint8 dmapag3(t_bool io, uint8 data) |
| { |
| //sim_printf("dmapag3: entered\n"); |
| if (io == 0) { /* read data port */ |
| ; |
| } else { /* write data port */ |
| dmapagreg3 = data; |
| //sim_printf("dmapag3: dmapagreg3=%04X\n", data); |
| } |
| } |
| |
| uint8 enbnmi(t_bool io, uint8 data) |
| { |
| if (io == 0) { /* read data port */ |
| ; |
| } else { /* write data port */ |
| if (data & 0x80) { |
| nmiflg = 1; |
| //sim_printf("enbnmi: NMI enabled\n"); |
| } else { |
| nmiflg = 0; |
| //sim_printf("enbnmi: NMI disabled\n"); |
| } |
| } |
| } |
| |
| /* get a byte from memory - handle RAM, ROM, I/O, and Multibus memory */ |
| |
| uint8 get_mbyte(uint32 addr) |
| { |
| /* if local EPROM handle it */ |
| if ((addr >= EPROM_unit.u3) && ((uint32)addr < (EPROM_unit.u3 + EPROM_unit.capac))) { |
| return EPROM_get_mbyte(addr); |
| } |
| /* if local RAM handle it */ |
| if ((addr >= RAM_unit.u3) && ((uint16)addr < (RAM_unit.u3 + RAM_unit.capac))) { |
| return RAM_get_mbyte(addr); |
| } |
| /* otherwise, try the multibus */ |
| return xtbus_get_mbyte(addr); |
| } |
| |
| /* get a word from memory */ |
| |
| uint16 get_mword(uint32 addr) |
| { |
| uint16 val; |
| |
| val = get_mbyte(addr); |
| val |= (get_mbyte(addr+1) << 8); |
| return val; |
| } |
| |
| /* put a byte to memory - handle RAM, ROM, I/O, and Multibus memory */ |
| |
| void put_mbyte(uint32 addr, uint8 val) |
| { |
| /* if local EPROM handle it */ |
| if ((addr >= EPROM_unit.u3) && ((uint32)addr <= (EPROM_unit.u3 + EPROM_unit.capac))) { |
| sim_printf("Write to R/O memory address %05X - ignored\n", addr); |
| return; |
| } /* if local RAM handle it */ |
| if ((i8255_unit[0].u5 & 0x02) && (addr >= RAM_unit.u3) && ((uint16)addr <= (RAM_unit.u3 + RAM_unit.capac))) { |
| RAM_put_mbyte(addr, val); |
| return; |
| } /* otherwise, try the multibus */ |
| xtbus_put_mbyte(addr, val); |
| } |
| |
| /* put a word to memory */ |
| |
| void put_mword(uint32 addr, uint16 val) |
| { |
| put_mbyte(addr, val & 0xff); |
| put_mbyte(addr+1, val >> 8); |
| } |
| |
| /* end of ibmpcxt.c */ |