193 lines
7.7 KiB
C
193 lines
7.7 KiB
C
/* mem.c: Intel memory simulator
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Copyright (c) 2020, William A. Beech
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this software and associated documentation files (the "Software"),
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to deal in the Software without restriction, including without limitation
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the rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom the
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Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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WILLIAM A. BEECH BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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Except as contained in this notice, the name of William A. Beech shall not be
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used in advertising or otherwise to promote the sale, use or other dealings
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in this Software without prior written authorization from William A. Beech.
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23 Nov 20 - Original file.
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*/
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#include "system_defs.h"
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/* function prototypes */
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uint8 get_mbyte(uint16 addr);
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uint16 get_mword(uint16 addr);
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void put_mbyte(uint16 addr, uint8 val);
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void put_mword(uint16 addr, uint16 val);
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/* external function prototypes */
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extern uint8 multibus_get_mbyte(uint16 addr);
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extern void multibus_put_mbyte(uint16 addr, uint8 val);
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extern uint8 EPROM_get_mbyte(uint16 addr, uint8 devnum);
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extern UNIT EPROM_unit[];
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extern uint8 RAM_get_mbyte(uint16 addr);
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extern void RAM_put_mbyte(uint16 addr, uint8 val);
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extern UNIT RAM_unit[];
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extern int mem_map;
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extern uint8 monitor_boot;
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/* globals */
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/* extern globals */
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extern uint16 PCX; /* program counter */
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extern uint8 xack; /* XACK signal */
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extern UNIT i8255_unit; //for isbc memory control
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extern UNIT ipc_cont_unit;
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extern UNIT ioc_cont_unit;
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extern uint8 i8255_C[4]; //port C byte I/O
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/* get a byte from memory - handle MODEL, RAM, ROM and Multibus memory */
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uint8 get_mbyte(uint16 addr)
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{
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uint8 val;
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SET_XACK(0); /* clear xack */
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if ((mem_map <= 1) && (addr >= 0xF800)) { //monitor ROM - always there IPB/IPC
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SET_XACK(1); //set xack
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return EPROM_get_mbyte(addr - 0xF000, 0); //top half of EPROM
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}
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if ((mem_map <= 1) && (addr < 0x1000) && ((ipc_cont_unit.u3 & 0x04) == 0)) { //startup IPB/IPC
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SET_XACK(1); //set xack
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return EPROM_get_mbyte(addr, 0); //top half of EPROM for boot
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}
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if ((mem_map <= 1) && (addr >= 0xE800) && (addr < 0xF000) && ((ipc_cont_unit.u3 & 0x10) == 0)) { //diagnostic ROM IPB/IPC
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SET_XACK(1); //set xack
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return EPROM_get_mbyte(addr - 0xE800, 0); //bottom half of EPROM
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}
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if (mem_map == 1) { //IPC RAM
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SET_XACK(1); //set xack
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return RAM_get_mbyte(addr);
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}
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if ((mem_map == 0) && (addr < 0x8000)) { //IPB RAM
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SET_XACK(1); //set xack
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return RAM_get_mbyte(addr);
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}
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if (mem_map == 2) { //800
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if (((monitor_boot & 0x04) == 0) && (addr >= EPROM_unit[0].u3) && (addr <= (EPROM_unit[0].u3 + EPROM_unit[0].capac)))
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return EPROM_get_mbyte(addr, 0);
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else if ((addr >= EPROM_unit[1].u3) && (addr <= (EPROM_unit[1].u3 + EPROM_unit[1].capac)))
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return EPROM_get_mbyte(addr, 1);
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}
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if (mem_map == 3) { //isdk80
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if ((addr >= EPROM_unit->u3) && ((uint16)addr <= (EPROM_unit->u3 + EPROM_unit->capac))) {
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return EPROM_get_mbyte(addr, 0);
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} /* if local RAM handle it */
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else if ((addr >= RAM_unit->u3) && ((uint16)addr <= (RAM_unit->u3 + RAM_unit->capac))) {
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return RAM_get_mbyte(addr);
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}
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else return 0xff;
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}
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if (mem_map == 4) { //isys80/XX
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/* if local EPROM handle it */
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if (i8255_C[0] & 0x80) { /* EPROM enabled */
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if ((addr >= EPROM_unit->u3) && ((uint16)addr <= (EPROM_unit->u3 + EPROM_unit->capac))) {
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val = EPROM_get_mbyte(addr, 0);
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return val;
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}
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} /* if local RAM handle it */
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if (i8255_C[0] & 0x20) { /* RAM enabled */
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if ((addr >= RAM_unit->u3) && ((uint16)addr <= (RAM_unit->u3 + RAM_unit->capac))) {
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val = RAM_get_mbyte(addr);
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return val;
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}
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} /* otherwise, try the multibus */
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}
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return multibus_get_mbyte(addr); //check multibus cards
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}
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/* get a word from memory */
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uint16 get_mword(uint16 addr)
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{
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uint16 val;
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val = get_mbyte(addr);
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val |= (get_mbyte(addr+1) << 8);
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return val;
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}
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/* put a byte to memory - handle RAM, ROM and Multibus memory */
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void put_mbyte(uint16 addr, uint8 val)
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{
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SET_XACK(0); /* set no XACK */
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if (addr >= 0xF800) { //monitor ROM - always there IPB/IPC/800
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return; //do nothing
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}
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if ((mem_map <= 1) && (addr < 0x1000) && ((ipc_cont_unit.u3 & 0x04) == 0)) { //startup IPB/IPC
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return; //do nothing
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}
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if ((mem_map <= 1) && (addr >= 0xE800) && (addr < 0xF000) && ((ipc_cont_unit.u3 & 0x10) == 0)) { //diagnostic ROM IPB/IPC
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return; //do nothing
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}
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if (mem_map == 1) { //IPC RAM
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SET_XACK(1); //set xack
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RAM_put_mbyte(addr, val); //IPCRAM
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return;
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}
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if ((mem_map == 0) && (addr < 0x8000)) { //IPB RAM
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SET_XACK(1); //set xack
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RAM_put_mbyte(addr, val); //IPB RAM
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return;
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}
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if (mem_map == 3) { //isdk80
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/* if local EPROM handle it */
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if ((addr >= EPROM_unit->u3) && ((uint16)addr <= (EPROM_unit->u3 + EPROM_unit->capac))) {
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sim_printf("Write to R/O memory address %04X from PC=%04X - ignored\n", addr, PCX);
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return;
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} /* if local RAM handle it */
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if ((addr >= RAM_unit->u3) && ((uint16)addr <= (RAM_unit->u3 + RAM_unit->capac))) {
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RAM_put_mbyte(addr, val);
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return;
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}
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}
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if (mem_map == 4) { //isys80/xx
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/* if local EPROM handle it */
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if (i8255_C[0] & 0x80) { /* EPROM enabled */
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if ((addr >= EPROM_unit->u3) && ((uint16)addr <= (EPROM_unit->u3 + EPROM_unit->capac))) {
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sim_printf("Write to R/O memory address %04X from PC=%04X - ignored\n", addr, PCX);
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return;
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}
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} /* if local RAM handle it */
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if (i8255_C[0] & 0x20) { /* RAM enabled */
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if ((addr >= RAM_unit->u3) && ((uint16)addr <= (RAM_unit->u3 + RAM_unit->capac))) {
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RAM_put_mbyte(addr, val);
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return;
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}
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} /* otherwise, try the multibus */
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}
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multibus_put_mbyte(addr, val); //check multibus cards
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}
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/* put a word to memory */
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void put_mword(uint16 addr, uint16 val)
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{
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put_mbyte(addr, val & 0xff);
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put_mbyte(addr+1, val >> 8);
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}
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/* end of mem.c */
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