148 lines
5.1 KiB
C
148 lines
5.1 KiB
C
/* pdp8_tsc.c: PDP-8 ETOS timesharing option board (TSC8-75)
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Copyright (c) 2003-2011, Robert M Supnik
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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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ROBERT M SUPNIK 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 Robert M Supnik 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 Robert M Supnik.
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This module is based on Bernhard Baehr's description of the TSC8-75's
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operation. Many thanks to Bernhard for figuring out the behavior of this
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undocumented device.
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tsc TSC8-75 option board
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*/
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#include "pdp8_defs.h"
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extern int32 int_req;
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extern int32 SF;
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extern int32 tsc_ir; /* "ERIOT" */
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extern int32 tsc_pc; /* "ERTB" */
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extern int32 tsc_cdf; /* "ECDF" */
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extern int32 tsc_enb; /* enable */
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#define UNIT_V_SN699 (UNIT_V_UF + 0) /* SN 699 or above */
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#define UNIT_SN699 (1 << UNIT_V_SN699)
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int32 tsc (int32 IR, int32 AC);
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t_stat tsc_reset (DEVICE *dptr);
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const char *tsc_description (DEVICE *dptr);
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/* TSC data structures
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tsc_dev TSC device descriptor
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tsc_unit TSC unit descriptor
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tsc_reg TSC register list
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*/
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DIB tsc_dib = { DEV_TSC, 1, { &tsc } };
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UNIT tsc_unit = { UDATA (NULL, UNIT_SN699, 0) };
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REG tsc_reg[] = {
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{ ORDATAD (IR, tsc_ir, 12, "most recently trapped instruction") },
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{ ORDATAD (PC, tsc_pc, 12, "PC of most recently trapped instruction") },
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{ FLDATAD (CDF, tsc_cdf, 0, "1 if trapped instruction is CDF, 0 otherwise") },
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{ FLDATAD (ENB, tsc_enb, 0, "interrupt enable flag") },
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{ FLDATAD (INT, int_req, INT_V_TSC, "interrupt pending flag") },
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{ NULL }
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};
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MTAB tsc_mod[] = {
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{ UNIT_SN699, UNIT_SN699, "ESME", "ESME", NULL },
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{ UNIT_SN699, 0, "no ESME", "NOESME", NULL },
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{ 0 }
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};
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DEVICE tsc_dev = {
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"TSC", &tsc_unit, tsc_reg, tsc_mod,
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1, 10, 31, 1, 8, 8,
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NULL, NULL, &tsc_reset,
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NULL, NULL, NULL,
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&tsc_dib, DEV_DISABLE | DEV_DIS, 0,
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NULL, NULL, NULL, NULL, NULL, NULL,
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&tsc_description
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};
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/* IOT routine */
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int32 tsc (int32 IR, int32 AC)
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{
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switch (IR & 07) { /* decode IR<9:11> */
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case 0: /* ETDS */
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tsc_enb = 0; /* disable int req */
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int_req = int_req & ~INT_TSC; /* clear flag */
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break;
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case 1: /* ESKP */
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return (int_req & INT_TSC)? IOT_SKP + AC: AC; /* skip on int req */
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case 2: /* ECTF */
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int_req = int_req & ~INT_TSC; /* clear int req */
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break;
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case 3: /* ECDF */
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AC = AC | ((tsc_ir >> 3) & 07); /* read "ERIOT"<6:8> */
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if (tsc_cdf) /* if cdf, skip */
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AC = AC | IOT_SKP;
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tsc_cdf = 0;
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break;
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case 4: /* ERTB */
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return tsc_pc;
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case 5: /* ESME */
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if (tsc_unit.flags & UNIT_SN699) { /* enabled? */
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if (tsc_cdf && ((tsc_ir & 070) >> 3) == (SF & 07)) {
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AC = AC | IOT_SKP;
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tsc_cdf = 0;
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}
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}
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break;
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case 6: /* ERIOT */
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return tsc_ir;
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case 7: /* ETEN */
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tsc_enb = 1;
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break;
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} /* end switch */
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return AC;
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}
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/* Reset routine */
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t_stat tsc_reset (DEVICE *dptr)
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{
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tsc_ir = 0;
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tsc_pc = 0;
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tsc_cdf = 0;
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tsc_enb = 0;
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int_req = int_req & ~INT_TSC;
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return SCPE_OK;
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}
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const char *tsc_description (DEVICE *dptr)
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{
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return "TSC8-75 option board";
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}
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