24 lines
911 B
C
24 lines
911 B
C
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/*
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* reset-gen — power-on reset + control-line pull-ups for a Z80 bus computer
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* (Phase 3, project/multichip-bus/). Holds RESET low at power-on, then drives
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* it HIGH after ~2 ms (a rising edge that releases the CPU). Ties WAIT, BUSREQ,
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* INT and NMI high (deasserted) so the CPU runs freely. Lets a multi-chip Z80
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* machine boot on its own when the user clicks Run.
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*/
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#include "velxio-chip.h"
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static vx_pin reset_;
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static vx_timer t;
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static void release(void* ud) { (void)ud; vx_pin_write(reset_, 1); }
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void chip_setup(void) {
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reset_ = vx_pin_register("RESET", VX_OUTPUT_LOW); /* hold CPU in reset */
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vx_pin_register("WAIT", VX_OUTPUT_HIGH);
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vx_pin_register("BUSREQ", VX_OUTPUT_HIGH);
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vx_pin_register("INT", VX_OUTPUT_HIGH);
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vx_pin_register("NMI", VX_OUTPUT_HIGH);
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t = vx_timer_create(release, 0);
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vx_timer_start(t, 2000000ULL, false); /* one-shot, ~2 ms */
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}
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