izapple2/cardThunderClockPlus.go

package izapple2

import "github.com/ivanizag/izapple2/component"

/*
ThunderClock`, real time clock card.

See:
	https://ia800706.us.archive.org/22/items/ThunderClock_Plus/ThunderClock_Plus.pdf
	https://prodos8.com/docs/technote/01/
	https://www.semiee.com/file/backup/NEC-D1990.pdf


uPD1990AC hookup:
	bit 0 = data in
	bit 1 = CLK
	bit 2 = STB
	bit 3 = C0
	bit 4 = C1
	bit 5 = C2
	bit 7 = data out
*/

// CardThunderClockPlus represents a ThunderClock+ card
type CardThunderClockPlus struct {
	cardBase
	upd1990 component.MicroPD1990ac
}

func newCardThunderClockPlusBuilder() *cardBuilder {
	return &cardBuilder{
		name:        "ThunderClock+ Card",
		description: "Clock card",
		buildFunc: func(params map[string]string) (Card, error) {
			var c CardThunderClockPlus
			err := c.loadRomFromResource("<internal>/ThunderclockPlusROM.bin", cardRomUpper)
			if err != nil {
				return nil, err
			}
			return &c, nil
		},
	}
}

func (c *CardThunderClockPlus) assign(a *Apple2, slot int) {
	c.addCardSoftSwitchR(0, func() uint8 {
		bit := c.upd1990.Out()
		// Get the next data bit from uPD1990AC on the MSB
		if bit {
			return 0x80
		}
		return 0
	}, "THUNDERCLOCKR")

	c.addCardSoftSwitchW(0, func(value uint8) {
		dataIn := (value & 0x01) == 1
		clock := ((value >> 1) & 0x01) == 1
		strobe := ((value >> 2) & 0x01) == 1
		command := (value >> 3) & 0x07
		/* fmt.Printf("[cardThunderClock] dataIn %v, clock %v, strobe %v, command %v.\n",
		dataIn, clock, strobe, command) */

		c.upd1990.In(clock, strobe, command, dataIn)
	}, "THUNDERCLOCKW")

	c.cardBase.assign(a, slot)
}