Eshs

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Revision as of 22:16, 11 September 2020 (view source) Matt (Talk | contribs) m (added PROM section) ← Older edit		Revision as of 02:45, 16 September 2020 (view source) Matt (Talk | contribs) m (→Z80 Port Map) Newer edit →
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	|'''Bit'''		|'''Bit'''
	|'''Description'''		|'''Description'''
		+	|-
		+	|0
		+	|Not connected
	|-		|-
	|1		|1

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Revision as of 02:45, 16 September 2020

Contents 1 Esh's Aurunmilla 1.1 Memory Map 1.2 Z80 Port Map 1.3 Z80 Interrupts 1.4 Video RAM Structure 1.5 PROM replacements

Esh's Aurunmilla

Memory Map

Address Range	Description
0x0000-0x1FFF	ROM H8
0x2000-0x3FFF	ROM F8
0x4000-053FFF	ROM E8
0x6000-073FFF	ROM D8
0x8000-0x9FFF	ROM C8
0xE000-0xE7FF	CPU RAM (B8)
0xF000-0xF7FF	Video RAM (F3)

Z80 Port Map

Address Range	Direction	Description
0xF0	In	Control panel input. Only lower 6 data bits are used. Active low. Bit Description 0 COIN 1 1 COIN 2 2 START 1 3 ? (start 2? unconfirmed) 4 TEST
0xF1	In	Control panel input. Only lower 6 data bits are used. Active low. Bit Description 0 UP 1 DOWN 2 LEFT 3 RIGHT 4 ACTION BUTTON
0xF2	In	Control panel input. Only lower 6 data bits are used.
0xF3	In	Control panel input. Only lower 6 data bits are used.
0xF4	In/Out	LD-V1000 data. Writing queues a command to be sent on the next command strobe. Reading reads the most recent byte received during last the status strobe.
0xF5	Out	Misc value. Bit Description 0 Not connected 1 is audio (1 = audio signal comes from a vertical counter (VA3), 0 = audio signal is low). 2,3 Bit 2 and 3 deal with whether to show the laserdisc image or not. If bit 3 is high, A7 of the RGB prom is also high, laserdisc video is suppressed, and bit 2 is ignored. If bit 2 is high (and bit 3 is low) A7 of the RGB prom is low, and laserdisc video is suppressed. 4-7 Bits 4-7 appear to decide whether A8 of the RGB prom is high/low depending on current position. This may be a way to have different pixels of a tile use a different color palette.
0xF8	Out	0 disables start button lamp. 1 enables.
0xF9	Out	Drives EDGE_06 (on the edge connector), but we don't know what this is connected to.
0xFA	Out	0 disables action button lamp. 1 enables.
0xFB	Out	0 disables joystick lamp. 1 enables.
0xFC	Out	Not connected
0xFD	Out	Not connected
0xFE	Out	0 holds IRQ' line high (disabled) by forcing a latch to be clear. 1 stops forcing latch to be clear, which allows IRQs to set the latch.
0xFF	Out	0 holds NMI' line high (disabled) by forcing a latch to be clear. 1 stops forcing latch to be clear, which allows NMIs to set the latch.

Z80 Interrupts

NMI: Caused by LD-V1000 status strobe going low (becoming active)

IRQ: Caused by D2 output (pin 10) on vertical PROM (C6) transitioning from 0 to 1. This ends up being 60 Hz (vsync).

Video RAM Structure

Screen is divided into 32x32 tiles. The first tile is the top left.

0xF000-0xF3FF contain which tile to show.

0xF400-0xF7FF contain tile attributes. For example, 0xF400 would have attributes about the tile index at 0xF000.

PROM replacements

H and V PROMs are MB7052. MB7052 are compatible with 82s129 proms. One option is http://callanbrown.com/index.php/flep-prom-replacement-adapters

RGB PROM is MB7124. MB7124 are compatible with 82s147 proms. Haven't found replacement yet.

Newer EEPROMs may be fast enough. W27C512 may be a commonly available EEPROM.