Eshs
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Revision as of 02:45, 16 September 2020
Contents |
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.
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0xF1 | In | Control panel input. Only lower 6 data bits are used. Active low.
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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.
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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.