Eshs

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(Memory Map)
(Z80 Port Map)
Line 56: Line 56:
|0xF5
|0xF5
|Out
|Out
-
|Misc value?
+
|Misc value.  Bit 1 is audio (1 = audio signal comes from a vertical counter (VA3), 0 = audio signal is low).  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.  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
|0xF8
|Out
|Out
|0 disables start button lamp.  1 enables.
|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
|0xFA
Line 69: Line 73:
|Out
|Out
|0 disables joystick lamp.  1 enables.
|0 disables joystick lamp.  1 enables.
 +
|-
 +
|0xFC
 +
|Out
 +
|Not connected
 +
|-
 +
|0xFD
 +
|Out
 +
|Not connected
|-
|-
|0xFE
|0xFE

Revision as of 20:25, 18 August 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.
0xF1 In Control panel input. Only lower 6 data bits are used.
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 1 is audio (1 = audio signal comes from a vertical counter (VA3), 0 = audio signal is low). 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. 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.

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.

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