Eshs

(Difference between revisions)

Revision as of 20:28, 17 August 2020

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
0xF000-0xF7FF	Unknown (Daphne says that this is video hardware)

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?
0xF8	Out	0 disables start button lamp. 1 enables.
0xFA	Out	0 disables action button lamp. 1 enables.
0xFB	Out	0 disables joystick lamp. 1 enables.
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 be triggered normally.
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 be triggered normally.

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.

@@ Line 72: / Line 72: @@
 |0xFE
 |Out
-|0 forces IRQ' line to be high (disabled).  1 allows IRQs to be triggered normally.
+|0 holds IRQ' line high (disabled) by forcing a latch to be clear.  1 stops forcing latch to be clear, which allows IRQs to be triggered normally.
 |-
 |0xFF
 |Out
-|0 forces NMI' line to be high (disabled).  1 allows NMIs to be triggered normally.
+|0 holds NMI' line high (disabled) by forcing a latch to be clear.  1 stops forcing latch to be clear, which allows NMIs to be triggered normally.
 |-