Ped7g: core 3.1.3 changes/refresh

2020-04-13T19:02:05Z

core 3.1.3 changes/refresh

← Older revision		Revision as of 20:02, 13 April 2020
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	All bits are set to 1 upon hard reset.		since core3.1.1: all bits are set to 1 when: soft reset and bit 31 is clear OR hard reset and bit 31 is set (otherwise content is kept intact). <del>All bits are set to 1 upon hard reset.</del>

	When the expansion bus is on, the expansion port decoding mask (Next Registers $86-$89) is logically ANDed with the internal enables (Next Registers $82-$85). A zero bit indicates the internal device is disabled.		When the expansion bus is on, the expansion port decoding mask (Next Registers $86-$89) is logically ANDed with the internal enables (Next Registers $82-$85). A zero bit indicates the internal device is disabled.

Ped7g: core 3.0 changes/refresh

2019-11-12T09:39:05Z

core 3.0 changes/refresh

New page

{{NextRegister
|Number=$86
|Readable=Yes
|Writable=Yes
|ShortDesc=When expansion bus is enabled: Internal ports decoding mask
}}
{|class="wikitable"
! Bit !! Description
|-
| 7 || Masking decoding: {{PortNo|$xx37}} (also MD2 controller)
|-
| 6 || Masking decoding: {{PortNo|$xx1F}} (also MD1 controller)
|-
| 5 || Masking decoding: {{PortNo|$xx6B}}
|-
| 4 || Masking decoding: +3 floating bus
|-
| 3 || Masking decoding: {{PortNo|$1FFD}}
|-
| 2 || Masking decoding: {{PortNo|$DFFD}}
|-
| 1 || Masking decoding: {{PortNo|$7FFD}}
|-
| 0 || Masking decoding: {{PortNo|$xxFF}}
|}

All bits are set to 1 upon hard reset.

When the expansion bus is on, the expansion port decoding mask (Next Registers $86-$89) is logically ANDed with the internal enables (Next Registers $82-$85). A zero bit indicates the internal device is disabled.

If the expansion bus is on, this allows I/O cycles for disabled internal ports to propagate to the expansion bus, otherwise corresponding I/O cycles to the expansion bus are filtered.

(note: Next registers with number higher than $7F are inaccessible from Copper code)

Expansion Bus Decoding b0-7 Register - Revision history

Ped7g: core 3.1.3 changes/refresh

Ped7g: core 3.0 changes/refresh