Peripheral 3 Setting Register: Difference between revisions
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m Xalior moved page Peripheral 3 Register to Peripheral 3 Setting Register: match formal nextreg.txt name |
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|Readable=Yes | |Readable=Yes | ||
|Writable=Yes | |Writable=Yes | ||
|ShortDesc= | |ShortDesc=ABC/ACB [[Stereo]], Internal Speaker, [[SpecDrum]], [[Enhanced ULA|Timex Video Modes]], [[Turbo Sound Next]], RAM contention and [un]lock 128k paging. | ||
}} | }} | ||
(R/W) 0x08 (08) => Peripheral 3 setting: | |||
bit 7 = Unlock(1)/lock(0) port $7FFD paging (read 1 indicates port $7FFD is not locked) | |||
bit 6 = 1 to disable RAM and I/O port contention (soft reset = 0) | |||
bit 5 = AY stereo mode (0 = ABC, 1 = ACB) (hard reset = 0) | |||
bit 4 = Enable internal speaker (hard reset = 1) | |||
bit 3 = Enable 8-bit DACs (A,B,C,D) (hard reset = 0) | |||
bit 2 = Enable port $FF Timex video mode *read* (hides floating bus on 0xff) (hard reset = 0) | |||
bit 1 = Enable Turbosound (currently selected AY is frozen when disabled) (hard reset = 0) | |||
bit 0 = Implement Issue 2 keyboard (port $FE reads as early ZX boards) (hard reset = 0) | |||
The Timex modes are operational even when bit 2 is set to zero, you can still write to port $FF with desired mode changes. Bit 2 does only enable readability of port $FF. | |||
When loading 48k SNA files through NextZXOS, be aware it does lock down many features of Next to better simulate ZX48 machine, including lock of {{PortNo|$7FFD}} paging feature. If you are using 48k SNA file for convenience, but you are actually using full ZX Next features, make sure you enable/unlock all relevant bits, before using the particular feature. | |||
Latest revision as of 14:47, 13 October 2025
| Number | TBRegisterNumber::$08 |
|---|---|
| Readable | TBRegisterReadable::Yes |
| Writable | TBRegisterWritable::Yes |
| Short Description | [[ShortDesc::ABC/ACB Stereo, Internal Speaker, SpecDrum, Timex Video Modes, Turbo Sound Next, RAM contention and [un]lock 128k paging.]] |
(R/W) 0x08 (08) => Peripheral 3 setting:
bit 7 = Unlock(1)/lock(0) port $7FFD paging (read 1 indicates port $7FFD is not locked) bit 6 = 1 to disable RAM and I/O port contention (soft reset = 0) bit 5 = AY stereo mode (0 = ABC, 1 = ACB) (hard reset = 0) bit 4 = Enable internal speaker (hard reset = 1) bit 3 = Enable 8-bit DACs (A,B,C,D) (hard reset = 0) bit 2 = Enable port $FF Timex video mode *read* (hides floating bus on 0xff) (hard reset = 0) bit 1 = Enable Turbosound (currently selected AY is frozen when disabled) (hard reset = 0) bit 0 = Implement Issue 2 keyboard (port $FE reads as early ZX boards) (hard reset = 0)
The Timex modes are operational even when bit 2 is set to zero, you can still write to port $FF with desired mode changes. Bit 2 does only enable readability of port $FF.
When loading 48k SNA files through NextZXOS, be aware it does lock down many features of Next to better simulate ZX48 machine, including lock of {{#ask: PortNumber::$7FFD }} ($7FFD{{#ask: PortNumber::$7FFD |mainlabel=- |headers=hide |intro= / |?NumberDec#- }}) paging feature. If you are using 48k SNA file for convenience, but you are actually using full ZX Next features, make sure you enable/unlock all relevant bits, before using the particular feature.