Sega Master System II: Difference between revisions
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| weight = ≈ 0.8 kg | | weight = ≈ 0.8 kg | ||
| os = None – game ROM executes directly | | os = None – game ROM executes directly | ||
| predecessor = [[Sega Master System | | predecessor = [[Sega Master System (Model 1)]] | ||
| successor = [[Sega_Mega_Drive_(Model_1)|Mega Drive / Genesis]] | | successor = [[Sega_Mega_Drive_(Model_1)|Mega Drive / Genesis]] | ||
| codename = '''MK-2000''' / '''Model 3000''' | | codename = '''MK-2000''' / '''Model 3000''' | ||
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The '''Sega Master System II''' (SMS II) is a low-cost redesign of Sega’s 8-bit Master System, launched in 1990 to extend the life of the platform alongside the 16-bit Mega Drive. Sega’s engineers removed costly interfaces (card slot, A/V RGB, expansion port) and shrank the PCB to reduce bill-of-materials to under US$40, allowing aggressive pricing against Nintendo’s NES. | The '''Sega Master System II''' (SMS II) is a low-cost redesign of Sega’s 8-bit Master System, launched in 1990 to extend the life of the platform alongside the 16-bit Mega Drive. Sega’s engineers removed costly interfaces (card slot, A/V RGB, expansion port) and shrank the PCB to reduce bill-of-materials to under US$40, allowing aggressive pricing against Nintendo’s NES. | ||
== | == Internal Architecture == | ||
{| class="wikitable styled-table" style="width:70%; text-align:center;" | {| class="wikitable styled-table" style="width:70%; text-align:center;" | ||
! Sub-system !! Specification (Model 3000-07, PAL VA1) | ! Sub-system !! Specification (Model 3000-07, PAL VA1) | ||
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|} | |} | ||
== | == Z80 Memory Map == | ||
{| class="wikitable styled-table" style="width:70%;" | {| class="wikitable styled-table" style="width:70%;" | ||
|+'''SMS II Address Space''' | |+'''SMS II Address Space''' | ||
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# If BIOS disabled (JP pads), control jumps to cartridge vector <code>$0000</code>. | # If BIOS disabled (JP pads), control jumps to cartridge vector <code>$0000</code>. | ||
== | == Video Modes & Timing == | ||
{| class="wikitable styled-table" style="width:70%; text-align:center;" | {| class="wikitable styled-table" style="width:70%; text-align:center;" | ||
! Region !! Active area !! Master clock !! Lines/frame !! Refresh | ! Region !! Active area !! Master clock !! Lines/frame !! Refresh | ||
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VDP can output composite and RGB; '''SMS II only routes composite + mono audio to an RF modulator''', necessitating A/V modding for RGB. | VDP can output composite and RGB; '''SMS II only routes composite + mono audio to an RF modulator''', necessitating A/V modding for RGB. | ||
== | == Cartridge / Edge Bus (50-pin) == | ||
The SMS II retains the 50-pin “Mega Cartridge” connector used by the original console: | The SMS II retains the 50-pin “Mega Cartridge” connector used by the original console: | ||
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Full table on [[Sega Master System Cartridge Pin-out]]. | Full table on [[Sega Master System Cartridge Pin-out]]. | ||
== | == Historical Context & Sales == | ||
* Announced July 1990 as a cost-reduced successor; included *Alex Kidd* or *Sonic the Hedgehog* in ROM to stimulate sales. | * Announced July 1990 as a cost-reduced successor; included *Alex Kidd* or *Sonic the Hedgehog* in ROM to stimulate sales. | ||
* '''Europe & Brazil''' remained the Master-System strongholds: by 1993 > 6 million SMS II units shipped in EU territories; TecToy sold an additional 2 million (1991-2003). | * '''Europe & Brazil''' remained the Master-System strongholds: by 1993 > 6 million SMS II units shipped in EU territories; TecToy sold an additional 2 million (1991-2003). | ||
* In North America it served as a US$50 budget console beside the Genesis <small>(approx. 300 k units)</small>. | * In North America it served as a US$50 budget console beside the Genesis <small>(approx. 300 k units)</small>. | ||
== | == Motherboard Revisions & Known Errata == | ||
{| class="wikitable styled-table" style="width:85%; text-align:center;" | {| class="wikitable styled-table" style="width:85%; text-align:center;" | ||
! Rev !! ASIC !! Notable features / quirks | ! Rev !! ASIC !! Notable features / quirks | ||
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*Early VA0 boards omit 33 Ω series resistors on RGB lines ⇒ over-driven when modded.* | *Early VA0 boards omit 33 Ω series resistors on RGB lines ⇒ over-driven when modded.* | ||
== | == Audio Path == | ||
Z80 → SN76489 square/noise → low-pass RC (33 k/3.3 nF) → CXA1145 composite encoder → RF can; stereo mods tap pre-RF and split PSG tone channels. | Z80 → SN76489 square/noise → low-pass RC (33 k/3.3 nF) → CXA1145 composite encoder → RF can; stereo mods tap pre-RF and split PSG tone channels. | ||
== | == Common Faults (SMS II) == | ||
* '''No RF / distorted video''' – cracked solder on CXA1145 or corroded RF shield. | * '''No RF / distorted video''' – cracked solder on CXA1145 or corroded RF shield. | ||
* '''Low audio volume / buzzing''' – dried C31 10 µF coupling cap (VA1). | * '''Low audio volume / buzzing''' – dried C31 10 µF coupling cap (VA1). | ||
* '''Power LED flicker''' – 5 V rail ripple; replace 2200 µF filter cap (C8). | * '''Power LED flicker''' – 5 V rail ripple; replace 2200 µF filter cap (C8). | ||
* '''Controller port failures''' – broken traces to 315-5237 I/O decoder. | * '''Controller port failures''' – broken traces to 315-5237 I/O decoder. | ||
Detailed procedures: [[Master System II Troubleshooting Guide]] & [[Master System II Capacitor Replacement Guide]]. | Detailed procedures: [[Sega Master System II Troubleshooting Guide|Master System II Troubleshooting Guide]] & [[Sega Master System II Capacitor Replacement Guide|Master System II Capacitor Replacement Guide]]. | ||
== | == Maintenance & Mods == | ||
* '''Composite/RGB A/V mod:''' lift RF modulator pin 11, route CXA1145 RGB → mini-DIN 8; add 75 Ω/220 µF caps. Step-by-step on [[SMS II AV Output Guide]]. | * '''Composite/RGB A/V mod:''' lift RF modulator pin 11, route CXA1145 RGB → mini-DIN 8; add 75 Ω/220 µF caps. Step-by-step on [[SMS II AV Output Guide]]. | ||
* '''Pause-button cap fix:''' add 100 nF across reset-pause lines to avoid random resets on VA0. | * '''Pause-button cap fix:''' add 100 nF across reset-pause lines to avoid random resets on VA0. | ||
* '''FM-Sound board:''' installs YM2413 + logic; requires decoder ROM patch or EverDrive. | * '''FM-Sound board:''' installs YM2413 + logic; requires decoder ROM patch or EverDrive. | ||
== | == Trivia & Pop-culture == | ||
* European advertising used the slogan '''“The Leader of the 8-Bit Revolution”''' even after the Mega Drive launched. | * European advertising used the slogan '''“The Leader of the 8-Bit Revolution”''' even after the Mega Drive launched. | ||
* Brazilian TecToy versions included *Mônica no Castelo do Dragão* (a comic-book reskin of *Wonder Boy II*). | * Brazilian TecToy versions included *Mônica no Castelo do Dragão* (a comic-book reskin of *Wonder Boy II*). | ||
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'''See also / further reading''' | '''See also / further reading''' | ||
* [[Master System II Maintenance Guide]] | * [[Sega Master System II General Maintenance|Master System II Maintenance Guide]] | ||
* [[Master System II Troubleshooting Guide]] | * [[Sega Master System II Troubleshooting Guide|Master System II Troubleshooting Guide]] | ||
* [[Master System II Capacitor Replacement Guide]] | * [[Sega Master System II Capacitor Replacement Guide|Master System II Capacitor Replacement Guide]] | ||
* [[SMS II AV Output Guide]] | * [[SMS II AV Output Guide]] | ||
[[Category:Sega Systems]] | [[Category:Sega Systems]] | ||