6502
e> An eight-bit ef="module.php?name=Lexikon&file=search&eid=1&query=microprocessor">microprocessor designed by {MOS Technologies} around 1975 and made by {Rockwell}. Unlike the ef="module.php?name=Lexikon&file=search&eid=1&query=Intel 8080">Intel 8080 and its kind, the 6502 had very few ef="module.php?name=Lexikon&file=search&eid=1&query=registers">registers. It was an 8-bit processor, with 16-bit {address bus}. Inside was one 8-bit data register ({accumulator}), two 8-bit ef="module.php?name=Lexikon&file=search&eid=1&query=index registers">index registers and an 8-bit ef="module.php?name=Lexikon&file=search&eid=1&query=stack pointer">stack pointer (stack was preset from address 256 to 511). It used these index and stack registers effectively, with more ef="module.php?name=Lexikon&file=search&eid=1&query=addressing modes">addressing modes, including a fast zero-page mode that accessed memory locations from address 0 to 255 with an 8-bit address (it didn' t have to fetch a second byte for the address). Back when the 6502 was introduced, ef="module.php?name=Lexikon&file=search&eid=1&query=RAM">RAM was actually faster than ef="module.php?name=Lexikon&file=search&eid=1&query=CPU">CPUs, so it made sense to optimize for RAM access rather than increase the number of registers on a chip. The 6502 was used in the ef="module.php?name=Lexikon&file=search&eid=1&query=BBC Microcomputer">BBC Microcomputer, ef="module.php?name=Lexikon&file=search&eid=1&query=Apple II">Apple II, ef="module.php?name=Lexikon&file=search&eid=1&query=Commodore">Commodore, ef="module.php?name=Lexikon&file=search&eid=1&query=Apple Computer">Apple Computer and ef="module.php?name=Lexikon&file=search&eid=1&query=Atari">Atari {personal computers}. {Steve Wozniak} described it as the first chip you could get for less than a hundred dollars (actually a quarter of the ef="module.php?name=Lexikon&file=search&eid=1&query=6800">6800 price). The 6502' s ef="module.php?name=Lexikon&file=search&eid=1&query=indirect jump">indirect jump instruction, JMP (xxxx), was ef="module.php?name=Lexikon&file=search&eid=1&query=broken">broken. If the address was hexadecimal xxFF, the processor would not access the address stored in xxFF and xxFF + 1, but rather xxFF and xx00. The ef="module.php?name=Lexikon&file=search&eid=1&query=6510">6510 did not fix this bug, nor was it fixed in any of the other ef="module.php?name=Lexikon&file=search&eid=1&query=NMOS">NMOS versions of the 6502 such as the ef="module.php?name=Lexikon&file=search&eid=1&query=8502">8502. Bill Mensch at ef="module.php?name=Lexikon&file=search&eid=1&query=Western Design Center">Western Design Center was probably the first to fix it, in the ef="module.php?name=Lexikon&file=search&eid=1&query=65C02">65C02. The 6502 also had undocumented instructions. The ef="module.php?name=Lexikon&file=search&eid=1&query=65816">65816 is an expanded version of the 6502. There is a 6502 ef="module.php?name=Lexikon&file=search&eid=1&query=assembler">assembler by Doug Jones es@cs.uiowa.edu> which supports ef="module.php?name=Lexikon&file=search&eid=1&query=macros">macros and conditional features and can be used for linkage editing of object files. It requires ef="module.php?name=Lexikon&file=search&eid=1&query=Pascal">Pascal. See also ef="module.php?name=Lexikon&file=search&eid=1&query=cross-assembler">cross-assembler, ef="module.php?name=Lexikon&file=search&eid=1&query=RTI">RTI, ef="module.php?name=Lexikon&file=search&eid=1&query=Small-C">Small-C. (2001-01-02) e="border-width:thin; border-color:#333333; border-style:dashed; padding:5px;" align="left">In addition suitable contents:
[ ef="module.php?name=Lexikon&op=content&tid=31">2 ] [ ef="module.php?name=Lexikon&op=content&tid=78">6510 ] [ ef="module.php?name=Lexikon&op=content&tid=79">65816 ] [ ef="module.php?name=Lexikon&op=content&tid=80">6800 ] [ ef="module.php?name=Lexikon&op=content&tid=109">8080 ] [ ef="module.php?name=Lexikon&op=content&tid=134">= ] [ ef="module.php?name=Lexikon&op=content&tid=135">@ ] [ ef="module.php?name=Lexikon&op=content&tid=210">accumulator ] [ ef="module.php?name=Lexikon&op=content&tid=262">ad ] [ ef="module.php?name=Lexikon&op=content&tid=303">address ] [ ef="module.php?name=Lexikon&op=content&tid=304">address bus ] [ ef="module.php?name=Lexikon&op=content&tid=307">addressing mode ] [ ef="module.php?name=Lexikon&op=content&tid=396">ag ] [ ef="module.php?name=Lexikon&op=content&tid=433">al ] [ ef="module.php?name=Lexikon&op=content&tid=543">AM ] [ ef="module.php?name=Lexikon&op=content&tid=544">am ] [ ef="module.php?name=Lexikon&op=content&tid=592">an ] [ ef="module.php?name=Lexikon&op=content&tid=689">Apple II ] [ ef="module.php?name=Lexikon&op=content&tid=740">ar ] [ ef="module.php?name=Lexikon&op=content&tid=743">arc ] [ ef="module.php?name=Lexikon&op=content&tid=800">as ] [ ef="module.php?name=Lexikon&op=content&tid=849">assembler ] [ ef="module.php?name=Lexikon&op=content&tid=894">at ] [ ef="module.php?name=Lexikon&op=content&tid=903">Atari ] [ ef="module.php?name=Lexikon&op=content&tid=996">av ] [ ef="module.php?name=Lexikon&op=content&tid=1025">B ] [ ef="module.php?name=Lexikon&op=content&tid=1026">b ] [ ef="module.php?name=Lexikon&op=content&tid=1034">ba ] [ ef="module.php?name=Lexikon&op=content&tid=1160">BBC ] [ ef="module.php?name=Lexikon&op=content&tid=1161">BBC Microcomputer ] [ ef="module.php?name=Lexikon&op=content&tid=1168">BC ] [ ef="module.php?name=Lexikon&op=content&tid=1181">be ] [ ef="module.php?name=Lexikon&op=content&tid=1269">bi ] [ ef="module.php?name=Lexikon&op=content&tid=1334">bit ] [ ef="module.php?name=Lexikon&op=content&tid=1368">bj ] [ ef="module.php?name=Lexikon&op=content&tid=1535">br ] [ ef="module.php?name=Lexikon&op=content&tid=1590">broken ] [ ef="module.php?name=Lexikon&op=content&tid=1672">bus ] [ ef="module.php?name=Lexikon&op=content&tid=1695">by ] [ ef="module.php?name=Lexikon&op=content&tid=1699">byte ] [ ef="module.php?name=Lexikon&op=content&tid=1708">C ] [ ef="module.php?name=Lexikon&op=content&tid=1724">ca ] [ ef="module.php?name=Lexikon&op=content&tid=1863">cat ] [ ef="module.php?name=Lexikon&op=content&tid=1896">cc ] [ ef="module.php?name=Lexikon&op=content&tid=2001">ch ] [ ef="module.php?name=Lexikon&op=content&tid=2069">chip ] [ ef="module.php?name=Lexikon&op=content&tid=2099">ci ] [ ef="module.php?name=Lexikon&op=content&tid=2136">ck ] [ ef="module.php?name=Lexikon&op=content&tid=2138">cl ] [ ef="module.php?name=Lexikon&op=content&tid=2247">co ] [ ef="module.php?name=Lexikon&op=content&tid=2330">com ] [ ef="module.php?name=Lexikon&op=content&tid=2490">Computer ] [ ef="module.php?name=Lexikon&op=content&tid=2491">computer ] [ ef="module.php?name=Lexikon&op=content&tid=2545">con ] [ ef="module.php?name=Lexikon&op=content&tid=2767">CP ] [ ef="module.php?name=Lexikon&op=content&tid=2786">CPU ] [ ef="module.php?name=Lexikon&op=content&tid=2791">cr ] [ ef="module.php?name=Lexikon&op=content&tid=2828">cross-assembler ] [ ef="module.php?name=Lexikon&op=content&tid=2900">cu ] [ ef="module.php?name=Lexikon&op=content&tid=2976">D ] [ ef="module.php?name=Lexikon&op=content&tid=3006">data ] [ ef="module.php?name=Lexikon&op=content&tid=3136">dd ] [ ef="module.php?name=Lexikon&op=content&tid=3151">de ] [ ef="module.php?name=Lexikon&op=content&tid=3177">dec ] [ ef="module.php?name=Lexikon&op=content&tid=3304">design ] [ ef="module.php?name=Lexikon&op=content&tid=3436">ding ] [ ef="module.php?name=Lexikon&op=content&tid=3565">do ] [ ef="module.php?name=Lexikon&op=content&tid=3568">doc ] [ ef="module.php?name=Lexikon&op=content&tid=3573">document ] [ ef="module.php?name=Lexikon&op=content&tid=3592">dollar ] [ ef="module.php?name=Lexikon&op=content&tid=3752">du ] [ ef="module.php?name=Lexikon&op=content&tid=3865">ec ] [ ef="module.php?name=Lexikon&op=content&tid=3896">ed ] [ ef="module.php?name=Lexikon&op=content&tid=3923">edu ] [ ef="module.php?name=Lexikon&op=content&tid=3929">ee ] [ ef="module.php?name=Lexikon&op=content&tid=3946">eg ] [ ef="module.php?name=Lexikon&op=content&tid=4148">er ] [ ef="module.php?name=Lexikon&op=content&tid=4171">es ] [ ef="module.php?name=Lexikon&op=content&tid=4199">et ] [ ef="module.php?name=Lexikon&op=content&tid=4404">fas ] [ ef="module.php?name=Lexikon&op=content&tid=4452">feature ] [ ef="module.php?name=Lexikon&op=content&tid=4485">FF ] [ ef="module.php?name=Lexikon&op=content&tid=4497">fi ] [ ef="module.php?name=Lexikon&op=content&tid=4520">file ] [ ef="module.php?name=Lexikon&op=content&tid=4595">fix ] [ ef="module.php?name=Lexikon&op=content&tid=4700">fo ] [ ef="module.php?name=Lexikon&op=content&tid=4727">for ] [ ef="module.php?name=Lexikon&op=content&tid=4828">fr ] [ ef="module.php?name=Lexikon&op=content&tid=5057">ge ] [ ef="module.php?name=Lexikon&op=content&tid=5134">gh ] [ ef="module.php?name=Lexikon&op=content&tid=5141">gi ] [ ef="module.php?name=Lexikon&op=content&tid=5205">gn ] [ ef="module.php?name=Lexikon&op=content&tid=5434">h ] [ ef="module.php?name=Lexikon&op=content&tid=5512">hardware ] [ ef="module.php?name=Lexikon&op=content&tid=5540">hat ] [ ef="module.php?name=Lexikon&op=content&tid=5611">hex ] [ ef="module.php?name=Lexikon&op=content&tid=5612">hexadecimal ] [ ef="module.php?name=Lexikon&op=content&tid=5681">hn ] [ ef="module.php?name=Lexikon&op=content&tid=5768">hr ] [ ef="module.php?name=Lexikon&op=content&tid=5779">ht ] [ ef="module.php?name=Lexikon&op=content&tid=5791">hu ] [ ef="module.php?name=Lexikon&op=content&tid=5931">id ] [ ef="module.php?name=Lexikon&op=content&tid=5956">ie ] [ ef="module.php?name=Lexikon&op=content&tid=6013">il ] [ ef="module.php?name=Lexikon&op=content&tid=6064">in ] [ ef="module.php?name=Lexikon&op=content&tid=6068">inc ] [ ef="module.php?name=Lexikon&op=content&tid=6082">index ] [ ef="module.php?name=Lexikon&op=content&tid=6194">int ] [ ef="module.php?name=Lexikon&op=content&tid=6230">Intel 8080 ] [ ef="module.php?name=Lexikon&op=content&tid=6413">io ] [ ef="module.php?name=Lexikon&op=content&tid=6449">ir ] [ ef="module.php?name=Lexikon&op=content&tid=6482">is ] [ ef="module.php?name=Lexikon&op=content&tid=6558">it ] [ ef="module.php?name=Lexikon&op=content&tid=6589">J ] [ ef="module.php?name=Lexikon&op=content&tid=6681">jo ] [ ef="module.php?name=Lexikon&op=content&tid=6748">jump ] [ ef="module.php?name=Lexikon&op=content&tid=6789">ke ] [ ef="module.php?name=Lexikon&op=content&tid=6792">ken ] [ ef="module.php?name=Lexikon&op=content&tid=6822">ki ] [ ef="module.php?name=Lexikon&op=content&tid=6904">kw ] [ ef="module.php?name=Lexikon&op=content&tid=6918">la ] [ ef="module.php?name=Lexikon&op=content&tid=7023">ld ] [ ef="module.php?name=Lexikon&op=content&tid=7081">less than ] [ ef="module.php?name=Lexikon&op=content&tid=7091">Lex ] [ ef="module.php?name=Lexikon&op=content&tid=7107">li ] [ ef="module.php?name=Lexikon&op=content&tid=7176">link ] [ ef="module.php?name=Lexikon&op=content&tid=7281">location ] [ ef="module.php?name=Lexikon&op=content&tid=7399">ls ] [ ef="module.php?name=Lexikon&op=content&tid=7415">lu ] [ ef="module.php?name=Lexikon&op=content&tid=7441">ly ] [ ef="module.php?name=Lexikon&op=content&tid=7457">M ] [ ef="module.php?name=Lexikon&op=content&tid=7463">ma ] [ ef="module.php?name=Lexikon&op=content&tid=7505">macro ] [ ef="module.php?name=Lexikon&op=content&tid=7579">mall ] [ ef="module.php?name=Lexikon&op=content&tid=7749">memory ] [ ef="module.php?name=Lexikon&op=content&tid=7753">memory location ] [ ef="module.php?name=Lexikon&op=content&tid=7848">micro ] [ ef="module.php?name=Lexikon&op=content&tid=7880">microprocessor ] [ ef="module.php?name=Lexikon&op=content&tid=8019">mm ] [ ef="module.php?name=Lexikon&op=content&tid=8032">mo ] [ ef="module.php?name=Lexikon&op=content&tid=8040">mod ] [ ef="module.php?name=Lexikon&op=content&tid=8046">mode ] [ ef="module.php?name=Lexikon&op=content&tid=8079">module ] [ ef="module.php?name=Lexikon&op=content&tid=8114">MOS ] [ ef="module.php?name=Lexikon&op=content&tid=8120">MOS Technologies ] [ ef="module.php?name=Lexikon&op=content&tid=8167">mp ] [ ef="module.php?name=Lexikon&op=content&tid=8258">mu ] [ ef="module.php?name=Lexikon&op=content&tid=8384">N ] [ ef="module.php?name=Lexikon&op=content&tid=8386">na ] [ ef="module.php?name=Lexikon&op=content&tid=8460">nc ] [ ef="module.php?name=Lexikon&op=content&tid=8472">ne ] [ ef="module.php?name=Lexikon&op=content&tid=8627">ng ] [ ef="module.php?name=Lexikon&op=content&tid=8630">ni ] [ ef="module.php?name=Lexikon&op=content&tid=8660">nl ] [ ef="module.php?name=Lexikon&op=content&tid=8675">no ] [ ef="module.php?name=Lexikon&op=content&tid=8760">ns ] [ ef="module.php?name=Lexikon&op=content&tid=8787">nu ] [ ef="module.php?name=Lexikon&op=content&tid=8820">O ] [ ef="module.php?name=Lexikon&op=content&tid=8838">object ] [ ef="module.php?name=Lexikon&op=content&tid=8964">om ] [ ef="module.php?name=Lexikon&op=content&tid=9014">op ] [ ef="module.php?name=Lexikon&op=content&tid=9096">optimize ] [ ef="module.php?name=Lexikon&op=content&tid=9132">OS ] [ ef="module.php?name=Lexikon&op=content&tid=9196">oz ] [ ef="module.php?name=Lexikon&op=content&tid=9204">pa ] [ ef="module.php?name=Lexikon&op=content&tid=9228">page ] [ ef="module.php?name=Lexikon&op=content&tid=9235">page mode ] [ ef="module.php?name=Lexikon&op=content&tid=9457">pe ] [ ef="module.php?name=Lexikon&op=content&tid=9519">personal computer ] [ ef="module.php?name=Lexikon&op=content&tid=9550">ph ] [ ef="module.php?name=Lexikon&op=content&tid=9651">pl ] [ ef="module.php?name=Lexikon&op=content&tid=9762">point ] [ ef="module.php?name=Lexikon&op=content&tid=9766">pointer ] [ ef="module.php?name=Lexikon&op=content&tid=9821">port ] [ ef="module.php?name=Lexikon&op=content&tid=9908">pr ] [ ef="module.php?name=Lexikon&op=content&tid=9995">process ] [ ef="module.php?name=Lexikon&op=content&tid=10001">processor ] [ ef="module.php?name=Lexikon&op=content&tid=10144">pt ] [ ef="module.php?name=Lexikon&op=content&tid=10244">quarter ] [ ef="module.php?name=Lexikon&op=content&tid=10253">query ] [ ef="module.php?name=Lexikon&op=content&tid=10305">RAM ] [ ef="module.php?name=Lexikon&op=content&tid=10364">rc ] [ ef="module.php?name=Lexikon&op=content&tid=10385">re ] [ ef="module.php?name=Lexikon&op=content&tid=10489">register ] [ ef="module.php?name=Lexikon&op=content&tid=10767">ro ] [ ef="module.php?name=Lexikon&op=content&tid=10873">RTI ] [ ef="module.php?name=Lexikon&op=content&tid=10887">ru ] [ ef="module.php?name=Lexikon&op=content&tid=10918">S ] [ ef="module.php?name=Lexikon&op=content&tid=11010">sc ] [ ef="module.php?name=Lexikon&op=content&tid=11150">se ] [ ef="module.php?name=Lexikon&op=content&tid=11281">set ] [ ef="module.php?name=Lexikon&op=content&tid=11376">si ] [ ef="module.php?name=Lexikon&op=content&tid=11389">sig ] [ ef="module.php?name=Lexikon&op=content&tid=11561">Small-C ] [ ef="module.php?name=Lexikon&op=content&tid=11651">so ] [ ef="module.php?name=Lexikon&op=content&tid=11934">st ] [ ef="module.php?name=Lexikon&op=content&tid=11939">stack ] [ ef="module.php?name=Lexikon&op=content&tid=11945">stack pointer ] [ ef="module.php?name=Lexikon&op=content&tid=12043">Steve Wozniak ] [ ef="module.php?name=Lexikon&op=content&tid=12068">store ] [ ef="module.php?name=Lexikon&op=content&tid=12109">struct ] [ ef="module.php?name=Lexikon&op=content&tid=12133">su ] [ ef="module.php?name=Lexikon&op=content&tid=12206">support ] [ ef="module.php?name=Lexikon&op=content&tid=12359">T ] [ ef="module.php?name=Lexikon&op=content&tid=12416">tar ] [ ef="module.php?name=Lexikon&op=content&tid=12440">tc ] [ ef="module.php?name=Lexikon&op=content&tid=12588">th ] [ ef="module.php?name=Lexikon&op=content&tid=12721">to ] [ ef="module.php?name=Lexikon&op=content&tid=12787">tr ] [ ef="module.php?name=Lexikon&op=content&tid=12939">tw ] [ ef="module.php?name=Lexikon&op=content&tid=12986">ua ] [ ef="module.php?name=Lexikon&op=content&tid=13008">ug ] [ ef="module.php?name=Lexikon&op=content&tid=13030">um ] [ ef="module.php?name=Lexikon&op=content&tid=13146">up ] [ ef="module.php?name=Lexikon&op=content&tid=13175">us ] [ ef="module.php?name=Lexikon&op=content&tid=13310">ve ] [ ef="module.php?name=Lexikon&op=content&tid=13335">version ] [ ef="module.php?name=Lexikon&op=content&tid=14075">yt ] [ ef="module.php?name=Lexikon&op=content&tid=14102">zero ]
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