Editing Atari 520ST (section)

== Technical Details ==
Comprehensive IC inventory (typical 520ST) – major functions and common part numbers:
{| class="wikitable"
! Function !! Common part(s) / package !! Notes
|-
| CPU || MC68000P8 (DIP‑64), MC68000FN8 (PLCC‑68) || 8.00 MHz core.<ref>{{cite web |url=https://www.alldatasheet.net/datasheet-pdf/pdf/135463/MOTOROLA/MC68000P8.html |title=MC68000P8 datasheet |publisher=Motorola |access-date=2025-08-13}}</ref>
|-
| Video “Shifter” || C025914‑38/‑38A; CO70713/I10356 || Reads DRAM and serializes pixels.<ref>{{cite web |url=https://forums.atariage.com/topic/247569-huge-list-of-new-original-atari-custom-ic-chips-transistors-etc/ |title=Atari custom IC list |publisher=AtariAge |access-date=2025-08-13}}</ref>
|-
| GLUE || C025915‑38A || Bus/timing decode, video timing assist.<ref>{{cite web |url=https://forums.atariage.com/topic/247569-huge-list-of-new-original-atari-custom-ic-chips-transistors-etc/ |title=Atari custom IC list |publisher=AtariAge |access-date=2025-08-13}}</ref>
|-
| MMU (DRAM) || C025912‑38; later C100109 || Row/col multiplex/refresh to DRAM.<ref>{{cite web |url=https://forums.atariage.com/topic/247569-huge-list-of-new-original-atari-custom-ic-chips-transistors-etc/ |title=Atari custom IC list |publisher=AtariAge |access-date=2025-08-13}}</ref>
|-
| DMA (ACSI/FDD) || C025913‑38 || 8‑bit ACSI and FDC DMA, IRQ/DRQ handshake.<ref>{{cite web |url=https://mikrosk.github.io/doitarchive/doit_st/0904.htm |title=DMA, ROM, and WD1772 photo |publisher=DOIT_ST |access-date=2025-08-13}}</ref>
|-
| Floppy controller || WD1772‑00‑02 / ‑02‑02 || 250 kbit/s DD; many ‑02‑02 parts OK at 16 MHz for HD mods.<ref>{{cite web |url=https://mikrosk.github.io/doitarchive/doit_st/0b03.htm |title=HD Disk ST |publisher=DOIT_ST |access-date=2025-08-13}}</ref>
|-
| MFP (timers/IRQs/U(S)ART) || MC68901 || 200 Hz system tick, vectorized interrupts.<ref>{{cite web |url=https://www.bighole.nl/pub/mirror/homepage.ntlworld.com/kryten_droid/Atari/ST/spg/st_prog_guide_1.htm |title=MFP details |publisher=Concise ST Prog Ref |access-date=2025-08-13}}</ref>
|-
| ACIAs (MIDI/IKBD) || 2× MC6850 || 7812.5 baud link to IKBD; 31.25 kbaud MIDI.<ref>{{cite web |url=https://www.muzines.co.uk/articles/atari-520st/9092 |title=Atari 520ST (MIDI hardware) |publisher=E&MM |date=1985-07 |access-date=2025-08-13}}</ref>
|-
| Sound/PIO || YM2149F || 3‑voice PSG + I/O (printer strobe/data, FDD selects, RTS/DTR).<ref>{{cite web |url=https://atarimuseum.ctrl-alt-rees.com/computers/16bits/STINTERN.htm |title=ST Internals – YM2149 regs |publisher=Ctrl‑Alt‑Rees |access-date=2025-08-13}}</ref>
|-
| RS‑232 transceivers || MC1488, MC1489 (or equivalents) || Level conversion for DB‑25 serial.<ref>{{cite web |url=https://www.manualslib.com/manual/2170364/Atari-520ste.html |title=STE Service Manual (I/O section) |publisher=ManualsLib |date=1991 |access-date=2025-08-13}}</ref>
|}
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