Editing Atari STE Troubleshooting Guide (section)

== STE Custom Chipset Overview ==

The STE replaced the separate GLUE and MMU chips with a single combined IC, and introduced a new Shifter with DMA sound capabilities:

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table"
! IC !! Designation !! Package !! Function
|-
| GST MCU || U400 (C300720 / C300589) || 144-pin QFP (surface-mount) || Combined GLUE + MMU: bus decode, address generation, DRAM control, video DMA addressing, DMA sound address counter, enhanced joystick/paddle/lightpen ports, clock generation
|-
| GST Shifter || (various part numbers) || DIP-40 or QFP (varies by board revision) || Video pixel serialisation, RGB output, DMA stereo sound output (8-bit PCM at 6258/12517/25033/50066 Hz)
|-
| BLiTTER || Atari BLiTTER || PLCC-68 || Hardware block transfer for graphics acceleration
|-
| DMA Controller || C025913 || DIP-40 || ACSI/floppy DMA (same as ST range)
|-
| WD1772 || Floppy controller || DIP-28 || Same as ST range
|-
| YM2149F || PSG sound + PIO || DIP-40 || Legacy sound; also controls drive select, printer port, RS-232 handshake lines
|-
| LMC1992 || Sound mixer || SMD || Microwire-controlled stereo mixer for volume, bass, treble, balance adjustment
|-
| MC68901 || MFP || DIP-48 || Timers, interrupts, RS-232 UART
|-
| MC6850 (×2) || ACIAs || DIP-24 || Keyboard/MIDI serial interfaces
|}