PIO 2 Mode

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Zitat: yaqube

I have made my own replacements for PALs responsible for IDE interface. Now they feature PIO2 transfer mode timing. Any ATA-3 compliant device (manufactured after 1996) is capable of working in this mode since power-up. The maximum transfer rate is 8.3 MB/s. Actual values depend on your accelerator card.

All you have to do is to replace U901 and U902 with new GAL16V8 devices (my motherboard was equipped with reprogrammable PALCE devices so only reprogramming was required). Unfortunately to remove these parts from the motherboard hot air desoldering tool is required (don't forget to screen the daughter board slot to avoid thermal damage).

I also modified the scsi.device (last known version 44.2) back to use word transfers instead of long words as it's faster (setting A1 selects slower 8-bit access timing). The speed gain isn't impressive but it's worth the hassle (3.8 → 4.1 MB/s). See attached scanned picture for A4000 IDE interface details. Interestingly the initial design was going to implement PIO0-2 transfer modes.

Theorie

vorher/nachher

	A3630	A3640	MK-I	x	y
vorher
nachher

Probleme

Bisher noch nicht geklärt: nicht jede Version der GALs/PALs funktioniert auf jedem A4000-Desktop-Board.

Ansonsten bisher wohl keine Problem.

Files

A4000 für die GAL's U901 und U902: a4kidepio2.zip

A4000-T für die GALs … momentan im erweiterten Final-Test 10.02.2012

Links/Download

zu Nachweisquellen
zu Dokumentationen
- LA-Diagramme A4000T PIO-2 (223kB)
- Statemachine PIO2 (8kB)
Software

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