Re: VAXstation 3100/30 KA420 SCSI DMA problem on netboot (and fix)

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

kwellsch@ wrote:

> Oh, but wait. The document title made for another interesting search
> item "ka43 system board specification" which lead me to a document
> with this title:
> 
> "Engineering Specification for the KA43 Processor Module"
> 
> Looking at the discussion for the NCR chip an 80 series like the KA42,
> it has an interesting reference to a "compatibility mode" with a "reduced
> 16K" DMA buffer to match what the VS410 (aka microVax 2000) uses...

Hmm. This document claims that "STC_MODE Storage controller mode"
register is at 200C00E0 and it looks similar function as KA420.

However this description doesn't match results of read data from
200C00E0, and actually the document doesn't mention about 200C00B0.

Maybe we should check if SCSI DMA transfers work on netboot
(i.e. firmware sets proper DMA mode on netboot or not) on KA43 m76..

---
Izumi Tsutsui