[simh] RSTS processor identification

Chris Zach cz at alembic.crystel.com
Fri Mar 5 20:15:22 CST 2021

>> Can't run split I/D space on any version of P/OS. Neither does it support supervisor mode. Also, the J11 on the Pro-380 is running a bit on the slow side. Rather sad, but I guess they didn't want to improve the support chips on the Pro, which limited speed, and they didn't want to start having Pro software that didn't run on all models, which prevented the I/D space and supervisor mode.

That sucks. I sometimes wonder how hard it would be to code the hard 
disk driver, if it doesn't do DMA it's probably simple as dirt to be 
honest. Any idea if it worked like MCSP or was it totally off the wall?

> The most embarassing blunder with the Pro is that the bus supports DMA, but no I/O cards use it.  Even though a bunch of them should have -- hard disk controller obviously, network adapter possibly as well.

I think they used an intel chipset to handle the CTI bus, so the normal 
Q-Bus DMA methods just doesn't work. Hm. Wonder if the problem is they 
just didn't build the driver to support DMA, or if they found some 
problem that made DMA just not work at all....

The 380 *was* a mess, mine is a formidable bit of kit with DECNA and 
everything, but without I/D space it's really not too very useful as 
more than a really nice VT terminal.

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