Intellegent peripherals (was Re: MIT provides MULTICS source and documentation (DPS-8 simulation))

On Wed, Nov 14, 2007 at 11:29:59PM -0500, Roy J. Tellason wrote: The PET was even better for that... in the case of the C-64, you could load a small copier program into an unused buffer on each drive to do manage reading and writing each sector without the C-64 itself participating, but it meant that you couldn't then use the bus for something else, printing, say. Until the 2031, PET IEEE drives were dual-drive units, presumably to amortize the cost of the intellegent controller, the power supply, the case, over two spindles (a dual 5.25" ~170K-diskette drive was well over the cost of the computer it was attached to in 1979, in the range of $2200). The DOS for the 2040/3040/4040/8050/8250 drives had a "copy drive N to drive M" command (I'd quote chapter and verse, but I don't have access to the 'net right now). One of the CPUs on the drive (before the 1540, there were multiple 6502-family CPUs in the box) would read one drive, then write that buffer to the other drive without extra buffer copying and without putting the traffic on the bus. You could then, say, use your IEEE-488 acoustic coupler to logon to a BBS while disks were copying, or print to a printer, or whatever, since the IEEE bus was not involved in that disk-to-disk copy. Yes, the C-64 could do it, and yes, it was cheaper than the way the PET did it, but it wasn't the first nor was it the fastest. -ethan -- Ethan Dicks, A-333-S Current South Pole Weather at 15-Nov-2007 at 08:21 Z South Pole Station PSC 468 Box 400 Temp -41.3 F (-40.7 C) Windchill -65.9 F (-54.4 C) APO AP 96598 Wind 7.9 kts Grid 119 Barometer 681.6 mb (10568 ft) Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html