Being needlessly pedantic as always ;-) they didn't reprogram the interface "chip" but simply redirected calls to the serial routines in the Kernal ROM to themselves. The Epyx FastLoad is a typical device; it sets various vectored Kernal routines to call a 256-byte block of code that sits in the designated I/O area at $df00 (mapped in through some expansion port signal magic from the 8K cartridge ROM itself). This code banks in the main ROM, which overlays the $8000-9fff range, containing the actual loader. As has been pointed out, since all Commodore disk drives are intelligent peripherals, most loaders modify the OS on both sides of the serial bus link and the FastLoad is no exception. It uploads a small asynchronous loader to the disk drive that instead of the one serial bit I believe uses the ATN line as a 2-bit parallel line (this was common practice in many loaders) with a complementary loader on the 64 side, starts the serial transfer, and then cleans up after itself, switches back to the 256-byte stub which banks the cartridge ROM back out, and exits back to the calling program. I particularly like the FastLoad since it works on PAL and NTSC machines since the loader timing is not too fussy (believe me, there are many loaders that are really picky about this), and it is insanely cheap and plentiful. I own seven of them, and I don't think I paid more than $5 for any one of them. The one I use in my 128DCR has a switch controlling one of the I/O lines (I forget which) so that I can disable it easily and go to 128 mode without having to unplug it. As I recall, it was not the tape that was the problem but early 64s that had some problem with the CIAs then in use. Rather than actually try to fix the problem, Commodore just crippled the serial bus protocol so it would still function (just much more slowly). Worse, the default serial bus protocol does not recover well from timing errors. Things like VIC-II DMA really gum the works up (this is why the Kernal turns the sprites off when you LOAD something, but it messes up *all* serial transfers -- try repeatedly reading the disk error channel with eight sprites showing on screen and it will randomly lock up [nothing a quick RUN-STOP/RESTORE can't cure though]). Certainly the C64 was capable of much more, but Commodore didn't get it right until the burst serial mode which came standard on the 128s, 1571s and 1581s, and was just breathtakingly fast (even by objective standards). Well, on the C=one, we may actually see real USB on the clock ports, but it still comes with a standard IEC serial bus port! :-) -- ----------------------------- personal page: http://www.armory.com/~spectre/ -- Cameron Kaiser, Point Loma Nazarene University * ckaiser(a)stockholm.ptloma.edu -- The only thing to fear is fearlessness -- R. E. M. -------------------------

--- Bryan Pope <bpope(a)wordstock.com> wrote: Nope... not the ones my company did c. 1983-1985... but we wrote kiddie software. I've never seen a copy of our stuff on the 'net. *sniff* I did a web search of some of our titles once and found my discussion of them on classiccmp and *one* other reference - in a resume from our head programmer. We were well regarded in our day (three of Reader's Digest's top 5 selling titles), but obviously, history paints a different picture. Not even good enough to steal. :-( We also supported the BBC Micro and the Apple II (with eventual support of the PC and PCjr, but those platforms weren't popular for the home yet). -ethan P.S. - for the curious, the titles were written by Software Productions; the three biggest names were "Alphabet Beasts and Company", "Micro Mother Goose" and "Micro Habitats". "Cross Swords" never made it out of development. __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com