> (Now embarrassed, even though I'm sure I seen this on someone's 805x core) > The Atmel's use a 4 ticks per cycle vs. the original 12 ticks per cycle. > The Atmel's will run at up to 33 Mhz (8.25) mips or 40 Mhz depending on > where you look and what you believe. Dallas semi also makes a single cycle > 805x compatible proc. (DS89C420) that will run at 50 Mhz (50 Mips max) as > well as the 4 tick parts. Some of the chips also contain a small amount > MOVX compatible ram. > > It could be that I saw this selectable "turbo/compatibility" mode on a > Phillips core. Although, I can't seem to find this anywhere now. Since > some of these processors are advertised as "drop in" replacements, it stands > to reason that one would need the ability to set the processor into full > compatibility mode. I did find that some cores have timers that will > operate using the normal 12 ticks/cycle but can be individually switch to 4 > tick turbo mode. I've looked at too many datasheets from too many > manufacturers now to remember where I ran into the register selectable turbo > mode. > > BTW, one of my first microcontroller projects was a Basic-52 SBC using an > Atmel 89C52 (flash prog. loaded up with Intel BASIC) w/12 Mhz crystal, > Max232, a surplus 74HCTLS373 latch, a surplus Sony 58257P-12 32K SRAM, and > 7805 reg. crammed on a RS 276-168B breadboard with lots of jumper wires. No > rhyme or reason for the parts selection other than that's what I could find > at the local surplus outlet. Works like a champ after I finally added a > reset circuit (these things are a little 'PIC'kier than a PIC). I also had > to add an electrolytic cap to stop spontaneous resets. I thought it was a > bad solder joint somewhere causing it to be sensitive to the touch, it > turned out (after hours of re-soldering and checking) that the 9V battery > clip was breaking contact a little. It takes only a few uSecs of power > glitching to reset the cpu. ;-) Live and learn. The whole thing draws > about 25 mAmps including green power LED. Now, all I need is something to > put it in. I thought this was a pretty neat project since this > "computer" has more raw power than the $600.00 Trash-80 model 1 that I > learned to program on. I probably had all of $15.00 in the project. Hi Michael, Thaks for the info. Yes it's the new Philips ones that have the 6/12 selectable clock divider thingy. I looked up the Atmel architectural overview data sheet and eventually found a reference to instructions taking 1, 2 or 4us at 12MHz. That means the good old divide by 12 scheme. I'm not saying "you're wrong ha ha!", just was kind of hoping they had made some new developments! I know what it's like looking over so many data sheets. I still spec 8051's over PIC in some projects. I always add a reset generator chip though, the PIC's are so much nicer this way. My favourite big 8051 chip might be the Philips 89C51RD+, 64K Flash, In Application Programmable etc, price about NZ$17 (US$7) for 1. Winbond also have some good ones with fast execution, good price. Dallas allways too dear, Cygnal ridiculously expensive. My first micro board I made was a Philips 80c552 (68pin PLCC) with a 8 or 32K RAM chip, 8/16/32K EPROM, 74HCT573 latch, 8 dip switches, 8 LEDs, 2 x PWM outputs, 8 x analog inputs, buzzer, 5V reg. I was lucky to do this at work and make this as a proper PCB. I used an EPROM emulator to get code into it. The only fault I had initially was I left out the earth track to the '573, very hard to fault find! I was over the moon when my first "flash the LED" program worked! The board still works and I have used it to test out many code/hardware ideas. Nice talking to you. Brent Brown Electronic Design Solutions 16 English Street Hamilton, New Zealand Ph/fax: +64 7 849 0069 Mobile/text: 025 334 069 eMail: brent.brown@clear.net.nz -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads