Hard reset on Atari 8-bit

[Hard reset on Atari 8-bit]

Name of Bulletin Board System please

It hasn't existed in many years but it was a small local BBS in McKinney TX called the McKinney Connection and it started out using a basic BBS software (can't remember what it was called, don't think it was FoReM). Then it was moved to BBS Express!

 

Later after I moved to a PC computer I ran a "Remote-Access" system that was on the Fido-Net global network called "The Avenger".

 

I haven't run a BBS since 1995.

 

This is from the FidoNet node list I just looked up online, from 1990:

 

1:124/4207 Wayne Thomason Allen TX The Avenger

[Hard reset on Atari 8-bit]

What resistance would be suitable for this reset to gnd method on a stock 800?

The resistor is only to prevent applying a hard ground to a hard voltage source. If you want to attempt this mod on an original 800, start with a 1k or 2k resistor and test to make sure it resets with that resistance. If it works, keep it, otherwise try a lower value (470 ohm for instance) until you find a value that works reliably.

 

I just was always cautious about doing a hard ground to reset because I didn't want to blow anything up. The RESET pin though, is a PULLED UP signal (denoted by a line over the RST). If I'm not mistaken, the mainboard is designed with a pull-up resistor to keep this pin high.

[Hard reset on Atari 8-bit]

Hard reset to coldstart is only relevant to the 400/800 since XL/XE uses it instead of the original NMI method - an improvement since a locked up CPU needed a full coldstart to recover on the older machines.

 

The equivalent method on the later machines is to toggle the state of the cartridge sense which will trigger a coldstart on reset due to the OS thinking a cartridge swap has occurred. The nickname "freezer" used as most of the OS variants will freeze the machine when the state change happens.

 

From what I've read, simply grounding the reset pin isn't always a good thing, hence the more complex circuits used in some cases.

That's weird. I started with a 400 in 1980 and as soon as I could afford one, I bought an 800XL and used it until retiring my Atari days in the late 90s. I could have sworn I did the reset pin thing on the 800XL but it must have been the 400 instead. I tested the pin-40 reset on my 130XE just down and it just acts like the reset button on the keyboard.

 

Both had a lot of modifications.

 

My 400 had a full-stroke keyboard and I built a 52k memory card from a kit and installed it. A fellow Atari person did a COMPOSITE VID/AUD mod on it.

My 800XL had a hand-built Newell 256K clone (built from schematic), a homebrewed 3-OS switch-board (similar to Newell's Ramrod XL but using an easier to find 3P2T/Center-off switch instead), an external 1200XL keyboard and a small postage-stamp size board that would lock the RAM in the 8K or 16K cartridge area when selected so copies of "booby-trapped" cartridges could be run properly.

 

I guess the reset button was on the 400....

 

My first floppy was a Percom that I upgraded with a DD data separator, an upgraded drive in the case and three DSQD slave drives connected via ribbon cable (I ran a bulletin board).

 

Too bad there's not an easy way to set the "reboot on reset" flag without poking the memory location.

[Hard reset on Atari 8-bit]

I've been reading several threads regarding various hard reset schemes people are using or have recommended and every method seems to be convoluted and complicated to deploy when back in the mid-80's many of my friends with Ataris and myself would simply run a momentary push-button switch through a resistor to pin-40 of the 6502 (Sally) chip that would pull the reset pin low while pressing the button.

 

This always seemed to me to be the most elegant solution and the simplest as well. Since pin-40 of the processor is the RESET pin, logically this would be the right path. Since the pin is pulled high through a resistor already, pulling it low (to ground) through a lower value resistor will cause the processor to reset, thus rebooting the computer.

 

The Atari users in my group of friends never had any failures due to this method of choice for hard resetting the Atari.

 

Does anyone know why other more intricate or complicated methods are the only ones talked about now (methods that use TTL chips and focus on various other chips and pins)??

[using the SDRIVE-MAX in conjunction with other drives]

As a matter of fact, all it would take for this mod would be a little bit of adhesive to attach the 74LS07 to the UNO in "dead-bug" fashion (pins sticking up), the resistors and wires attached to the respective pins and insulated, then the unnecessary pins of the chip either folded over or clipped off.