Common Boot up issues and errors

[vanwatson]

What are some common boot up issues and errors?

The watchdog circuits had what kind of problems or issues?

The ROM chip that had the Bios is has the boot up data also? or which ROM chip has the bios and boot up data?

[ed12]

in a comerical game >older<
there is no single bootrom chip presay..it is normaly shared..
now that beening said in some game's let's say packman
if e3 fail's board will not boot,but also this apply's to ram/video ram/sound ram
which is what the erpom's load the game into.

now the wdt watch dog timer
all it dose is monitor a few control line's,not nessarly reset,but rather _reset,
if that line goes sideway's for xx >mil sec's< the wdt kick's in and reset's the board
depending on the wdt layout it may also sample _ce and _cw and _clk
if them 4 line's are working right through it's sampler >nor gate as a rule<
then the timer count's out and is told by the cpu to reset it's self as all is ok,but if the mirco dose not flag it on time,the wdt will do a _reset,and reset your board..
as to your other thread about wdt and the batt,u have me at loss as i went through the schematic,and i can see a hard reset point..this is where i would start.

ed

[vanwatson]

So the Boot up data is on multiple Eprom chips?

How about the Bios? on multiple Eprom chips?

The CMos settings is on Eprom chips or NVram chip?

Why does an Arcade game need Cmos settings? the Cmos setting does what?

[ed12]

cmos is a type of memory
it is low current high cap. memory

nvram is a memory

both do the exact same thing
they fall under voltiale memory,which means remove the power and all cell's are
fff-ed out >blank<,give it a bat for back-up power and the memory stay's in it's
last state,so if someting time/date/game score was loaded with a bat it will retain that info as long as the battery voltaage is there

eprom's are erase-able read olny memory
which means the board in question can olny acess the info but not change it

rom is a read olny memory as a rule there is no way to erase it

ed

[vanwatson]

The NVRAM Daughter boards want to solder a wire from the NVRAM to a 74LS139 chip PIN#10.

Why Pin#10 on a 74LS139 would the NVRAM chip want that signal?

   

[ed12]

its a output line
so there must be data or a clk singal the nvram want's/need's ?

ed

[vanwatson]

The NVRAM daughter boards is for the Pac man logic board to get the High Score and Free Play