Eprom question..
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From: DMackey828 on 27 Jan 2010 04:55 Hey All, I'm trying to put 2 game files on ONE eprom. I can get the first program to start on the eprom. How does one go about putting a switch on the eprom to switch between the 2 games? I thought you could do it the same way you would setup a duel kernel rom but that didn't work. I know the eprom is good because the first games starts witch is actually on the upper side of the eprom. I also read back the file to disk from the eprom and it was exactly the same so thats good.. Any help would be great. I'm using a 27c256 32k eprom, the binary file is 32768 in size. Each game is 16k. TIA..
From: Vanessa Ezekowitz on 27 Jan 2010 12:13 On Wed, 27 Jan 2010 04:55:14 -0500 DMackey828 <n2dvm(a)NOSPAMarrl.net> wrote: > Hey All, > I'm trying to put 2 game files on ONE eprom. I can get the first > program to start on the eprom. How does one go about putting a switch > on the eprom to switch between the 2 games? > > I thought you could do it the same way you would setup a duel kernel > rom but that didn't work. I know the eprom is good because the first > games starts witch is actually on the upper side of the eprom. > > I also read back the file to disk from the eprom and it was exactly > the same so thats good.. > > Any help would be great. I'm using a 27c256 32k eprom, the > binary file is 32768 in size. Each game is 16k. One thing to make 100% sure of is whether the game images really have load addresses, and whether the final 32K image really needs one. Run the EPROM's address, data and control lines into the C64 as if it were actually a 16K EPROM, except the highest address line (A14?) doesn't connect anywhere in the C64 at all. Attach a switch there instead. There are two common ways to do it: Using a SPST switch: One of the pins goes to the high address line on the chip and also to one end of a 10K resistor. The other end of the resistor goes to +5v. The second pin on the switch goes to ground. The switch will ground the upper address line when closed ("on") to select the lower bank, and the resistor will pull the address line high when the switch is in the open position, selecting the upper bank. ....OR... Using a SPDT switch: Attach the center "common" pin to the chip's high address line. Wire one end of the switch to ground. Attach the other end of the switch to one end of a 1K resistor. Connect the free end of the resistor to +5v. The resistor's just there as a current limiter - you can leave it out if you want. ....OR... If you want to be fancy, a third way is to wire up a momentary pushbutton to a couple of capacitors and a 7474 flip-flop, with an LED to indicate when the high bank is selected. :-) -- "There are some things in life worth obsessing over. Most things aren't, and when you learn that, life improves." http://starbase.globalpc.net/~ezekowitz Vanessa E. <vanDEesLEsaTEezTHekISowitz(a)gmail.com> (Delete the obvious to email me) --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: DMackey828 on 27 Jan 2010 14:01 On Wed, 27 Jan 2010 11:13:01 -0600, Vanessa Ezekowitz <vanessaezekowitz(a)gmail.com> wrote: >On Wed, 27 Jan 2010 04:55:14 -0500 >DMackey828 <n2dvm(a)NOSPAMarrl.net> wrote: > >> Hey All, >> I'm trying to put 2 game files on ONE eprom. I can get the first >> program to start on the eprom. How does one go about putting a switch >> on the eprom to switch between the 2 games? >> >> I thought you could do it the same way you would setup a duel kernel >> rom but that didn't work. I know the eprom is good because the first >> games starts witch is actually on the upper side of the eprom. >> >> I also read back the file to disk from the eprom and it was exactly >> the same so thats good.. >> >> Any help would be great. I'm using a 27c256 32k eprom, the >> binary file is 32768 in size. Each game is 16k. > >One thing to make 100% sure of is whether the game images really have load >addresses, and whether the final 32K image really needs one. > >Run the EPROM's address, data and control lines into the C64 as if it were >actually a 16K EPROM, except the highest address line (A14?) doesn't connect >anywhere in the C64 at all. Attach a switch there instead. There are two >common ways to do it: > >Using a SPST switch: One of the pins goes to the high address line on the chip >and also to one end of a 10K resistor. The other end of the resistor goes to >+5v. The second pin on the switch goes to ground. The switch will ground >the upper address line when closed ("on") to select the lower bank, and the >resistor will pull the address line high when the switch is in the open >position, selecting the upper bank. > >...OR... > >Using a SPDT switch: Attach the center "common" pin to the chip's high address >line. Wire one end of the switch to ground. Attach the other end of the >switch to one end of a 1K resistor. Connect the free end of the resistor to >+5v. The resistor's just there as a current limiter - you can leave it out if >you want. > >...OR... > >If you want to be fancy, a third way is to wire up a momentary pushbutton to a >couple of capacitors and a 7474 flip-flop, with an LED to indicate when the >high bank is selected. :-) Hey Vanessa, I did manage to figure it out like 5 minutes after I posted my message. I did the same as if it were for a Jiffydos EPROM replacement. Got it working great. I'll be asking a lot of questions on the next one, putting 4 - 16k games on a 27512 - 64k eprom.. :) If anyone wants it, I can put the binary file on my FTP site so others can tinker with it if they want..
From: Clocky on 27 Jan 2010 17:50 "DMackey828" <n2dvm(a)NOSPAMarrl.net> wrote in message news:aj21m5hg6sqe8ena0caj59f456001rr845(a)4ax.com... > On Wed, 27 Jan 2010 11:13:01 -0600, Vanessa Ezekowitz > <vanessaezekowitz(a)gmail.com> wrote: > >>On Wed, 27 Jan 2010 04:55:14 -0500 >>DMackey828 <n2dvm(a)NOSPAMarrl.net> wrote: >> >>> Hey All, >>> I'm trying to put 2 game files on ONE eprom. I can get the first >>> program to start on the eprom. How does one go about putting a switch >>> on the eprom to switch between the 2 games? >>> >>> I thought you could do it the same way you would setup a duel kernel >>> rom but that didn't work. I know the eprom is good because the first >>> games starts witch is actually on the upper side of the eprom. >>> >>> I also read back the file to disk from the eprom and it was exactly >>> the same so thats good.. >>> >>> Any help would be great. I'm using a 27c256 32k eprom, the >>> binary file is 32768 in size. Each game is 16k. >> >>One thing to make 100% sure of is whether the game images really have load >>addresses, and whether the final 32K image really needs one. >> >>Run the EPROM's address, data and control lines into the C64 as if it were >>actually a 16K EPROM, except the highest address line (A14?) doesn't >>connect >>anywhere in the C64 at all. Attach a switch there instead. There are two >>common ways to do it: >> >>Using a SPST switch: One of the pins goes to the high address line on the >>chip >>and also to one end of a 10K resistor. The other end of the resistor goes >>to >>+5v. The second pin on the switch goes to ground. The switch will ground >>the upper address line when closed ("on") to select the lower bank, and >>the >>resistor will pull the address line high when the switch is in the open >>position, selecting the upper bank. >> >>...OR... >> >>Using a SPDT switch: Attach the center "common" pin to the chip's high >>address >>line. Wire one end of the switch to ground. Attach the other end of the >>switch to one end of a 1K resistor. Connect the free end of the resistor >>to >>+5v. The resistor's just there as a current limiter - you can leave it out >>if >>you want. >> >>...OR... >> >>If you want to be fancy, a third way is to wire up a momentary pushbutton >>to a >>couple of capacitors and a 7474 flip-flop, with an LED to indicate when >>the >>high bank is selected. :-) > > > Hey Vanessa, > I did manage to figure it out like 5 minutes after I posted my > message. I did the same as if it were for a Jiffydos EPROM > replacement. Got it working great. > > I'll be asking a lot of questions on the next one, putting 4 - 16k > games on a 27512 - 64k eprom.. :) > The method is the same, just add additional pull-up resistors and switches (like on the JiffyDOS ROM) on the extra address lines on the 27512 and then use the switches to choose which bank (ie game) to select.
From: DMackey828 on 28 Jan 2010 02:45
On Thu, 28 Jan 2010 06:50:40 +0800, "Clocky" <notgonn(a)happen.com> wrote: Snip... > >The method is the same, just add additional pull-up resistors and switches >(like on the JiffyDOS ROM) on the extra address lines on the 27512 and then >use the switches to choose which bank (ie game) to select. > Another country heard from.. Hey Clocky, how's things your way ? Ahh Got ya, I'll have to give that a try just for the hell of it. I will.. |