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This is for Heliophobe (about to take a knife to old Cap'n Silver :-) ), and others who requested info about modifying cartridges.

I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs.

Mike

315-5208 conversion

Quote

> This is for Heliophobe (about to take a knife to old Cap'n Silver :-) ), and others who requested info about modifying cartridges.

> I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs.

> Mike

Cool! now we just have to find a EPROM writer, I heard one of these are
very expensive :(

Quote

> Cool! now we just have to find a EPROM writer, I heard one of these are
> very expensive :(

not at all, not if you build your own (or get a nice guy to build you one for the price of parts).

About $20US in components is what it takes to build an EPROMr2, plans available at www.zws.com (under 'products'). (you also need to buy a power supply and a parallel cable, but you may have one lying around anyway).

Mike G.'s page has lots of good information about it too. Mike G.'s got a talent for explaining these sorts of things in understandable english.

Of course, I'd still like to invest money in a universal programmer (there's a 40 pin not-entirely-universal programmer for around $250 that's said to be reliable), which does eproms and eeproms of all kinds,microcontrollers, programmable logic devices, good fun stuff, in a nice clean box. But I'll hold off on that for now.

Quote

> I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs.

Thank you! You see, I would have soldered the wires to the ends of the pins in my ignorance.
BTW, what is the reason for cutting the trace and wiring the extra connection? I think you may have mentioned it before but I have forgotten.

Quote

> This is for Heliophobe (about to take a knife to old Cap'n Silver :-) ), and others who requested info about modifying cartridges.

I think captain silver is doomed no matter what, since I'll probably start with a non-mapped cartridge so I can at least have a 32k (or 48k) workspace to play around with, before I do anything with my one and only mapped cartridge, Penguin Land (which uses the 4 meg. mapper w/sram support, er, you knew that i bet).

(well I have a phantasy star too, but there's no way I'm doing anything to -that-)

I've been trying to find a solution for replacing the old mapping chips with something we can make. After some thought I don't think microcontrollers are the way to go: I was mistaken about the speed of pics, they run one instruction per -4- clockcycles, so the fastest pics run only 5 million instructions per second max, and every branch takes two instruction cycles, so it wouldn't be responsive enough to respond to the address bus in time. Scenix makes some 50mhz pic-clones, but I don't think you can program them with the cheap kits, and they're getting sued to charred stumps by Microchip for making them too much like pics, so I don't want to depend on them.
MCU's would be handy as controllers for a devcart, handling the PC interface and whatnot.

component based logic could get a bit messy, especially because you have to be able to read and write paging registers.

A PLD (with enough pins and some i/o ports) would be perfect, but I don't know of any cheap kits for programming PLD's the way you can build programmers for eproms, pics and atmel MCU's, and I really don't have several hundred to spend on a programmer right now. I'm working on an ABEL description of a SMS mapping chip, though, and I'll test it out and try to find a PLD that can handle it and is available to hobbyists.

FPGA's seem like overkill, but they could be handy in a multi-platform devcart, since you can reprogram on the fly with different mappers for different systems.Ther are $100ish FPGA prototyping kits, but I'm not sure what else you need to get started in the way of special cables, etc.

Quote

> > I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs.

> Thank you! You see, I would have soldered the wires to the ends of the pins in my ignorance.

Ouch! :-) I hope it wasn't too patronising. I've tried to keep it as simple as possible.

Quote

> BTW, what is the reason for cutting the trace and wiring the extra connection? I think you may have mentioned it before but I have forgotten.

The 128k ROMs have A16 on pin 22, whereas the equivalent EPROM has Output Enable on this pin (actually pin 24, since it's a 32 pin package). So the A16 line to pin 22 is cut, while the extra connection is made between A16 and pin 2 (which is the A16 line on the EPROM).

With other ROM sizes (256k etc) none of this is necessary, since the pinouts of the EPROM are an exact match - it's just a straight swap.

[mapping chips]

Quote

> A PLD (with enough pins and some i/o ports) would be perfect, but I don't know of any cheap kits for programming PLD's the way you can build programmers for eproms, pics and atmel MCU's, and I really don't have several hundred to spend on a programmer right now. I'm working on an ABEL description of a SMS mapping chip, though, and I'll test it out and try to find a PLD that can handle it and is available to hobbyists.

I'd like to know about this too, particularly if there's a simple programmer design available. It seems that Codemasters carts and some GG pirate carts use such a thing, so evidently it can be done.

Mike

Author	Message
Mike G Joined: 21 Apr 2000 Posts: 598 Location: Newcastle upon Tyne, England	Cartridge modification document Posted: Mon Aug 07, 2000 10:05 pm
	This is for Heliophobe (about to take a knife to old Cap'n Silver :-) ), and others who requested info about modifying cartridges. I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs. Mike 315-5208 conversion

PrOfUnD Darkness Joined: 29 Jun 1999 Posts: 383 Location: Brazil	Hey, nice! Posted: Tue Aug 08, 2000 4:31 pm
	Quote > This is for Heliophobe (about to take a knife to old Cap'n Silver :-) ), and others who requested info about modifying cartridges. > I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs. > Mike Cool! now we just have to find a EPROM writer, I heard one of these are very expensive :(

Heliophobe Site Admin Joined: 25 Oct 1999 Posts: 2029 Location: Monterey, California	Re: Hey, nice! Posted: Tue Aug 08, 2000 5:03 pm
	Quote > Cool! now we just have to find a EPROM writer, I heard one of these are > very expensive :( not at all, not if you build your own (or get a nice guy to build you one for the price of parts). About $20US in components is what it takes to build an EPROMr2, plans available at www.zws.com (under 'products'). (you also need to buy a power supply and a parallel cable, but you may have one lying around anyway). Mike G.'s page has lots of good information about it too. Mike G.'s got a talent for explaining these sorts of things in understandable english. Of course, I'd still like to invest money in a universal programmer (there's a 40 pin not-entirely-universal programmer for around $250 that's said to be reliable), which does eproms and eeproms of all kinds,microcontrollers, programmable logic devices, good fun stuff, in a nice clean box. But I'll hold off on that for now.

Heliophobe Site Admin Joined: 25 Oct 1999 Posts: 2029 Location: Monterey, California	Posted: Tue Aug 08, 2000 5:23 pm
	Quote > I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs. Thank you! You see, I would have soldered the wires to the ends of the pins in my ignorance. BTW, what is the reason for cutting the trace and wiring the extra connection? I think you may have mentioned it before but I have forgotten. Quote > This is for Heliophobe (about to take a knife to old Cap'n Silver :-) ), and others who requested info about modifying cartridges. I think captain silver is doomed no matter what, since I'll probably start with a non-mapped cartridge so I can at least have a 32k (or 48k) workspace to play around with, before I do anything with my one and only mapped cartridge, Penguin Land (which uses the 4 meg. mapper w/sram support, er, you knew that i bet). (well I have a phantasy star too, but there's no way I'm doing anything to -that-) I've been trying to find a solution for replacing the old mapping chips with something we can make. After some thought I don't think microcontrollers are the way to go: I was mistaken about the speed of pics, they run one instruction per -4- clockcycles, so the fastest pics run only 5 million instructions per second max, and every branch takes two instruction cycles, so it wouldn't be responsive enough to respond to the address bus in time. Scenix makes some 50mhz pic-clones, but I don't think you can program them with the cheap kits, and they're getting sued to charred stumps by Microchip for making them too much like pics, so I don't want to depend on them. MCU's would be handy as controllers for a devcart, handling the PC interface and whatnot. component based logic could get a bit messy, especially because you have to be able to read and write paging registers. A PLD (with enough pins and some i/o ports) would be perfect, but I don't know of any cheap kits for programming PLD's the way you can build programmers for eproms, pics and atmel MCU's, and I really don't have several hundred to spend on a programmer right now. I'm working on an ABEL description of a SMS mapping chip, though, and I'll test it out and try to find a PLD that can handle it and is available to hobbyists. FPGA's seem like overkill, but they could be handy in a multi-platform devcart, since you can reprogram on the fly with different mappers for different systems.Ther are $100ish FPGA prototyping kits, but I'm not sure what else you need to get started in the way of special cables, etc.

Mike G Joined: 21 Apr 2000 Posts: 598 Location: Newcastle upon Tyne, England	Posted: Sun Aug 13, 2000 10:58 am
	Quote > > I've written a short article (linked below) describing how to convert a 1 Megabit cartridge, with 315-5208 mapper, to accept 128k EPROMs. > Thank you! You see, I would have soldered the wires to the ends of the pins in my ignorance. Ouch! :-) I hope it wasn't too patronising. I've tried to keep it as simple as possible. Quote > BTW, what is the reason for cutting the trace and wiring the extra connection? I think you may have mentioned it before but I have forgotten. The 128k ROMs have A16 on pin 22, whereas the equivalent EPROM has Output Enable on this pin (actually pin 24, since it's a 32 pin package). So the A16 line to pin 22 is cut, while the extra connection is made between A16 and pin 2 (which is the A16 line on the EPROM). With other ROM sizes (256k etc) none of this is necessary, since the pinouts of the EPROM are an exact match - it's just a straight swap. [mapping chips] Quote > A PLD (with enough pins and some i/o ports) would be perfect, but I don't know of any cheap kits for programming PLD's the way you can build programmers for eproms, pics and atmel MCU's, and I really don't have several hundred to spend on a programmer right now. I'm working on an ABEL description of a SMS mapping chip, though, and I'll test it out and try to find a PLD that can handle it and is available to hobbyists. I'd like to know about this too, particularly if there's a simple programmer design available. It seems that Codemasters carts and some GG pirate carts use such a thing, so evidently it can be done. Mike

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