The DIY cartridge: JOLLY CARTRIDGE!
Posted: Sun Oct 17, 2021 6:11 am
Finally a basic DIY cartridge that can be any standard cartridge you want (and more):
the JOLLY CARTRIDGE is here!
Perfect for fiddling with all possible RAM expansion capabilities,
as a new cart for old downloaded software or as a support for your own new software even in small production batches.
The JOLLY CARTRIDGE supports up to two memory chips: U1 (ROM only) and U2 (ROM or RAM).
ROM chip(s):
64k EEPROM W27C512 (or equivalent) is recommended:
it doesn't need UV erasing, it's cheap, and it covers all possible JOLLYCART functions.
RAM chip:
32k SRAM HM62256 (or equivalent) is recommended:
it's cheap and it covers all possible JOLLYCART functions.
U1 (ROM) is mapped to I/O2 and 3, and can also be selected in BLK5.
All U1 areas can be switched between 2 banks ("L"/"H") via the J2 jumper.
U2 (ROM or RAM) is mapped to BLK2 and BLK3.
It can be selected in BLK1, and either in BLK5 or RAM1,2,3 (3k).
How to configure the JOLLY CARTRIDGE
J2:
Pin1 is not connected.
Pin2 is the A14 of U1 with a pull-up resistor (A14="H" if pin2 is not connected)
Pin3 is GND ("L").
J2 can select the desired “U1 bank” using a small 2.54mm switch, or a jumper, or a drop of solder or by leaving it not connected....
J1 is a bit more complicated.
Remember that the VIC20 decodes the memory areas enabling (in J1) the lines BLK5, 3KB, BLK1.
I/O2+3 are stably connected to U1,
BLK2+3 are stably connected to U2.
The on board memory "slices" that can be enabled by J1 are U1B5, U2B5, U2B1.
The rule is that a decoded line can only be connected to a single "memory slice" and that a "memory slice" can only be connected to a single decoded line.
The combinations of J1 and J2 cover almost all the mapping possibilities of U1 U2 chips inside a cartridge!
Some examples...
Two different 8K games in autostart BLK5:
A 16K(or more) game, any two (or more) BLKs combination,
for example into BLK 5 can be placed a launcher for the Scott Adams adventures. The previous configuration permit up to 32k of ROM, for example a multigame cart containing 9 games for unexpanded VIC20:
the chosen game will be copied to the VIC20 RAM and launched
Three games: 1x16k + 2x8k
Always (SJload or Rabbit) into I/O2,3 and
{32kram or [24kram + (Tools for BASIC or ML)]}
Ram expansion +3k or +32k (SJload on I/O2,3): A variant:
+32k expansion RAM: +24k RAM for BASIC +8k RAM into BLK5
+hidden into I/O areas: SJLOAD (7) for using your jiffydos modded disk drive (SYS40000)
+hidden into "no basic" RAM1,2,3 areas: EASYLOAD+ (7) for speed up your not jiffydos disk drive
A diagnostic cartridge PAL/NTSC
(for complete working it need also specific test harness):
This configuration is for new games that work only if loaded into RAM expansion....(two diode 1N4148 will be needed)
+24k ram expansion +13k ROM (BLK5+I/O2,3+RAM1,2,3).
At power up (or at reset) the firmware into BLK 5 will be auto started,
into the expanded ram the rom content will be copied and launched.
A 12.75k game can be performed (or a bigger game, if compressed...) The precedent configuration (+24kRAM, +13kROM) is like a "lite version" of a "DREAMCART" (+37kRAM, +64kROM): viewtopic.php?f=10&t=9950
Another information about JOLLY CARTRIDGE "naked board" version:
the PCB factory can't made the "45°fingers chamfered" because the PCB has a dimension too small,
then whoever chooses the "naked board" will have to smooth the two edges with a nail file or other tool.
The other versions (proto, games, ...) will be supplied with the edges already rounded.
the JOLLY CARTRIDGE is here!
Perfect for fiddling with all possible RAM expansion capabilities,
as a new cart for old downloaded software or as a support for your own new software even in small production batches.
The JOLLY CARTRIDGE supports up to two memory chips: U1 (ROM only) and U2 (ROM or RAM).
ROM chip(s):
64k EEPROM W27C512 (or equivalent) is recommended:
it doesn't need UV erasing, it's cheap, and it covers all possible JOLLYCART functions.
RAM chip:
32k SRAM HM62256 (or equivalent) is recommended:
it's cheap and it covers all possible JOLLYCART functions.
U1 (ROM) is mapped to I/O2 and 3, and can also be selected in BLK5.
All U1 areas can be switched between 2 banks ("L"/"H") via the J2 jumper.
U2 (ROM or RAM) is mapped to BLK2 and BLK3.
It can be selected in BLK1, and either in BLK5 or RAM1,2,3 (3k).
How to configure the JOLLY CARTRIDGE
J2:
Pin1 is not connected.
Pin2 is the A14 of U1 with a pull-up resistor (A14="H" if pin2 is not connected)
Pin3 is GND ("L").
J2 can select the desired “U1 bank” using a small 2.54mm switch, or a jumper, or a drop of solder or by leaving it not connected....
J1 is a bit more complicated.
Remember that the VIC20 decodes the memory areas enabling (in J1) the lines BLK5, 3KB, BLK1.
I/O2+3 are stably connected to U1,
BLK2+3 are stably connected to U2.
The on board memory "slices" that can be enabled by J1 are U1B5, U2B5, U2B1.
The rule is that a decoded line can only be connected to a single "memory slice" and that a "memory slice" can only be connected to a single decoded line.
The combinations of J1 and J2 cover almost all the mapping possibilities of U1 U2 chips inside a cartridge!
Some examples...
Two different 8K games in autostart BLK5:
A 16K(or more) game, any two (or more) BLKs combination,
for example into BLK 5 can be placed a launcher for the Scott Adams adventures. The previous configuration permit up to 32k of ROM, for example a multigame cart containing 9 games for unexpanded VIC20:
the chosen game will be copied to the VIC20 RAM and launched
Three games: 1x16k + 2x8k
Always (SJload or Rabbit) into I/O2,3 and
{32kram or [24kram + (Tools for BASIC or ML)]}
Ram expansion +3k or +32k (SJload on I/O2,3): A variant:
+32k expansion RAM: +24k RAM for BASIC +8k RAM into BLK5
+hidden into I/O areas: SJLOAD (7) for using your jiffydos modded disk drive (SYS40000)
+hidden into "no basic" RAM1,2,3 areas: EASYLOAD+ (7) for speed up your not jiffydos disk drive
A diagnostic cartridge PAL/NTSC
(for complete working it need also specific test harness):
This configuration is for new games that work only if loaded into RAM expansion....(two diode 1N4148 will be needed)
+24k ram expansion +13k ROM (BLK5+I/O2,3+RAM1,2,3).
At power up (or at reset) the firmware into BLK 5 will be auto started,
into the expanded ram the rom content will be copied and launched.
A 12.75k game can be performed (or a bigger game, if compressed...) The precedent configuration (+24kRAM, +13kROM) is like a "lite version" of a "DREAMCART" (+37kRAM, +64kROM): viewtopic.php?f=10&t=9950
Another information about JOLLY CARTRIDGE "naked board" version:
the PCB factory can't made the "45°fingers chamfered" because the PCB has a dimension too small,
then whoever chooses the "naked board" will have to smooth the two edges with a nail file or other tool.
The other versions (proto, games, ...) will be supplied with the edges already rounded.