Hello.
I built a 8×32=256 KB internal function ROM (U36) EPROM.
Servant, Keydos, Superchip, Super 81 utilities, BASIC 8, TASS (turbo assembler), GEOS128 V2 1571, GEOS128 V2 1581.
All ROM OK with 3 switches. I use C128DCR.
I modified a C64 EPROM card to external function ROM.
I installed a other 256 KB EPROM into card with 8 ROMs, but 5 ROMs not work, not start (I remove internal U36 EPROM).
3 OK, Servant, Keydos, BASIC 8.
Why do the 5 ROMs not work?
Internal and external function ROM banks, page 10-11: http://www.cubic.org/~doj/c64/mapping128.pdf
C128 external function ROM problem
Re: C128 external function ROM problem
Got a schematic of what you did ?
Socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires. -John Steinbeck
Re: C128 external function ROM problem
Simple. I connect the expansion port ROMH and ROML to 74LS08 AND gate pin 12-13, I connect the output (pin 11) to 29020 flash ROM pin 24 OE, output enable (= 27256 EPROM pin 22). This = U36 internal function ROM.
C128 schematics: http://www.zimmers.net/anonftp/pub/cbm/ ... 4-left.gif
http://www.zimmers.net/anonftp/pub/cbm/ ... -right.gif
29C020: http://home.onego.ru/~sprut/Schemes/PRO ... 29c020.gif
74LS08: http://www.csus.edu/indiv/p/pangj/class ... g/7408.gif
I use C128 inbuilt monitorprogram, $B8000-$BCFFF, $BE000-$BFFFF OK, 32 KB $B8000-BFFFF external function ROM OK at all 8 ROMs. Bank 11.
At $D000-DFFF not bank command (always I/O, or RAM), but this 4 KB OK, because Servant and keydos all function OK.
Internal and external function ROM banks, page 10-11: http://www.cubic.org/~doj/c64/mapping128.pdf
Internal U36 ROM = bank 7.
C128 schematics: http://www.zimmers.net/anonftp/pub/cbm/ ... 4-left.gif
http://www.zimmers.net/anonftp/pub/cbm/ ... -right.gif
29C020: http://home.onego.ru/~sprut/Schemes/PRO ... 29c020.gif
74LS08: http://www.csus.edu/indiv/p/pangj/class ... g/7408.gif
I use C128 inbuilt monitorprogram, $B8000-$BCFFF, $BE000-$BFFFF OK, 32 KB $B8000-BFFFF external function ROM OK at all 8 ROMs. Bank 11.
At $D000-DFFF not bank command (always I/O, or RAM), but this 4 KB OK, because Servant and keydos all function OK.
Internal and external function ROM banks, page 10-11: http://www.cubic.org/~doj/c64/mapping128.pdf
Internal U36 ROM = bank 7.
Re: C128 external function ROM problem
I have to bow and admit this is beyond me.
AFAIK, ROML and ROMH can each signal an access to an area of 8KBytes at the most. Of you combine the 2 with a 74LS08 then this create an accessible area of 16K. Function ROMs for the C128 are supposed to be 32K.
AFAIK, ROML and ROMH can each signal an access to an area of 8KBytes at the most. Of you combine the 2 with a 74LS08 then this create an accessible area of 16K. Function ROMs for the C128 are supposed to be 32K.
Socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires. -John Steinbeck
Re: C128 external function ROM problem
Noooo. C128 expansion port pinouts.
C64, and C128 C64 mode.
C128 and C64 mode not same. In C64 mode ROML and ROMH = 8 KB, look Exrom+Game line.
In C128 mode Exrom and Game line unused.
Making a C64 Cartridge.
Making a C128 cartridge.
74LS08 OK, look C64 schematics: 250469 left side. 250469 right side.
251715 BASIC and KERNAL line connected into U3 74LS08 pin 12+13, and pin 11 connected into BASIC+KERNAL ROM pin 22.
Here 2×8 KB=16 KB. In C128 mode 2×16 KB=32 KB.
C64, and C128 C64 mode.
C128 and C64 mode not same. In C64 mode ROML and ROMH = 8 KB, look Exrom+Game line.
In C128 mode Exrom and Game line unused.
Making a C64 Cartridge.
Making a C128 cartridge.
74LS08 OK, look C64 schematics: 250469 left side. 250469 right side.
251715 BASIC and KERNAL line connected into U3 74LS08 pin 12+13, and pin 11 connected into BASIC+KERNAL ROM pin 22.
Here 2×8 KB=16 KB. In C128 mode 2×16 KB=32 KB.
Re: C128 external function ROM problem
If three programs work and five programs do not, then my best guess is that those five programs simply are not prepared to run from bank 8 (external function rom). Check their init codes with the monitor; maybe they switch to bank 4 because they expect to be run from there.
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