If this (bank switching) is the problem, then why do the 3 ROMs work? Why do the 5 ROMs not work? All 8 ROMs work, or all not work, not? 3 ROMs why work in external function ROM card? Servant, Keydos, BASIC 8. If C128 mode reset routine find a internal, or external function ROM, then the system automatically set $FF00 register, and start ROM. Or not? I do not find C128 disassembled ROM list on internet.
At Servant ROM "." key = "CALL EXROM". If I switch external function ROM card to Keydos, then I start internal U36 Servant, this OK, if I press "." key, external Keydos start. This (Servant and keydos) works in the 1764/1750 REU socket (I saw it on internet, but I do not have 1764 REU). Do I have to modify the start (inic) program routines in the 5 ROM contents? How?
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: link
Hello. Where is it possible to buy new switches to C64, C128, Plus 4, 1541-II, 1581? I find suitable swithes nowhere. I want to substitute the original switches. I do not want to transform the machine to a some other kind of switch.
I was hoping, I find here min. 1 man who knows the function of the C128DCR. With +12V, but without U109 = machine start OK. With +12V, but without U112 = machine start OK. With +12V, but without U60 = machine start OK. With +12V, but without U57 = machine start not OK. This normal. www.zimmers.net/anonftp/pub/cbm/schematics/computers/c128/manual/83.gif I will find the reason.