Two bank eight image ROM cartridge
This cartridge is a development from three devices/cartridges I've made in the past. The first time I made a switchable ROM was way back in the early 1990's, then, about 5 years ago I made a switchable battery backed RAM cartridge giving 2 banks of 16 images each, the BBSRAMextreme. More recently I made a very slimmed down 32K cartridge that is small to suit my Electron Ultra and it is this I want to make some changes to.
The alterations will include increasing the ROM size to 128K, giving each bank four switchable images and adding a small piano style switch to make the selection as easy as possible. I kept the board size the same and added a space to note the image names readable from the front.
The board arrived and I've assembled it, only five parts, two resistors, one capacitor , a socket and a dip switch!
I programmed the 29F010 (PLCC32) using the TL866-II-Plus with eight images and inserted into the socket.
My choice of ROM images are:
Address: Image:
00000 ADI
04000 ADT
08000 AMXSP(1)
0C000 AMXSP(2)
10000 HIBASIC
14000 HI BASIC EDITOR
18000 ADVANCED BASIC EDITOR (1)
1C000 ADVANCED BASIC EDITOR (2)
My second choices are:
Address: Image:
00000 ACP
04000 AFM
08000 STARWORD
0C000 STARSPELL
10000 WORDWISE PLUS
14000 STARMON
18000 SHEET (part of Intersheet)
1C000 VIEWSHEET
And my third choices are:
Address: Image:
00000 STARSHIP COMMAND (1)
04000 STARSHIP COMMAND (2)
08000 HOPPER
0C000 EMPTY
10000 SNAPPER
14000 EMPTY
18000 EMPTY (These next two banks are empty so I can switch off the auto booting to the game)
1C000 EMPTY
All four catridge slots full including the MMFS catridge.
Switch Position:
ON/ON Address 00000 & 04000
ON/OFF Address 08000 & 0C000
OFF/ON Address 10000 & 14000
OFF/OFF Address 18000 & 1C000
ROM listing with switches in differing positions:
All in all I'm happy with this cartridge and I'll probably use it with my other Electrons.
Build details are in the zip file below, Circuit Diagram, Gerbers and Bill of Materials.
