Home Page Forums MAME MAME 8bit Apples - Apple I, II, /// and the 16 bit GS

Please join me all in a rousing chorus of "Oh when the bytes come marching in ..." Do not hate the vertical video, it allows me to show both the screen and the contraption that holds the chip



This is the MFA computer doing (almost) what it was designed for: Helping people find their way into computer land with very hands-on methods.

The machine was expanded with a second parallel output card to have enough outputs for the nine address lines of the 2513 chargen ROM. Going through all three bit row addresses for each six bit character address, I then read the incoming data and saved it to a file on the MFA, transferred it to the PC and converted it to the BIN format that is used by the equivalent character generator in the Apple 1 driver: each five bit word is expanded to an eight bit byte with the top three bits set to zero. You can see the bottom right LED flashing although there's no cable connected - I thought first that I had to toggle the Output Inhibit aka Chip Enable line for each row, but in the end it was enough to pull it to GND. Thank goodness there were no timings to be observed.

This archive contains the ITT2020's ROMs and character ROM, this one for my Apple ][ with its language card. There are comments in the Apple 2 driver that might be resolved by these dumps. This particular machine has a lowercase chargen mod, both ROMs are dumped.