doug@edge.UUCP (Doug Pardee) (07/25/87)
If anyone wants to program his C-64 MIDI interface, here are the basics... A 6840 Programmable Timer Module is mapped at $DE00-$DE07. It is driven off of the CPU clock (1.02 MHz for US/Canada NTSC C-64s). On those MIDI interfaces with Tape-Sync output, it is driven by the 6840's "Timer 1". A 6850 Asynchronous Communications Interface Adapter is mapped at $DE08- $DE09. It is driven by a 500 KHz clock. Both devices are connected to the C-64's interrupt line. The 6840 and 6850 are made by Motorola, Hitachi, Fairchild, I think Signetics, and maybe other companies. Data sheets are widely available. I'll be glad to supply more details via E-mail. -- Doug Pardee, Edge Computer Corp; ihnp4!mot!edge!doug, seismo!ism780c!edge!doug
csz@well.UUCP (Carter Scholz) (07/27/87)
In article <882@edge.UUCP> doug@edge.UUCP (Doug Pardee) writes: >If anyone wants to program his C-64 MIDI interface, here are the basics... > >A 6840 Programmable Timer Module is mapped at $DE00-$DE07. It is driven >off of the CPU clock (1.02 MHz for US/Canada NTSC C-64s). On those MIDI >interfaces with Tape-Sync output, it is driven by the 6840's "Timer 1". > >A 6850 Asynchronous Communications Interface Adapter is mapped at $DE08- >$DE09. It is driven by a 500 KHz clock. > >Both devices are connected to the C-64's interrupt line. This information is not correct for the Sequential Circuits 242 interface (also known as the "Model T" from Dr. T's Software). The ACIA in these units is at $DE00-$DE03. Software written for the Passport interface (described above) will not run on the SCI. For further details on the SCI interface, contact Dr T's at 220 Boylston St, Suite 306, Chestnut Hill MA 02167, (617) 244-6954. They will send you a complete SCI-242 spec sheet with programming examples for $3. Recommended.