On Wed, Dec 4, 2024 at 5:46 PM Mike Katz <[email protected]> wrote: > > The story I heard is that Motorola went to Tandy asking them to use their > 6809 chip. > > Tandy said, ok, you design a system for us with a cost of $xxx and we will > sell it. > > Motorola then designed the color computer using the 6883 SAM chip which > handled almost all of the glue logic for the system. This includes address > decoding, DRAM refresh, system clock, etc. > > The CoCo was made up of 3 main chips: > > 6809E CPU (The E used a 2 phase clock so they could alternate cycle main RAM > and video RAM) > 6883 Synchronous Address Mutiplexor (took care of all of the glue logic) > 6845 Graphics Controller Chip
Actually a 6847 which is a rather different device > > Add RAM and a few Misc. chips and discretes and you have a CoCo! True. The schematic in the datasheet I pointed to also shows the ROMs and a pair of 6821 PIAs as in the CoCo. > > Great machine but no one at Tandy realized the power of the 6809. Maybe the > CoCo III came close to exploiting all that the 6809 could do. Tandy did sell Microware OS-9, BASIC-09. Pascal and C for the CoCo. That was a rather nice mutliuser OS. I remember at the tme I was runing OS-9 (initially leval 1 on a 64K CoCo 2, then level 2 on a 512K CoCo 3) and had to use MS-DOS on a computer at a company I was doing some work for. The latter felt so primitve by comparison. -tony
