jejones3141

I should say to start that I'm not a gamer. Back in the day I thought it cool that the TI 99/4A had a 16-bit processor, but when I look at the architecture now, it looks like it would be a pain to work with. The 6809, OTOH, is heavily influenced by the PDP-11. Not nearly as orthogonal; they were constrained by wanting to make it as easy to move from the 6800 as possible--but it's the best 8-bit (with some 16-bit capabilities) CPU there was. Two stack pointer registers, which made it a joy for fans of FORTH. A reasonable set of addressing modes, allowing position-independent code and letting one avoid the kludge of self-modifying code. The CoCo suffered from Tandy's cutting every possible corner and putting every possible burden on the CPU to let them skimp on hardware, so no hardware sprites no hardware sound chip; instead, there was a 6-bit DAC bit-banger serial I/O analog mice, I believe using the same 6-bit DAC, leading to the ultimate kludge to let one keep using those mice on the higher-resolution screens of the CoCo 3: the "high-res mouse adapter", which made the CPU check how long it took a capacitor to charge. You very quickly learned to always shove the mouse back to (0,0) whenever it wasn't in use to minimize the added overhead. I bought a CoCo 3 because it was the least expensive way to get a computer with a multitasking operating system, a C compiler (K&R 1st edition minus bitfields), and a reasonable amount of RAM. BASIC09 was and is a joy to use compared with the primitive microcomputer BASIC interpreters of the day. Said interpreters are an obstacle rather than an aid to writing any nontrivial program. Yeah, they skimped on the cases, too; cheap plastic. The TI is definitely better looking sitting on the desk, though people have documented cleaning some of that age-related grunge off their CoCo's cases. The CoCo has a cartridge port, and there was even a "Multi-Pak interface" to let you plug in multiple game cartridges and switch between them... and also plug in other cartridges, like floppy disk controllers. I got a third-party floppy controller, the Sardis Tech which had 8K of cache, rather than Radio Shack's, and bought dual 720 K floppy drives to run with more space than RS's single-sided 35-track drives until I got a hard drive. There are still third-party sources of hardware and software. The Triad 512 K RAM expansion Cloud 9 sells is the way to go now; smaller and cooler running. There were several third-party hard drive controllers for IDE, then for SCSI. Nowadays one can take the SD route. The CoCo SDC cartridge can take an SD or SDHC which can hold multiple floppy drive and hard drive images. Also, there's DriveWire, which lets you run that bit-banger serial port to any computer with a Java runtime environment and provides an extensive set of capabilities. (A Raspberry Pi will suffice to run the DriveWire server, and I bet someone's already hidden one in a CoCo case.) Serious CoCo users replace Motorola's 6809 (more precisely, 68B09E, a 2 MHz capable 6809 driven by external clock) with a Hitachi 6309. The 6309 comes up looking like a plain, mild-mannered 6809, but set a mode bit and suddenly new registers and instructions are available (e.g. block moves and divides), and the instructions it shares with the 6809 run faster--except that it takes more time and space to save additional state for an IRQ. NitrOS9 started out as a rewrite of OS-9 to take advantage of the 6309's capabilities. About display: CoCo 3 can do composite out. There are various solutions people have come up with to adapt to VGA and even to HDMI. To be honest, unless historical authenticity and preservation is important to you, there's a lot to be said for Roger Taylor's "CoCo on a Chip" project. Here's a friend's initial experience with it.