UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

TonyDuell · 7th Oct 2019, 5:04 pm

The Dragon 32 was based on a Motorola example circuit for the 6883 SAM (Synchronous Address Multiplexer) chip. The Tandy/Radio Shack TRS-80 Color Computer ('CoCo') was based on the same circuit. The ROMs were different (meaning tokenised BASIC programs for one would not load on the other) and the other main difference was the printer port.

Anyway, I have several CoCos with disk drives. OS-9 (not the Apple thing, the one from Microware) was a wonderful operating system, allowing multitasking and even multiuser operation.

I also have a CoCo3, a machine which had no Dragon equivalent. The SAM and VDG (6847 video chip) were replaced by a Tandy custom IC called GIME (Graphics, Interupts, Memory Enhancements) which gave an 80*24 text display with true lower case,640*200 graphics and a memory management circuit allowing up to 512K of RAM.

I don't know if I mentioned this before, but I really understood how to use that CoCo 3 (and other machines of a similar vintage) to do the things I wanted. I built interfaces, wrote device drivers, wrote simple application programs to do things like program EPROMs, convert data files, control lamps and motors and the like.

I can't figure out how to do that sort of thing on a modern computer. Sure it's a lot more powerful, but it's doing the things the manufacturers want. It is actually doing less _for me_.

7th Oct 2019, 5:04 pm	#3
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,213	Re: Dragon 32 The Dragon 32 was based on a Motorola example circuit for the 6883 SAM (Synchronous Address Multiplexer) chip. The Tandy/Radio Shack TRS-80 Color Computer ('CoCo') was based on the same circuit. The ROMs were different (meaning tokenised BASIC programs for one would not load on the other) and the other main difference was the printer port. Anyway, I have several CoCos with disk drives. OS-9 (not the Apple thing, the one from Microware) was a wonderful operating system, allowing multitasking and even multiuser operation. I also have a CoCo3, a machine which had no Dragon equivalent. The SAM and VDG (6847 video chip) were replaced by a Tandy custom IC called GIME (Graphics, Interupts, Memory Enhancements) which gave an 8024 text display with true lower case,640200 graphics and a memory management circuit allowing up to 512K of RAM. I don't know if I mentioned this before, but I really understood how to use that CoCo 3 (and other machines of a similar vintage) to do the things I wanted. I built interfaces, wrote device drivers, wrote simple application programs to do things like program EPROMs, convert data files, control lamps and motors and the like. I can't figure out how to do that sort of thing on a modern computer. Sure it's a lot more powerful, but it's doing the things the manufacturers want. It is actually doing less _for me_.