Welcome back to part 6 of my fourth SepTandy Spectacular. In the last post we began our look at the Color Computer by looking at its early periferals and add ons. In this post, we're going to take a look at its various floppy drives and floppy controller carts.
Once again unlike its predecessor, the Coco didnt need to have a periferal expansion box in order to add floppy disk capability, however, since the coco was more or less a low cost video terminal adapted into a computer, they couldn't really give it expansion slots for adding floppy drive like say the Apple II. However, since the Coco did have a ROM cartridge slot, it was possible to design a floppy controller interface that could plug into it, and that's exactly what Tandy did
The first disk drive interface was the Color Disk Kit #0 (Catalog number 26-3022), introduced in 1981, for $599 dollars.
A listing for the original Color Disk Kit #0 in the 1982 Radio Shack catalog.
The kit consisted of was a reference manual, a double-density, full height 5.25 inch floppy disk drive, a drive cable cable, and of course, the Disk Drive Controller Cart itself.
A listing for the original Color Disk Kit #0 in the 1982 Radio Shack catalog.
The kit consisted of was a reference manual, a double-density, full height 5.25 inch floppy disk drive, a drive cable cable, and of course, the Disk Drive Controller Cart itself.
The main guts are really in the cartridge itself. unlike say Commodore drives that had their own processor on board, or the Apple II and IBM PC with Floppy controller cards, the COCO kinda works somewhere in between. The cart looks just like any other Coco cart just being a bit longer and having an edge connector on the end for hooking up drives.
Inside the cart is a Western Digital WD1793 Floppy Disk Controller chip, An 8K ROM chip containing the Disk Extended Color BASIC language (More on that later), and the rest being just basic 74lsxx logic chips.
The drive itself is almost identical to the TRS-80 Model I's floppy drive, with the most notable difference being this large switch on the front. Now, I can find out exactly what this switch is. I dont know if its an extra power switch or some kind of write protect switch, or a reset switch or what. But what I do know is that these early drives only came with the 26-3022, later versions droped this switch.
Powering up the Coco with the Color Computer Controller plugged in will drop you into Disk Extended Color BASIC, a version of Color BASIC built into the 8K ROM of the cart I mentioned earlier. It's Identical to regular Extended Color BASIC, but as the name implies, it contains extra commands built in for manipulating disks such as DIR,COPY, FORMAT, Etc. It also adds disk specific LOAD and SAVE commands to BASIC as opposed to the Cassette based CLOAD and CSAVE. To give you an example, I'll just type out the HELLO WORLD! program and tell it to save the program to disk by typing: SAVE "HELLO". Then I'll reset the computer and load it back by typing LOAD "HELLO" and if I wanted to run it automatically, I can type a , R at the end.
While Disk Extended Color BASIC was initially the only operating system at launch, It wasn't long before a proper Disk Opperating system came along in the form of OS-9, developed and released by Microware Systems Corporation in 1979, Initially for multiple 6809 based systems with the Coco version releasing in 1983.
OS-9 Is notable as it provided several impressive features, including multitasking, multiuser support, a hierarchical file system, could support upto 64K of RAM, had the ability to use multiple drive types, and a UNIX type operrinting enviorment. It was very popular with Coco users and was offered alongside the Coco for the rest of the computers life
But there was a problem with this setup though, If you wanded to run a cartridge based program, you would need to remove the controller cart every time. So to solve this problem, Radio Shack created the TRS-80 Multi-Pak Interface, released in 1983, and retailed for $180.
A listing for the TRS-80 Multi-Pak Interface in the 1984 Radio Shack catalog.
With this, you could expand you cartidge slot from 1 to 4 and switch between the slots with a small switch on the front. It was also possible to use it to attach multiple drives and switch between them.
The TRS-80 Multi-Pak Interface
In 1985, the 26-3022 was replaced by the FD-501 cart. The catridge was much shorter, had gold plated conatcts for better reliability, and droppedn the infamous analog data seperator circuit which caused inherent unreliability.
The TRS-80 Multi-Pak Interface
Also in 1985, they introduced the Color Disk #0 Slimeline drives which changed the color to white, and came with a single height floppy drive rather than a full height. There was also a blank plate up top covering a spot were you could add an optional second drive.
A listing for the Color Disk #0 Slimeline in the 1985 Radio Shack catalog.
In 1985, the 26-3022 was replaced by the FD-501 cart. The catridge was much shorter, had gold plated conatcts for better reliability, and droppedn the infamous analog data seperator circuit which caused inherent unreliability.
A listing for the FD-501 in the 1985 Radio Shack catalog.
Hard drives also started to become a possibility with the introduction of the Hard Disk Interface, released in 1986, for $129.95.
A listing for the Hard Disk Interface in the 1987 Radio Shack catalog.
Its looks very similar to the disk controler carts, but with this you could hook up a Winchester Drive to use with OS-9, and free up drives to use for loading software.
The Hard Disk Interface
The last disk controller was the FD-502 released in 1988, and sold for $179.95.
A listing for the FD-502 in the 1989 Radio Shack computer catalog.
The FD-502 is notable as it finally added double sided disk support, in fact, Its the only Tandy model ever to incorporate true double-sided drives, and its drive power connectors are like those of typical 3.5" floppy drives rather than those of normal 5.25" drives. But power connectors are also reportedly wired differently than typical 3.5" drive connectors. As noted elsewhere, either a patched Disk BASIC or an alternative operating system is required to gain access to the second side of disks. A cooling fan must be installed for safe operation if a second drive is added.
Even though these drives were availible, most Coco Users didn't use them at first since they were expensive, so must just stuck to programs on cartridge or cassette. But disk drives were still popular for those that needed the extra storage. However the Cocos add ons didnt stop there as printers and modems were also availible. This concludes Part 6 of the fourth Septandy Spectacular, join me next time as we take a closer look at the Color Computer's printers and modems.
Also on a Side note, this blog marks my 100th entry! aIf there is anyone out there reading this, Thank you So much for sticking with me throughout this!
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